jvmti.h. To use these definitions add the J2SETM include directory to your include path and add
#include <jvmti.h>
to your source code. Deploying Agents An agent is deployed in a platform specific manner but is typically the platform equivalent of a dynamic library. On the WindowsTM operating system, for example, an agent library is a "Dynamic Linked Library" (DLL). On LinuxTM Operating Environment, an agent library is a shared object (.so file). An agent may be started at VM startup by specifying the agent library name using a command line option. Some implementations may support a mechanism to start agents in the live phase. The details of how this is initiated are implementation specific. Statically Linked Agents (since version 1.2.3) A native JVMTI Agent may be statically linked with the VM. The manner in which the library and VM image are combined is implementation-dependent. An agent L whose image has been combined with the VM is defined as statically linked if and only if the agent exports a function called Agent_OnLoad_L. If a statically linked agent L exports a function called Agent_OnLoad_L and a function called Agent_OnLoad, the Agent_OnLoad function will be ignored. If an agent L is statically linked, an Agent_OnLoad_L function will be invoked with the same arguments and expected return value as specified for the Agent_OnLoad function. An agent L that is statically linked will prohibit an agent of the same name from being loaded dynamically. The VM will invoke the Agent_OnUnload_L function of the agent, if such a function is exported, at the same point during VM execution as it would have called the dynamic entry point Agent_OnUnLoad. A statically loaded agent cannot be unloaded. The Agent_OnUnload_L function will still be called to do any other agent shutdown related tasks. If a statically linked agent L exports a function called Agent_OnUnLoad_L and a function called Agent_OnUnLoad, the Agent_OnUnLoad function will be ignored. If an agent L is statically linked, an Agent_OnAttach_L function will be invoked with the same arguments and expected return value as specified for the Agent_OnAttach function. If a statically linked agent L exports a function called Agent_OnAttach_L and a function called Agent_OnAttach, the Agent_OnAttach function will be ignored. Agent Command Line Options The term "command-line option" is used below to mean options supplied in the JavaVMInitArgs argument to the JNI_CreateJavaVM function of the JNI Invocation API. One of the two following command-line options is used on VM startup to properly load and run agents. These arguments identify the library containing the agent as well as an options string to be passed in at startup.
-agentlib:<agent-lib-name>=<options>
-agentlib: is the name of the library to load. Lookup of the library, both its full name and location, proceeds in a platform-specific manner. Typically, the <agent-lib-name> is expanded to an operating system specific file name. The <options> will be passed to the agent on start-up. For example, if the option -agentlib:foo=opt1,opt2 is specified, the VM will attempt to load the shared library foo.dll from the system PATH under WindowsTM or libfoo.so from the LD_LIBRARY_PATH under LinuxTM . If the agent library is statically linked into the executable then no actual loading takes place.
-agentpath:<path-to-agent>=<options>
-agentpath: is the absolute path from which to load the library. No library name expansion will occur. The <options> will be passed to the agent on start-up. For example, if the option -agentpath:c:\myLibs\foo.dll=opt1,opt2 is specified, the VM will attempt to load the shared library c:\myLibs\foo.dll. If the agent library is statically linked into the executable then no actual loading takes place.
Agent_OnLoad in the library will be invoked. If the agent library is statically linked into the executable then the system will attempt to invoke the Agent_OnLoad_<agent-lib-name> entry point where <agent-lib-name> is the basename of the agent. In the above example -agentpath:c:\myLibs\foo.dll=opt1,opt2, the system will attempt to find and call the Agent_OnLoad_foo start-up routine. Libraries loaded with -agentlib: or -agentpath: will be searched for JNI native method implementations to facilitate the use of Java programming language code in tools, as is needed for bytecode instrumentation. The agent libraries will be searched after all other libraries have been searched (agents wishing to override or intercept the native method implementations of non-agent methods can use the NativeMethodBind event). These switches do the above and nothing more - they do not change the state of the VM or JVM TI. No command line options are needed to enable JVM TI or aspects of JVM TI, this is handled programmatically by the use of capabilities. Agent Start-Up The VM starts each agent by invoking a start-up function. If the agent is started in the OnLoad phase the function Agent_OnLoad or Agent_OnLoad_L for statically linked agents will be invoked. If the agent is started in the live phase the function Agent_OnAttach or Agent_OnAttach_L for statically linked agents will be invoked. Exactly one call to a start-up function is made per agent. Agent Start-Up (OnLoad phase) If an agent is started during the OnLoad phase then its agent library must export a start-up function with the following prototype:
Or for a statically linked agent named 'L':JNIEXPORT jint JNICALL Agent_OnLoad(JavaVM *vm, char *options, void *reserved)
The VM will start the agent by calling this function. It will be called early enough in VM initialization that:JNIEXPORT jint JNICALL Agent_OnLoad_L(JavaVM *vm, char *options, void *reserved)
Agent_OnLoad or Agent_OnLoad_<agent-lib-name> function with <options> as the second argument - that is, using the command-line option examples, "opt1,opt2" will be passed to the char *options argument of Agent_OnLoad. The options argument is encoded as a modified UTF-8 string. If =<options> is not specified, a zero length string is passed to options. The lifespan of the options string is the Agent_OnLoad or Agent_OnLoad_<agent-lib-name> call. If needed beyond this time the string or parts of the string must be copied. The period between when Agent_OnLoad is called and when it returns is called the OnLoad phase. Since the VM is not initialized during the OnLoad phase, the set of allowed operations inside Agent_OnLoad is restricted (see the function descriptions for the functionality available at this time). The agent can safely process the options and set event callbacks with SetEventCallbacks. Once the VM initialization event is received (that is, the VMInit callback is invoked), the agent can complete its initialization.
Rationale: Early startup is required so that agents can set the desired capabilities, many of which must be set before the VM is initialized. In JVMDI, the -Xdebug command-line option provided very coarse-grain control of capabilities. JVMPI implementations use various tricks to provide a single "JVMPI on" switch. No reasonable command-line option could provide the fine-grain of control required to balance needed capabilities vs performance impact. Early startup is also needed so that agents can control the execution environment - modifying the file system and system properties to install their functionality.
The return value fromAgent_OnLoad or Agent_OnLoad_<agent-lib-name> is used to indicate an error. Any value other than zero indicates an error and causes termination of the VM. Agent Start-Up (Live phase) A VM may support a mechanism that allows agents to be started in the VM during the live phase. The details of how this is supported, are implementation specific. For example, a tool may use some platform specific mechanism, or implementation specific API, to attach to the running VM, and request it start a given agent. If an agent is started during the live phase then its agent library must export a start-up function with the following prototype:
Or for a statically linked agent named 'L':JNIEXPORT jint JNICALL Agent_OnAttach(JavaVM* vm, char *options, void *reserved)
The VM will start the agent by calling this function. It will be called in the context of a thread that is attached to the VM. The first argument <vm> is the Java VM. The <options> argument is the startup options provided to the agent. <options> is encoded as a modified UTF-8 string. If startup options were not provided, a zero length string is passed toJNIEXPORT jint JNICALL Agent_OnAttach_L(JavaVM* vm, char *options, void *reserved)
options. The lifespan of the options string is the Agent_OnAttach or Agent_OnAttach_<agent-lib-name> call. If needed beyond this time the string or parts of the string must be copied. Note that some capabilities may not be available in the live phase. The Agent_OnAttach or Agent_OnAttach_<agent-lib-name > function initializes the agent and returns a value to the VM to indicate if an error occurred. Any value other than zero indicates an error. An error does not cause the VM to terminate. Instead the VM ignores the error, or takes some implementation specific action -- for example it might print an error to standard error, or record the error in a system log. Agent Shutdown The library may optionally export a shutdown function with the following prototype:
Or for a statically linked agent named 'L':JNIEXPORT void JNICALL Agent_OnUnload(JavaVM *vm)
This function will be called by the VM when the library is about to be unloaded. The library will be unloaded (unless it is statically linked into the executable) and this function will be called if some platform specific mechanism causes the unload (an unload mechanism is not specified in this document) or the library is (in effect) unloaded by the termination of the VM. VM termination includes normal termination and VM failure, including start-up failure, but not, of course, uncontrolled shutdown. An implementation may also choose to not call this function if theJNIEXPORT void JNICALL Agent_OnUnload_L(JavaVM *vm)
Agent_OnAttach/ Agent_OnAttach_L function reported an error (returned a non-zero value). Note the distinction between this function and the VM Death event: for the VM Death event to be sent, the VM must have run at least to the point of initialization and a valid JVM TI environment must exist which has set a callback for VMDeath and enabled the event. None of these are required for Agent_OnUnload or Agent_OnUnload_<agent-lib-name> and this function is also called if the library is unloaded for other reasons. In the case that a VM Death event is sent, it will be sent before this function is called (assuming this function is called due to VM termination). This function can be used to clean-up resources allocated by the agent. JAVA_TOOL_OPTIONS Since the command-line cannot always be accessed or modified, for example in embedded VMs or simply VMs launched deep within scripts, a JAVA_TOOL_OPTIONS variable is provided so that agents may be launched in these cases. Platforms which support environment variables or other named strings, may support the JAVA_TOOL_OPTIONS variable. This variable will be broken into options at white-space boundaries. White-space characters include space, tab, carriage-return, new-line, vertical-tab, and form-feed. Sequences of white-space characters are considered equivalent to a single white-space character. No white-space is included in the options unless quoted. Quoting is as follows:
JNI_CreateJavaVM (in the JNI Invocation API) will prepend these options to the options supplied in its JavaVMInitArgs argument. Platforms may disable this feature in cases where security is a concern; for example, the Reference Implementation disables this feature on Unix systems when the effective user or group ID differs from the real ID. This feature is intended to support the initialization of tools -- specifically including the launching of native or Java programming language agents. Multiple tools may wish to use this feature, so the variable should not be overwritten, instead, options should be appended to the variable. Note that since the variable is processed at the time of the JNI Invocation API create VM call, options processed by a launcher (e.g., VM selection options) will not be handled. Environments The JVM TI specification supports the use of multiple simultaneous JVM TI agents. Each agent has its own JVM TI environment. That is, the JVM TI state is separate for each agent - changes to one environment do not affect the others. The state of a JVM TI environment includes:
GetEnv from Agent_OnLoad. Bytecode Instrumentation This interface does not include some events that one might expect in an interface with profiling support. Some examples include full speed method enter and exit events. The interface instead provides support for bytecode instrumentation, the ability to alter the Java virtual machine bytecode instructions which comprise the target program. Typically, these alterations are to add "events" to the code of a method - for example, to add, at the beginning of a method, a call to MyProfiler.methodEntered(). Since the changes are purely additive, they do not modify application state or behavior. Because the inserted agent code is standard bytecodes, the VM can run at full speed, optimizing not only the target program but also the instrumentation. If the instrumentation does not involve switching from bytecode execution, no expensive state transitions are needed. The result is high performance events. This approach also provides complete control to the agent: instrumentation can be restricted to "interesting" portions of the code (e.g., the end user's code) and can be conditional. Instrumentation can run entirely in Java programming language code or can call into the native agent. Instrumentation can simply maintain counters or can statistically sample events. Instrumentation can be inserted in one of three ways:
*.class files which have been modified to add the instrumentation. This method is extremely awkward and, in general, an agent cannot know the origin of the class files which will be loaded.ClassFileLoadHook event, triggered by the class load, provides this functionality. This mechanism provides efficient and complete access to one-time instrumentation.ClassFileLoadHook event, triggered by calling the RetransformClasses function. Classes can be modified multiple times and can be returned to their original state. The mechanism allows instrumentation which changes during the course of execution.ClassFileLoadHook event and the RetransformClasses function) and, during development, for fix-and-continue debugging (the RedefineClasses function). Care must be taken to avoid perturbing dependencies, especially when instrumenting core classes. For example, an approach to getting notification of every object allocation is to instrument the constructor on Object. Assuming that the constructor is initially empty, the constructor could be changed to:
public Object() {
MyProfiler.allocationTracker(this);
}
However, if this change was made using the ClassFileLoadHook event then this might impact a typical VM as follows: the first created object will call the constructor causing a class load of MyProfiler; which will then cause object creation, and since MyProfiler isn't loaded yet, infinite recursion; resulting in a stack overflow. A refinement of this would be to delay invoking the tracking method until a safe time. For example, trackAllocations could be set in the handler for the VMInit event.
static boolean trackAllocations = false;
public Object() {
if (trackAllocations) {
MyProfiler.allocationTracker(this);
}
}
The SetNativeMethodPrefix allows native methods to be instrumented by the use of wrapper methods. Bytecode Instrumentation of code in modules Agents can use the functions AddModuleReads, AddModuleExports, AddModuleOpens, AddModuleUses and AddModuleProvides to update a module to expand the set of modules that it reads, the set of packages that it exports or opens to other modules, or the services that it uses and provides. As an aid to agents that deploy supporting classes on the search path of the bootstrap class loader, or the search path of the class loader that loads the main class, the Java virtual machine arranges for the module of classes transformed by the ClassFileLoadHook event to read the unnamed module of both class loaders. Modified UTF-8 String Encoding JVM TI uses modified UTF-8 to encode character strings. This is the same encoding used by JNI. Modified UTF-8 differs from standard UTF-8 in the representation of supplementary characters and of the null character. See the Modified UTF-8 Strings section of the JNI specification for details. Specification Context Since this interface provides access to the state of applications running in the Java virtual machine; terminology refers to the Java platform and not the native platform (unless stated otherwise). For example:
jvmtiEnv*. An environment has information about its JVM TI connection. The first value in the environment is a pointer to the function table. The function table is an array of pointers to JVM TI functions. Every function pointer is at a predefined offset inside the array. When used from the C language: double indirection is used to access the functions; the environment pointer provides context and is the first parameter of each function call; for example:
jvmtiEnv *jvmti;
...
jvmtiError err = (*jvmti)->GetLoadedClasses(jvmti, &class_count, &classes);
When used from the C++ language: functions are accessed as member functions of jvmtiEnv; the environment pointer is not passed to the function call; for example:
jvmtiEnv *jvmti;
...
jvmtiError err = jvmti->GetLoadedClasses(&class_count, &classes);
Unless otherwise stated, all examples and declarations in this specification use the C language. A JVM TI environment can be obtained through the JNI Invocation API GetEnv function:
jvmtiEnv *jvmti;
...
(*jvm)->GetEnv(jvm, &jvmti, JVMTI_VERSION_1_0);
Each call to GetEnv creates a new JVM TI connection and thus a new JVM TI environment. The version argument of GetEnv must be a JVM TI version. The returned environment may have a different version than the requested version but the returned environment must be compatible. GetEnv will return JNI_EVERSION if a compatible version is not available, if JVM TI is not supported or JVM TI is not supported in the current VM configuration. Other interfaces may be added for creating JVM TI environments in specific contexts. Each environment has its own state (for example, desired events, event handling functions, and capabilities). An environment is released with DisposeEnvironment. Thus, unlike JNI which has one environment per thread, JVM TI environments work across threads and are created dynamically. Function Return Values JVM TI functions always return an error code via the jvmtiError function return value. Some functions can return additional values through pointers provided by the calling function. In some cases, JVM TI functions allocate memory that your program must explicitly deallocate. This is indicated in the individual JVM TI function descriptions. Empty lists, arrays, sequences, etc are returned as NULL. In the event that the JVM TI function encounters an error (any return value other than JVMTI_ERROR_NONE) the values of memory referenced by argument pointers is undefined, but no memory will have been allocated and no global references will have been allocated. If the error occurs because of invalid input, no action will have occurred. Managing JNI Object References JVM TI functions identify objects with JNI references (jobject and jclass) and their derivatives (jthread and jthreadGroup). References passed to JVM TI functions can be either global or local, but they must be strong references. All references returned by JVM TI functions are local references--these local references are created during the JVM TI call. Local references are a resource that must be managed (see the JNI Documentation). When threads return from native code all local references are freed. Note that some threads, including typical agent threads, will never return from native code. A thread is ensured the ability to create sixteen local references without the need for any explicit management. For threads executing a limited number of JVM TI calls before returning from native code (for example, threads processing events), it may be determined that no explicit management is needed. However, long running agent threads will need explicit local reference management--usually with the JNI functions PushLocalFrame and PopLocalFrame. Conversely, to preserve references beyond the return from native code, they must be converted to global references. These rules do not apply to jmethodID and jfieldID as they are not jobjects. Prerequisite State for Calling Functions Unless the function explicitly states that the agent must bring a thread or the VM to a particular state (for example, suspended), the JVM TI implementation is responsible for bringing the VM to a safe and consistent state for performing the function. Exceptions and Functions JVM TI functions never throw exceptions; error conditions are communicated via the function return value. Any existing exception state is preserved across a call to a JVM TI function. See the Java Exceptions section of the JNI specification for information on handling exceptions. Function Index
jvmtiError
Allocate(jvmtiEnv* env,
jlong size,
unsigned char** mem_ptr)
Allocate an area of memory through the JVM TI allocator. The allocated memory should be freed with Deallocate.
may be called during any phase
46
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionsize jlong The number of bytes to allocate.
Rationale: jlong is used for compatibility with JVMDI.
mem_ptr unsigned char** On return, a pointer to the beginning of the allocated memory. If size is zero, NULL is returned. Agent passes a pointer to a unsigned char*. On return, the unsigned char* points to a newly allocated array of size size. The array should be freed with Deallocate. Deallocate
jvmtiError
Deallocate(jvmtiEnv* env,
unsigned char* mem)
Deallocate mem using the JVM TI allocator. This function should be used to deallocate any memory allocated and returned by a JVM TI function (including memory allocated with Allocate). All allocated memory must be deallocated or the memory cannot be reclaimed.
may be called during any phase
47
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmem unsigned char * A pointer to the beginning of the allocated memory. Please ignore "On return, the elements are set." Agent passes an array of unsigned char. The incoming values of the elements of the array are ignored. On return, the elements are set. If mem is NULL, the call is ignored. Thread Thread functions:
jvmtiThreadInfo - Thread information structurejvmtiMonitorStackDepthInfo - Monitor stack depth information structurejthread specified to these functions can be a JNI reference to a platform thread or virtual thread. Some functions are not supported on virtual threads and return JVMTI_ERROR_UNSUPPORTED_OPERATION when called with a reference to a virtual thread. Get Thread State
jvmtiError
GetThreadState(jvmtiEnv* env,
jthread thread,
jint* thread_state_ptr)
Get the state of a thread. The state of the thread is represented by the answers to the hierarchical set of questions below:
JVMTI_THREAD_STATE_TERMINATED)JVMTI_THREAD_STATE_ALIVE)
JVMTI_THREAD_STATE_SUSPENDED)JVMTI_THREAD_STATE_INTERRUPTED)JVMTI_THREAD_STATE_IN_NATIVE)JVMTI_THREAD_STATE_RUNNABLE)JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER)JVMTI_THREAD_STATE_WAITING)
JVMTI_THREAD_STATE_WAITING_INDEFINITELYJVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT)JVMTI_THREAD_STATE_IN_OBJECT_WAIT)JVMTI_THREAD_STATE_PARKED)JVMTI_THREAD_STATE_SLEEPING)Thread State Flags Constant Value DescriptionThe following definitions are used to convert JVM TI thread state toJVMTI_THREAD_STATE_ALIVE0x0001 Thread is alive. Zero if thread is new (not started) or terminated.JVMTI_THREAD_STATE_TERMINATED0x0002 Thread has completed execution.JVMTI_THREAD_STATE_RUNNABLE0x0004 Thread is runnable.JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER0x0400 Thread is waiting to enter a synchronized block/method or, after anObject.wait(), waiting to re-enter a synchronized block/method.JVMTI_THREAD_STATE_WAITING0x0080 Thread is waiting.JVMTI_THREAD_STATE_WAITING_INDEFINITELY0x0010 Thread is waiting without a timeout. For example,Object.wait().JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT0x0020 Thread is waiting with a maximum time to wait specified. For example,Object.wait(long).JVMTI_THREAD_STATE_SLEEPING0x0040 Thread is sleeping --Thread.sleep.JVMTI_THREAD_STATE_IN_OBJECT_WAIT0x0100 Thread is waiting on an object monitor --Object.wait.JVMTI_THREAD_STATE_PARKED0x0200 Thread is parked, for example:LockSupport.park,LockSupport.parkUtilandLockSupport.parkNanos. A virtual thread that is sleeping, inThread.sleep, may have this state flag set instead ofJVMTI_THREAD_STATE_SLEEPING.JVMTI_THREAD_STATE_SUSPENDED0x100000 Thread suspended.java.lang.Thread.suspend()or a JVM TI suspend function (such asSuspendThread) has been called on the thread. If this bit is set, the other bits refer to the thread state before suspension.JVMTI_THREAD_STATE_INTERRUPTED0x200000 Thread has been interrupted.JVMTI_THREAD_STATE_IN_NATIVE0x400000 Thread is in native code--that is, a native method is running which has not called back into the VM or Java programming language code. This flag is not set when running VM compiled Java programming language code nor is it set when running VM code or VM support code. Native VM interface functions, such as JNI and JVM TI functions, may be implemented as VM code.JVMTI_THREAD_STATE_VENDOR_10x10000000 Defined by VM vendor.JVMTI_THREAD_STATE_VENDOR_20x20000000 Defined by VM vendor.JVMTI_THREAD_STATE_VENDOR_30x40000000 Defined by VM vendor.
java.lang.Thread.State style states.
java.lang.Thread.State Conversion Masks Constant Value DescriptionRules There can be no more than one answer to a question, although there can be no answer (because the answer is unknown, does not apply, or none of the answers is correct). An answer is set only when the enclosing answers match. That is, no more than one ofJVMTI_JAVA_LANG_THREAD_STATE_MASKJVMTI_THREAD_STATE_TERMINATED | JVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_RUNNABLE | JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER | JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELY | JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT Mask the state with this before comparisonJVMTI_JAVA_LANG_THREAD_STATE_NEW0java.lang.Thread.State.NEWJVMTI_JAVA_LANG_THREAD_STATE_TERMINATEDJVMTI_THREAD_STATE_TERMINATEDjava.lang.Thread.State.TERMINATEDJVMTI_JAVA_LANG_THREAD_STATE_RUNNABLEJVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_RUNNABLEjava.lang.Thread.State.RUNNABLEJVMTI_JAVA_LANG_THREAD_STATE_BLOCKEDJVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTERjava.lang.Thread.State.BLOCKEDJVMTI_JAVA_LANG_THREAD_STATE_WAITINGJVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_INDEFINITELYjava.lang.Thread.State.WAITINGJVMTI_JAVA_LANG_THREAD_STATE_TIMED_WAITINGJVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_WAITING | JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUTjava.lang.Thread.State.TIMED_WAITING
JVMTI_THREAD_STATE_RUNNABLEJVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTERJVMTI_THREAD_STATE_WAITINGJVMTI_THREAD_STATE_ALIVE is set). And if any of these are set, the enclosing answer JVMTI_THREAD_STATE_ALIVE is set. No more than one of
JVMTI_THREAD_STATE_WAITING_INDEFINITELYJVMTI_THREAD_STATE_WAITING_WITH_TIMEOUTJVMTI_THREAD_STATE_WAITING is set). And if either is set, the enclosing answers JVMTI_THREAD_STATE_ALIVE and JVMTI_THREAD_STATE_WAITING are set. No more than one of
JVMTI_THREAD_STATE_IN_OBJECT_WAITJVMTI_THREAD_STATE_PARKEDJVMTI_THREAD_STATE_SLEEPINGJVMTI_THREAD_STATE_ALIVE and JVMTI_THREAD_STATE_WAITING are set. Also, if JVMTI_THREAD_STATE_SLEEPING is set, then JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT is set. If a state A is implemented using the mechanism of state B then it is state A which is returned by this function. For example, if Thread.sleep(long) is implemented using Object.wait(long) then it is still JVMTI_THREAD_STATE_SLEEPING which is returned. More than one of
JVMTI_THREAD_STATE_SUSPENDEDJVMTI_THREAD_STATE_INTERRUPTEDJVMTI_THREAD_STATE_IN_NATIVEJVMTI_THREAD_STATE_ALIVE is set. And finally, JVMTI_THREAD_STATE_TERMINATED cannot be set unless JVMTI_THREAD_STATE_ALIVE is not set. The thread state representation is designed for extension in future versions of the specification; thread state values should be used accordingly, that is they should not be used as ordinals. Most queries can be made by testing a single bit, if use in a switch statement is desired, the state bits should be masked with the interesting bits. All bits not defined above are reserved for future use. A VM, compliant to the current specification, must set reserved bits to zero. An agent should ignore reserved bits -- they should not be assumed to be zero and thus should not be included in comparisons. Examples Note that the values below exclude reserved and vendor bits. The state of a thread blocked at a synchronized-statement would be:
JVMTI_THREAD_STATE_ALIVE + JVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTER
The state of a thread which hasn't started yet would be:
0
The state of a thread at a Object.wait(3000) would be:
JVMTI_THREAD_STATE_ALIVE + JVMTI_THREAD_STATE_WAITING +
JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT +
JVMTI_THREAD_STATE_MONITOR_WAITING
The state of a thread suspended while runnable would be:
JVMTI_THREAD_STATE_ALIVE + JVMTI_THREAD_STATE_RUNNABLE + JVMTI_THREAD_STATE_SUSPENDED
Testing the State In most cases, the thread state can be determined by testing the one bit corresponding to that question. For example, the code to test if a thread is sleeping:
jint state;
jvmtiError err;
err = (*jvmti)->GetThreadState(jvmti, thread, &state);
if (err == JVMTI_ERROR_NONE) {
if (state & JVMTI_THREAD_STATE_SLEEPING) { ...
For waiting (that is, in Object.wait, parked, or sleeping) it would be:
if (state & JVMTI_THREAD_STATE_WAITING) { ...
For some states, more than one bit will need to be tested as is the case when testing if a thread has not yet been started:
if ((state & (JVMTI_THREAD_STATE_ALIVE | JVMTI_THREAD_STATE_TERMINATED)) == 0) { ...
To distinguish timed from untimed Object.wait:
if (state & JVMTI_THREAD_STATE_IN_OBJECT_WAIT) {
if (state & JVMTI_THREAD_STATE_WAITING_WITH_TIMEOUT) {
printf("in Object.wait(long timeout)\n");
} else {
printf("in Object.wait()\n");
}
}
Relationship to java.lang.Thread.State The thread state represented by java.lang.Thread.State returned from java.lang.Thread.getState() is a subset of the information returned from this function. The corresponding java.lang.Thread.State can be determined by using the provided conversion masks. For example, this returns the name of the java.lang.Thread.State thread state:
err = (*jvmti)->GetThreadState(jvmti, thread, &state);
abortOnError(err);
switch (state & JVMTI_JAVA_LANG_THREAD_STATE_MASK) {
case JVMTI_JAVA_LANG_THREAD_STATE_NEW:
return "NEW";
case JVMTI_JAVA_LANG_THREAD_STATE_TERMINATED:
return "TERMINATED";
case JVMTI_JAVA_LANG_THREAD_STATE_RUNNABLE:
return "RUNNABLE";
case JVMTI_JAVA_LANG_THREAD_STATE_BLOCKED:
return "BLOCKED";
case JVMTI_JAVA_LANG_THREAD_STATE_WAITING:
return "WAITING";
case JVMTI_JAVA_LANG_THREAD_STATE_TIMED_WAITING:
return "TIMED_WAITING";
}
may only be called during the live phase
No
17
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread The thread to query. If thread is NULL, the current thread is used. thread_state_ptr jint* On return, points to state flags, as defined by the Thread State Flags. Agent passes a pointer to a jint. On return, the jint has been set. Get Current Thread
jvmtiError
GetCurrentThread(jvmtiEnv* env,
jthread* thread_ptr)
Get the current thread. The current thread is the Java programming language thread which has called the function. The function may return NULL in the start phase if the can_generate_early_vmstart capability is enabled and the java.lang.Thread class has not been initialized yet. Note that most JVM TI functions that take a thread as an argument will accept NULL to mean the current thread.
may only be called during the start or the live phase
No
18
1.1
Capabilities
Required Functionality
Parameters Name Type Descriptionthread_ptr jthread* On return, points to the current thread, or NULL. Agent passes a pointer to a jthread. On return, the jthread has been set. The object returned by thread_ptr is a JNI local reference and must be managed. Get All Threads
jvmtiError
GetAllThreads(jvmtiEnv* env,
jint* threads_count_ptr,
jthread** threads_ptr)
Get all live platform threads that are attached to the VM. The list of threads includes agent threads. It does not include virtual threads. A thread is live if java.lang.Thread.isAlive() would return true, that is, the thread has been started and has not yet terminated. The universe of threads is determined by the context of the JVM TI environment, which typically is all threads attached to the VM.
may only be called during the live phase
No
4
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthreads_count_ptr jint* On return, points to the number of threads. Agent passes a pointer to a jint. On return, the jint has been set. threads_ptr jthread** On return, points to an array of references, one for each thread. Agent passes a pointer to a jthread*. On return, the jthread* points to a newly allocated array of size *threads_count_ptr. The array should be freed with Deallocate. The objects returned by threads_ptr are JNI local references and must be managed. Suspend Thread
jvmtiError
SuspendThread(jvmtiEnv* env,
jthread thread)
Suspend the specified thread. If the calling thread is specified, this function will not return until some other thread calls ResumeThread. If the thread is currently suspended, this function does nothing and returns an error.
may only be called during the live phase
No
5
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads Parameters Name Type Description thread jthread The thread to suspend. If thread is NULL, the current thread is used. Suspend Thread List
jvmtiError
SuspendThreadList(jvmtiEnv* env,
jint request_count,
const jthread* request_list,
jvmtiError* results)
Suspend the request_count threads specified in the request_list array. Threads may be resumed with ResumeThreadList or ResumeThread. If the calling thread is specified in the request_list array, this function will not return until some other thread resumes it. Errors encountered in the suspension of a thread are returned in the results array, not in the return value of this function. Threads that are currently suspended do not change state.
may only be called during the live phase
No
92
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads Parameters Name Type Description request_count jint The number of threads to suspend. request_list const jthread* The list of threads to suspend. Agent passes in an array of request_count elements of jthread. results jvmtiError* An agent supplied array of request_count elements. On return, filled with the error code for the suspend of the corresponding thread. The error code will be JVMTI_ERROR_NONE if the thread was suspended by this call. Possible error codes are those specified for SuspendThread. Agent passes an array large enough to hold request_count elements of jvmtiError. The incoming values of the elements of the array are ignored. On return, the elements are set. Suspend All Virtual Threads
jvmtiError
SuspendAllVirtualThreads(jvmtiEnv* env,
jint except_count,
const jthread* except_list)
SuspendAllVirtualThreads is a preview API of the Java platform. Preview features may be removed in a future release, or upgraded to permanent features of the Java platform. Suspend all virtual threads except those in the exception list. Virtual threads that are currently suspended do not change state. Virtual threads may be resumed with ResumeAllVirtualThreads or ResumeThreadList or ResumeThread.
may only be called during the live phase
No
118
19
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capabilities (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads can_support_virtual_threads Can support virtual threads Parameters Name Type Description except_count jint The number of threads in the list of threads not to be suspended. except_list const jthread * The list of threads not to be suspended. Agent passes in an array of except_count elements of jthread. If except_list is NULL, not an error if except_count == 0. Resume Thread
jvmtiError
ResumeThread(jvmtiEnv* env,
jthread thread)
Resume a suspended thread. Any threads currently suspended through a JVM TI suspend function (eg. SuspendThread) or java.lang.Thread.suspend() will resume execution; all other threads are unaffected.
may only be called during the live phase
No
6
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads Parameters Name Type Description thread jthread The thread to resume. Resume Thread List
jvmtiError
ResumeThreadList(jvmtiEnv* env,
jint request_count,
const jthread* request_list,
jvmtiError* results)
Resume the request_count threads specified in the request_list array. Any thread suspended through a JVM TI suspend function (eg. SuspendThreadList) or java.lang.Thread.suspend() will resume execution.
may only be called during the live phase
No
93
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads Parameters Name Type Description request_count jint The number of threads to resume. request_list const jthread* The threads to resume. Agent passes in an array of request_count elements of jthread. results jvmtiError* An agent supplied array of request_count elements. On return, filled with the error code for the resume of the corresponding thread. The error code will be JVMTI_ERROR_NONE if the thread was suspended by this call. Possible error codes are those specified for ResumeThread. Agent passes an array large enough to hold request_count elements of jvmtiError. The incoming values of the elements of the array are ignored. On return, the elements are set. Resume All Virtual Threads
jvmtiError
ResumeAllVirtualThreads(jvmtiEnv* env,
jint except_count,
const jthread* except_list)
ResumeAllVirtualThreads is a preview API of the Java platform. Preview features may be removed in a future release, or upgraded to permanent features of the Java platform. Resume all virtual threads except those in the exception list. Virtual threads that are currently resumed do not change state. Virtual threads may be suspended with SuspendAllVirtualThreads or SuspendThreadList or SuspendThread.
may only be called during the live phase
No
119
19
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capabilities (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_suspend Can suspend and resume threads can_support_virtual_threads Can support virtual threads Parameters Name Type Description except_count jint The number of threads in the list of threads not to be resumed. except_list const jthread * The list of threads not to be resumed. Agent passes in an array of except_count elements of jthread. If except_list is NULL, not an error if except_count == 0. Stop Thread
jvmtiError
StopThread(jvmtiEnv* env,
jthread thread,
jobject exception)
Send the specified asynchronous exception to the specified platform thread.
may only be called during the live phase
No
7
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_signal_thread Can send stop or interrupt to threads Parameters Name Type Description thread jthread The thread to stop. The thread may not be a virtual thread. Otherwise, the error code JVMTI_ERROR_UNSUPPORTED_OPERATION will be returned. exception jobject The asynchronous exception object. Interrupt Thread
jvmtiError
InterruptThread(jvmtiEnv* env,
jthread thread)
Interrupt the specified thread (similar to java.lang.Thread.interrupt).
may only be called during the live phase
No
8
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_signal_thread Can send stop or interrupt to threads Parameters Name Type Description thread jthread The thread to interrupt. Get Thread Info
Get thread information. The fields of thetypedef struct { char* name; jint priority; jboolean is_daemon; jthreadGroup thread_group; jobject context_class_loader; } jvmtiThreadInfo;jvmtiError GetThreadInfo(jvmtiEnv* env, jthread thread, jvmtiThreadInfo* info_ptr)
jvmtiThreadInfo structure are filled in with details of the specified thread.
may only be called during the live phase
No
9
1.0
Capabilities
Required Functionality
jvmtiThreadInfo - Thread information structure Field Type Description name char* The thread name, encoded as a modified UTF-8 string. priority jint The thread priority. See the thread priority constants: jvmtiThreadPriority. The priority of a virtual thread is always JVMTI_THREAD_NORM_PRIORITY. is_daemon jboolean Is this a daemon thread? The daemon status of a virtual thread is always JNI_TRUE. thread_group jthreadGroup The thread group to which this thread belongs. NULL if the thread has terminated. context_class_loader jobject The context class loader associated with this thread. Parameters Name Type Description thread jthread The thread to query. If thread is NULL, the current thread is used. info_ptr jvmtiThreadInfo* On return, filled with information describing the specified thread. Agent passes a pointer to a jvmtiThreadInfo. On return, the jvmtiThreadInfo has been set. The pointer returned in the field name of jvmtiThreadInfo is a newly allocated array. The array should be freed with Deallocate. The object returned in the field thread_group of jvmtiThreadInfo is a JNI local reference and must be managed. The object returned in the field context_class_loader of jvmtiThreadInfo is a JNI local reference and must be managed. Get Owned Monitor Info
jvmtiError
GetOwnedMonitorInfo(jvmtiEnv* env,
jthread thread,
jint* owned_monitor_count_ptr,
jobject** owned_monitors_ptr)
Get information about the monitors owned by the specified thread.
may only be called during the live phase
No
10
1.0
Parameters Name Type Descriptionthread jthread The thread to query. If thread is NULL, the current thread is used. owned_monitor_count_ptr jint* The number of monitors returned. Agent passes a pointer to a jint. On return, the jint has been set. owned_monitors_ptr jobject** The array of owned monitors. Agent passes a pointer to a jobject*. On return, the jobject* points to a newly allocated array of size *owned_monitor_count_ptr. The array should be freed with Deallocate. The objects returned by owned_monitors_ptr are JNI local references and must be managed. Get Owned Monitor Stack Depth Info
Get information about the monitors owned by the specified thread and the depth of the stack frame which locked them.typedef struct { jobject monitor; jint stack_depth; } jvmtiMonitorStackDepthInfo;jvmtiError GetOwnedMonitorStackDepthInfo(jvmtiEnv* env, jthread thread, jint* monitor_info_count_ptr, jvmtiMonitorStackDepthInfo** monitor_info_ptr)
may only be called during the live phase
No
153
1.1
jvmtiMonitorStackDepthInfo - Monitor stack depth information structure Field Type Description monitor jobject The owned monitor. stack_depth jint The stack depth. Corresponds to the stack depth used in the Stack Frame functions. That is, zero is the current frame, one is the frame which called the current frame. And it is negative one if the implementation cannot determine the stack depth (e.g., for monitors acquired by JNI MonitorEnter). Parameters Name Type Description thread jthread The thread to query. If thread is NULL, the current thread is used. monitor_info_count_ptr jint* The number of monitors returned. Agent passes a pointer to a jint. On return, the jint has been set. monitor_info_ptr jvmtiMonitorStackDepthInfo ** The array of owned monitor depth information. Agent passes a pointer to a jvmtiMonitorStackDepthInfo*. On return, the jvmtiMonitorStackDepthInfo* points to a newly allocated array of size *monitor_info_count_ptr. The array should be freed with Deallocate. The objects returned in the field monitor of jvmtiMonitorStackDepthInfo are JNI local references and must be managed. Get Current Contended Monitor
jvmtiError
GetCurrentContendedMonitor(jvmtiEnv* env,
jthread thread,
jobject* monitor_ptr)
Get the object, if any, whose monitor the specified thread is waiting to enter or waiting to regain through java.lang.Object.wait.
may only be called during the live phase
No
11
1.0
Parameters Name Type Descriptionthread jthread The thread to query. If thread is NULL, the current thread is used. monitor_ptr jobject* On return, filled with the current contended monitor, or NULL if there is none. Agent passes a pointer to a jobject. On return, the jobject has been set. The object returned by monitor_ptr is a JNI local reference and must be managed. Agent Start Function
typedef void (JNICALL *jvmtiStartFunction)
(jvmtiEnv* jvmti_env,
JNIEnv* jni_env,
void* arg);
Agent supplied callback function. This function is the entry point for an agent thread started with
RunAgentThread
.
Parameters Name Type Descriptionjvmti_env jvmtiEnv * The JVM TI environment. jni_env JNIEnv * The JNI environment. arg void * The arg parameter passed to RunAgentThread. Run Agent Thread
jvmtiError
RunAgentThread(jvmtiEnv* env,
jthread thread,
jvmtiStartFunction proc,
const void* arg,
jint priority)
Starts the execution of an agent thread. with the specified native function. The parameter arg is forwarded on to the start function (specified with proc) as its single argument. This function allows the creation of agent threads for handling communication with another process or for handling events without the need to load a special subclass of java.lang.Thread or implementer of java.lang.Runnable. Instead, the created thread can run entirely in native code. However, the created thread does require a newly created instance of java.lang.Thread (referenced by the argument thread) to which it will be associated. The thread object can be created with JNI calls. The following common thread priorities are provided for your convenience:
Thread Priority Constants Constant Value DescriptionThe new thread is started as a daemon thread with the specifiedJVMTI_THREAD_MIN_PRIORITY1 Minimum possible thread priorityJVMTI_THREAD_NORM_PRIORITY5 Normal thread priorityJVMTI_THREAD_MAX_PRIORITY10 Maximum possible thread priority
priority. If enabled, a ThreadStart event will be sent. Since the thread has been started, the thread will be live when this function returns, unless the thread terminated immediately. The thread group of the thread is ignored -- specifically, the thread is not added to the thread group and the thread is not seen on queries of the thread group at either the Java programming language or JVM TI levels. The thread is not visible to Java programming language queries but is included in JVM TI queries (for example, GetAllThreads and GetAllStackTraces). Upon execution of proc, the new thread will be attached to the VM -- see the JNI documentation on Attaching to the VM.
may only be called during the live phase
No
12
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread The thread to run. The thread may not be a virtual thread. Otherwise, the error code JVMTI_ERROR_UNSUPPORTED_OPERATION will be returned. proc jvmtiStartFunction The start function. arg const void * The argument to the start function. Agent passes in a pointer. If arg is NULL, NULL is passed to the start function. priority jint The priority of the started thread. Any thread priority allowed by java.lang.Thread.setPriority can be used including those in jvmtiThreadPriority. Set Thread Local Storage
jvmtiError
SetThreadLocalStorage(jvmtiEnv* env,
jthread thread,
const void* data)
The VM stores a pointer value associated with each environment-thread pair. This pointer value is called thread-local storage. This value is NULL unless set with this function. Agents can allocate memory in which they store thread specific information. By setting thread-local storage it can then be accessed with GetThreadLocalStorage. This function is called by the agent to set the value of the JVM TI thread-local storage. JVM TI supplies to the agent a pointer-size thread-local storage that can be used to record per-thread information.
may only be called during the start or the live phase
No
103
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread Store to this thread. If thread is NULL, the current thread is used. data const void * The value to be entered into the thread-local storage. Agent passes in a pointer. If data is NULL, value is set to NULL. Get Thread Local Storage
jvmtiError
GetThreadLocalStorage(jvmtiEnv* env,
jthread thread,
void** data_ptr)
Called by the agent to get the value of the JVM TI thread-local storage.
may only be called during the start or the live phase
No
102
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread Retrieve from this thread. If thread is NULL, the current thread is used. data_ptr void** Pointer through which the value of the thread local storage is returned. If thread-local storage has not been set with SetThreadLocalStorage the returned pointer is NULL. Thread Group Thread Group functions:
Thread Group types:
jvmtiThreadGroupInfo - Thread group information structure
jvmtiError
GetTopThreadGroups(jvmtiEnv* env,
jint* group_count_ptr,
jthreadGroup** groups_ptr)
Return all top-level (parentless) thread groups in the VM.
may only be called during the live phase
No
13
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptiongroup_count_ptr jint* On return, points to the number of top-level thread groups. Agent passes a pointer to a jint. On return, the jint has been set. groups_ptr jthreadGroup** On return, refers to a pointer to the top-level thread group array. Agent passes a pointer to a jthreadGroup*. On return, the jthreadGroup* points to a newly allocated array of size *group_count_ptr. The array should be freed with Deallocate. The objects returned by groups_ptr are JNI local references and must be managed. Get Thread Group Info
Get information about the thread group. The fields of thetypedef struct { jthreadGroup parent; char* name; jint max_priority; jboolean is_daemon; } jvmtiThreadGroupInfo;jvmtiError GetThreadGroupInfo(jvmtiEnv* env, jthreadGroup group, jvmtiThreadGroupInfo* info_ptr)
jvmtiThreadGroupInfo structure are filled in with details of the specified thread group.
may only be called during the live phase
No
14
1.0
Capabilities
Required Functionality
jvmtiThreadGroupInfo - Thread group information structure Field Type Description parent jthreadGroup The parent thread group. name char* The thread group's name, encoded as a modified UTF-8 string. max_priority jint The maximum priority for this thread group. is_daemon jboolean Is this a daemon thread group? Parameters Name Type Description group jthreadGroup The thread group to query. info_ptr jvmtiThreadGroupInfo* On return, filled with information describing the specified thread group. Agent passes a pointer to a jvmtiThreadGroupInfo. On return, the jvmtiThreadGroupInfo has been set. The object returned in the field parent of jvmtiThreadGroupInfo is a JNI local reference and must be managed. The pointer returned in the field name of jvmtiThreadGroupInfo is a newly allocated array. The array should be freed with Deallocate. Get Thread Group Children
jvmtiError
GetThreadGroupChildren(jvmtiEnv* env,
jthreadGroup group,
jint* thread_count_ptr,
jthread** threads_ptr,
jint* group_count_ptr,
jthreadGroup** groups_ptr)
Get the live platform threads and the child thread groups in this thread group. Virtual threads are not returned by this function.
may only be called during the live phase
No
15
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptiongroup jthreadGroup The group to query. thread_count_ptr jint* On return, points to the number of live threads in this thread group. Agent passes a pointer to a jint. On return, the jint has been set. threads_ptr jthread** On return, points to an array of the live threads in this thread group. Agent passes a pointer to a jthread*. On return, the jthread* points to a newly allocated array of size *thread_count_ptr. The array should be freed with Deallocate. The objects returned by threads_ptr are JNI local references and must be managed. group_count_ptr jint* On return, points to the number of child thread groups Agent passes a pointer to a jint. On return, the jint has been set. groups_ptr jthreadGroup** On return, points to an array of the child thread groups. Agent passes a pointer to a jthreadGroup*. On return, the jthreadGroup* points to a newly allocated array of size *group_count_ptr. The array should be freed with Deallocate. The objects returned by groups_ptr are JNI local references and must be managed. Stack Frame Stack Frame functions:
jvmtiFrameInfo - Stack frame information structurejvmtiStackInfo - Stack information structuremain() and run(). However this presentation must be consistent across all JVM TI functionality which uses stack frames or stack depth. Stack frame information structure Information about a stack frame is returned in this structure.
Stack information structure Information about a set of stack frames is returned in this structure.typedef struct { jmethodID method; jlocation location; } jvmtiFrameInfo;jvmtiFrameInfo- Stack frame information structure Field Type DescriptionmethodjmethodIDThe method executing in this frame.locationjlocationThe index of the instruction executing in this frame.-1if the frame is executing a native method.
Get Stack Tracetypedef struct { jthread thread; jint state; jvmtiFrameInfo* frame_buffer; jint frame_count; } jvmtiStackInfo;jvmtiStackInfo- Stack information structure Field Type DescriptionthreadjthreadOn return, the thread traced.statejintOn return, the thread state. SeeGetThreadState.frame_bufferjvmtiFrameInfo *On return, this agent allocated buffer is filled with stack frame information.frame_countjintOn return, the number of records filled intoframe_buffer. This will be min(max_frame_count, stackDepth).
jvmtiError
GetStackTrace(jvmtiEnv* env,
jthread thread,
jint start_depth,
jint max_frame_count,
jvmtiFrameInfo* frame_buffer,
jint* count_ptr)
Get information about the stack of a thread. If max_frame_count is less than the depth of the stack, the max_frame_count topmost frames are returned, otherwise the entire stack is returned. The topmost frames, those most recently invoked, are at the beginning of the returned buffer. The following example causes up to five of the topmost frames to be returned and (if there are any frames) the currently executing method name to be printed.
jvmtiFrameInfo frames[5];
jint count;
jvmtiError err;
err = (*jvmti)->GetStackTrace(jvmti, aThread, 0, 5,
frames, &count);
if (err == JVMTI_ERROR_NONE && count >= 1) {
char *methodName;
err = (*jvmti)->GetMethodName(jvmti, frames[0].method,
&methodName, NULL, NULL);
if (err == JVMTI_ERROR_NONE) {
printf("Executing method: %s", methodName);
}
}
The thread need not be suspended to call this function. The GetLineNumberTable function can be used to map locations to line numbers. Note that this mapping can be done lazily.
may only be called during the live phase
No
104
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread Fetch the stack trace of this thread. If thread is NULL, the current thread is used. start_depth jint Begin retrieving frames at this depth. If non-negative, count from the current frame, the first frame retrieved is at depth start_depth. For example, if zero, start from the current frame; if one, start from the caller of the current frame; if two, start from the caller of the caller of the current frame; and so on. If negative, count from below the oldest frame, the first frame retrieved is at depth stackDepth + start_depth, where stackDepth is the count of frames on the stack. For example, if negative one, only the oldest frame is retrieved; if negative two, start from the frame called by the oldest frame. max_frame_count jint The maximum number of jvmtiFrameInfo records to retrieve. frame_buffer jvmtiFrameInfo * On return, this agent allocated buffer is filled with stack frame information. Agent passes an array large enough to hold max_frame_count elements of jvmtiFrameInfo. The incoming values of the elements of the array are ignored. On return, *count_ptr of the elements are set. count_ptr jint* On return, points to the number of records filled in. For non-negative start_depth, this will be min(max_frame_count, stackDepth - start_depth). For negative start_depth, this will be min(max_frame_count, -start_depth). Agent passes a pointer to a jint. On return, the jint has been set. Get All Stack Traces
jvmtiError
GetAllStackTraces(jvmtiEnv* env,
jint max_frame_count,
jvmtiStackInfo** stack_info_ptr,
jint* thread_count_ptr)
Get the stack traces of all live platform threads attached to the VM. The list includes the stack traces of agent threads. It does not include the stack traces of virtual threads. If max_frame_count is less than the depth of a stack, the max_frame_count topmost frames are returned for that thread, otherwise the entire stack is returned. The topmost frames, those most recently invoked, are at the beginning of the returned buffer. All stacks are collected simultaneously, that is, no changes will occur to the thread state or stacks between the sampling of one thread and the next. The threads need not be suspended.
jvmtiStackInfo *stack_info;
jint thread_count;
int ti;
jvmtiError err;
err = (*jvmti)->GetAllStackTraces(jvmti, MAX_FRAMES, &stack_info, &thread_count);
if (err != JVMTI_ERROR_NONE) {
...
}
for (ti = 0; ti < thread_count; ++ti) {
jvmtiStackInfo *infop = &stack_info[ti];
jthread thread = infop->thread;
jint state = infop->state;
jvmtiFrameInfo *frames = infop->frame_buffer;
int fi;
myThreadAndStatePrinter(thread, state);
for (fi = 0; fi < infop->frame_count; fi++) {
myFramePrinter(frames[fi].method, frames[fi].location);
}
}
/* this one Deallocate call frees all data allocated by GetAllStackTraces */
err = (*jvmti)->Deallocate(jvmti, stack_info);
may only be called during the live phase
No
100
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmax_frame_count jint The maximum number of jvmtiFrameInfo records to retrieve per thread. stack_info_ptr jvmtiStackInfo ** On return, this buffer is filled with stack information for each thread. The number of jvmtiStackInfo records is determined by thread_count_ptr. Note that this buffer is allocated to include the jvmtiFrameInfo buffers pointed to by jvmtiStackInfo.frame_buffer. These buffers must not be separately deallocated. Agent passes a pointer to a jvmtiStackInfo*. On return, the jvmtiStackInfo* points to a newly allocated array. The array should be freed with Deallocate. The objects returned in the field thread of jvmtiStackInfo are JNI local references and must be managed. thread_count_ptr jint* The number of threads traced. Agent passes a pointer to a jint. On return, the jint has been set. Get Thread List Stack Traces
jvmtiError
GetThreadListStackTraces(jvmtiEnv* env,
jint thread_count,
const jthread* thread_list,
jint max_frame_count,
jvmtiStackInfo** stack_info_ptr)
Get information about the stacks of the supplied threads. If max_frame_count is less than the depth of a stack, the max_frame_count topmost frames are returned for that thread, otherwise the entire stack is returned. The topmost frames, those most recently invoked, are at the beginning of the returned buffer. All stacks are collected simultaneously, that is, no changes will occur to the thread state or stacks between the sampling one thread and the next. The threads need not be suspended. If a thread has not yet started or terminates before the stack information is collected, a zero length stack (jvmtiStackInfo.frame_count will be zero) will be returned and the thread jvmtiStackInfo.state can be checked. See the example for the similar function GetAllStackTraces.
may only be called during the live phase
No
101
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread_count jint The number of threads to trace. thread_list const jthread* The list of threads to trace. Agent passes in an array of thread_count elements of jthread. max_frame_count jint The maximum number of jvmtiFrameInfo records to retrieve per thread. stack_info_ptr jvmtiStackInfo ** On return, this buffer is filled with stack information for each thread. The number of jvmtiStackInfo records is determined by thread_count. Note that this buffer is allocated to include the jvmtiFrameInfo buffers pointed to by jvmtiStackInfo.frame_buffer. These buffers must not be separately deallocated. Agent passes a pointer to a jvmtiStackInfo*. On return, the jvmtiStackInfo* points to a newly allocated array of size *thread_count. The array should be freed with Deallocate. The objects returned in the field thread of jvmtiStackInfo are JNI local references and must be managed. Get Frame Count
jvmtiError
GetFrameCount(jvmtiEnv* env,
jthread thread,
jint* count_ptr)
Get the number of frames currently in the specified thread's call stack. If this function is called for a thread actively executing bytecodes (for example, not the current thread and not suspended), the information returned is transient.
may only be called during the live phase
No
16
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread The thread to query. If thread is NULL, the current thread is used. count_ptr jint* On return, points to the number of frames in the call stack. Agent passes a pointer to a jint. On return, the jint has been set. Pop Frame
jvmtiError
PopFrame(jvmtiEnv* env,
jthread thread)
Pop the current frame of thread's stack. Popping a frame takes you to the previous frame. When the thread is resumed, the execution state of the thread is reset to the state immediately before the called method was invoked. That is (using The Java™ Virtual Machine Specification terminology):
invokestatic, objectref is added back as wellPopFrame and resuming the thread the state of the stack is undefined. To pop frames beyond the first, these three steps must be repeated:
PopFramesynchronized method) and locks acquired by entering synchronized blocks within the called method are released. Note: this does not apply to native locks or java.util.concurrent.locks locks. Finally blocks are not executed. Changes to global state are not addressed and thus remain changed. The specified thread must be suspended or must be the current thread. Both the called method and calling method must be non-native Java programming language methods. No JVM TI events are generated by this function.
may only be called during the live phase
No
80
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_pop_frame Can pop frames off the stack - PopFrame Parameters Name Type Description thread jthread The thread whose current frame is to be popped. Get Frame Location
jvmtiError
GetFrameLocation(jvmtiEnv* env,
jthread thread,
jint depth,
jmethodID* method_ptr,
jlocation* location_ptr)
For a Java programming language frame, return the location of the instruction currently executing.
may only be called during the live phase
No
19
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionthread jthread The thread of the frame to query. If thread is NULL, the current thread is used. depth jint The depth of the frame to query. method_ptr jmethodID* On return, points to the method for the current location. Agent passes a pointer to a jmethodID. On return, the jmethodID has been set. location_ptr jlocation* On return, points to the index of the currently executing instruction. Is set to -1 if the frame is executing a native method. Agent passes a pointer to a jlocation. On return, the jlocation has been set. Notify Frame Pop
jvmtiError
NotifyFramePop(jvmtiEnv* env,
jthread thread,
jint depth)
When the frame that is currently at depth is popped from the stack, generate a FramePop event. See the FramePop event for details. Only frames corresponding to non-native Java programming language methods can receive notification. The specified thread must be suspended or must be the current thread.
may only be called during the live phase
No
20
1.0
Parameters Name Type Descriptionthread jthread The thread of the frame for which the frame pop event will be generated. If thread is NULL, the current thread is used. depth jint The depth of the frame for which the frame pop event will be generated. Force Early Return Force Early Return functions:
synchronized method) and locks acquired by entering synchronized blocks within the called method are released. Note: this does not apply to native locks or java.util.concurrent.locks locks. Events, such as MethodExit, are generated as they would be in a normal return. The called method must be a non-native Java programming language method. Forcing return on a thread with only one frame on the stack causes the thread to exit when resumed. Force Early Return - Object
jvmtiError
ForceEarlyReturnObject(jvmtiEnv* env,
jthread thread,
jobject value)
This function can be used to return from a method whose result type is Object or a subclass of Object.
may only be called during the live phase
No
81
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. value jobject The return value for the called frame. An object or NULL. Force Early Return - Int
jvmtiError
ForceEarlyReturnInt(jvmtiEnv* env,
jthread thread,
jint value)
This function can be used to return from a method whose result type is int, short, char, byte, or boolean.
may only be called during the live phase
No
82
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. value jint The return value for the called frame. Force Early Return - Long
jvmtiError
ForceEarlyReturnLong(jvmtiEnv* env,
jthread thread,
jlong value)
This function can be used to return from a method whose result type is long.
may only be called during the live phase
No
83
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. value jlong The return value for the called frame. Force Early Return - Float
jvmtiError
ForceEarlyReturnFloat(jvmtiEnv* env,
jthread thread,
jfloat value)
This function can be used to return from a method whose result type is float.
may only be called during the live phase
No
84
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. value jfloat The return value for the called frame. Force Early Return - Double
jvmtiError
ForceEarlyReturnDouble(jvmtiEnv* env,
jthread thread,
jdouble value)
This function can be used to return from a method whose result type is double.
may only be called during the live phase
No
85
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. value jdouble The return value for the called frame. Force Early Return - Void
jvmtiError
ForceEarlyReturnVoid(jvmtiEnv* env,
jthread thread)
This function can be used to return from a method with no result type. That is, the called method must be declared void.
may only be called during the live phase
No
86
1.1
Parameters Name Type Descriptionthread jthread The thread whose current frame is to return early. If thread is NULL, the current thread is used. Heap Heap functions:
jvmtiHeapReferenceKind - Heap Reference EnumerationjvmtiPrimitiveType - Primitive Type EnumerationjvmtiHeapReferenceInfoField - Reference information structure for Field referencesjvmtiHeapReferenceInfoArray - Reference information structure for Array referencesjvmtiHeapReferenceInfoConstantPool - Reference information structure for Constant Pool referencesjvmtiHeapReferenceInfoStackLocal - Reference information structure for Local Variable referencesjvmtiHeapReferenceInfoJniLocal - Reference information structure for JNI local referencesjvmtiHeapReferenceInfoReserved - Reference information structure for Other referencesjvmtiHeapReferenceInfo - Reference information structurejvmtiHeapCallbacks - Heap callback function structureSetTag function or by callback functions such as jvmtiHeapIterationCallback. Tags are local to the environment; that is, the tags of one environment are not visible in another. Tags are jlong values which can be used simply to mark an object or to store a pointer to more detailed information. Objects which have not been tagged have a tag of zero. Setting a tag to zero makes the object untagged. Heap Callback Functions Heap functions which iterate through the heap and recursively follow object references use agent supplied callback functions to deliver the information. These heap callback functions must adhere to the following restrictions -- These callbacks must not use JNI functions. These callbacks must not use JVM TI functions except callback safe functions which specifically allow such use (see the raw monitor, memory management, and environment local storage functions). An implementation may invoke a callback on an internal thread or the thread which called the iteration function. Heap callbacks are single threaded -- no more than one callback will be invoked at a time. The Heap Filter Flags can be used to prevent reporting based on the tag status of an object or its class. If no flags are set (the jint is zero), objects will not be filtered out.
Heap Filter Flags Constant Value DescriptionThe Heap Visit Control Flags are returned by the heap callbacks and can be used to abort the iteration. For the Heap Reference Callback, it can also be used to prune the graph of traversed references (JVMTI_HEAP_FILTER_TAGGED0x4 Filter out tagged objects. Objects which are tagged are not included.JVMTI_HEAP_FILTER_UNTAGGED0x8 Filter out untagged objects. Objects which are not tagged are not included.JVMTI_HEAP_FILTER_CLASS_TAGGED0x10 Filter out objects with tagged classes. Objects whose class is tagged are not included.JVMTI_HEAP_FILTER_CLASS_UNTAGGED0x20 Filter out objects with untagged classes. Objects whose class is not tagged are not included.
JVMTI_VISIT_OBJECTS is not set).
Heap Visit Control Flags Constant Value DescriptionThe Heap Reference Enumeration is provided by the Heap Reference Callback and Primitive Field Callback to describe the kind of reference being reported.JVMTI_VISIT_OBJECTS0x100 If we are visiting an object and if this callback was initiated byFollowReferences, traverse the references of this object. Otherwise ignored.JVMTI_VISIT_ABORT0x8000 Abort the iteration. Ignore all other bits.
Heap Reference Enumeration (Definitions for the single character type descriptors of primitive types.jvmtiHeapReferenceKind) Constant Value DescriptionJVMTI_HEAP_REFERENCE_CLASS1 Reference from an object to its class.JVMTI_HEAP_REFERENCE_FIELD2 Reference from an object to the value of one of its instance fields.JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT3 Reference from an array to one of its elements.JVMTI_HEAP_REFERENCE_CLASS_LOADER4 Reference from a class to its class loader.JVMTI_HEAP_REFERENCE_SIGNERS5 Reference from a class to its signers array.JVMTI_HEAP_REFERENCE_PROTECTION_DOMAIN6 Reference from a class to its protection domain.JVMTI_HEAP_REFERENCE_INTERFACE7 Reference from a class to one of its interfaces. Note: interfaces are defined via a constant pool reference, so the referenced interfaces may also be reported with aJVMTI_HEAP_REFERENCE_CONSTANT_POOLreference kind.JVMTI_HEAP_REFERENCE_STATIC_FIELD8 Reference from a class to the value of one of its static fields.JVMTI_HEAP_REFERENCE_CONSTANT_POOL9 Reference from a class to a resolved entry in the constant pool.JVMTI_HEAP_REFERENCE_SUPERCLASS10 Reference from a class to its superclass. A callback is not sent if the superclass isjava.lang.Object. Note: loaded classes define superclasses via a constant pool reference, so the referenced superclass may also be reported with aJVMTI_HEAP_REFERENCE_CONSTANT_POOLreference kind.JVMTI_HEAP_REFERENCE_JNI_GLOBAL21 Heap root reference: JNI global reference.JVMTI_HEAP_REFERENCE_SYSTEM_CLASS22 Heap root reference: System class.JVMTI_HEAP_REFERENCE_MONITOR23 Heap root reference: monitor.JVMTI_HEAP_REFERENCE_STACK_LOCAL24 Heap root reference: local variable on the stack.JVMTI_HEAP_REFERENCE_JNI_LOCAL25 Heap root reference: JNI local reference.JVMTI_HEAP_REFERENCE_THREAD26 Heap root reference: Thread.JVMTI_HEAP_REFERENCE_OTHER27 Heap root reference: other heap root reference.
Primitive Type Enumeration (Reference information structure for Field references Reference information returned forjvmtiPrimitiveType) Constant Value DescriptionJVMTI_PRIMITIVE_TYPE_BOOLEAN90 'Z' - Java programming languageboolean- JNIjbooleanJVMTI_PRIMITIVE_TYPE_BYTE66 'B' - Java programming languagebyte- JNIjbyteJVMTI_PRIMITIVE_TYPE_CHAR67 'C' - Java programming languagechar- JNIjcharJVMTI_PRIMITIVE_TYPE_SHORT83 'S' - Java programming languageshort- JNIjshortJVMTI_PRIMITIVE_TYPE_INT73 'I' - Java programming languageint- JNIjintJVMTI_PRIMITIVE_TYPE_LONG74 'J' - Java programming languagelong- JNIjlongJVMTI_PRIMITIVE_TYPE_FLOAT70 'F' - Java programming languagefloat- JNIjfloatJVMTI_PRIMITIVE_TYPE_DOUBLE68 'D' - Java programming languagedouble- JNIjdouble
JVMTI_HEAP_REFERENCE_FIELD and JVMTI_HEAP_REFERENCE_STATIC_FIELD references.
Reference information structure for Array references Reference information returned fortypedef struct { jint index; } jvmtiHeapReferenceInfoField;jvmtiHeapReferenceInfoField- Reference information structure for Field references Field Type DescriptionindexjintForJVMTI_HEAP_REFERENCE_FIELD, the referrer object is not a class or an interface. In this case,indexis the index of the field in the class of the referrer object. This class is referred to below as C. ForJVMTI_HEAP_REFERENCE_STATIC_FIELD, the referrer object is a class (referred to below as C) or an interface (referred to below as I). In this case,indexis the index of the field in that class or interface. If the referrer object is not an interface, then the field indices are determined as follows:If the referrer object is an interface, then the field indices are determined as follows:
- make a list of all the fields in C and its superclasses, starting with all the fields in
java.lang.Objectand ending with all the fields in C.- Within this list, put the fields for a given class in the order returned by
GetClassFields.- Assign the fields in this list indices n, n+1, ..., in order, where n is the count of the fields in all the interfaces implemented by C. Note that C implements all interfaces directly implemented by its superclasses; as well as all superinterfaces of these interfaces.
All fields are included in this computation, regardless of field modifier (static, public, private, etc). For example, given the following classes and interfaces:
- make a list of the fields directly declared in I.
- Within this list, put the fields in the order returned by
GetClassFields.- Assign the fields in this list indices n, n+1, ..., in order, where n is the count of the fields in all the superinterfaces of I.
Assume thatinterface I0 { int p = 0; } interface I1 extends I0 { int x = 1; } interface I2 extends I0 { int y = 2; } class C1 implements I1 { public static int a = 3; private int b = 4; } class C2 extends C1 implements I2 { static int q = 5; final int r = 6; }GetClassFieldscalled onC1returns the fields ofC1in the order: a, b; and that the fields ofC2are returned in the order: q, r. An instance of classC1will have the following field indices:Field Index Description a 2 The count of the fields in the interfaces implemented byThe classC1is two (n=2):pofI0andxofI1. b 3 the subsequent index.C1will have the same field indices. An instance of classC2will have the following field indices:Field Index Description a 3 The count of the fields in the interfaces implemented byThe classC2is three (n=3):pofI0,xofI1andyofI2(an interface ofC2). Note that the fieldpofI0is only included once. b 4 the subsequent index to "a". q 5 the subsequent index to "b". r 6 the subsequent index to "q".C2will have the same field indices. Note that a field may have a different index depending on the object that is viewing it -- for example field "a" above. Note also: not all field indices may be visible from the callbacks, but all indices are shown for illustrative purposes. The interfaceI1will have the following field indices:Field Index Description x 1 The count of the fields in the superinterfaces ofI1is one (n=1):pofI0.
JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT references.
Reference information structure for Constant Pool references Reference information returned fortypedef struct { jint index; } jvmtiHeapReferenceInfoArray;jvmtiHeapReferenceInfoArray- Reference information structure for Array references Field Type DescriptionindexjintThe array index.
JVMTI_HEAP_REFERENCE_CONSTANT_POOL references.
Reference information structure for Local Variable references Reference information returned fortypedef struct { jint index; } jvmtiHeapReferenceInfoConstantPool;jvmtiHeapReferenceInfoConstantPool- Reference information structure for Constant Pool references Field Type DescriptionindexjintThe index into the constant pool of the class. See the description in The Java™ Virtual Machine Specification, Chapter 4.4.
JVMTI_HEAP_REFERENCE_STACK_LOCAL references.
Reference information structure for JNI local references Reference information returned fortypedef struct { jlong thread_tag; jlong thread_id; jint depth; jmethodID method; jlocation location; jint slot; } jvmtiHeapReferenceInfoStackLocal;jvmtiHeapReferenceInfoStackLocal- Reference information structure for Local Variable references Field Type Descriptionthread_tagjlongThe tag of the thread corresponding to this stack, zero if not tagged.thread_idjlongThe unique thread ID of the thread corresponding to this stack.depthjintThe depth of the frame.methodjmethodIDThe method executing in this frame.locationjlocationThe currently executing location in this frame.slotjintThe slot number of the local variable.
JVMTI_HEAP_REFERENCE_JNI_LOCAL references.
Reference information structure for Other references Reference information returned for other references.typedef struct { jlong thread_tag; jlong thread_id; jint depth; jmethodID method; } jvmtiHeapReferenceInfoJniLocal;jvmtiHeapReferenceInfoJniLocal- Reference information structure for JNI local references Field Type Descriptionthread_tagjlongThe tag of the thread corresponding to this stack, zero if not tagged.thread_idjlongThe unique thread ID of the thread corresponding to this stack.depthjintThe depth of the frame.methodjmethodIDThe method executing in this frame.
Reference information structure The information returned about referrers. Represented as a union of the various kinds of reference information.typedef struct { jlong reserved1; jlong reserved2; jlong reserved3; jlong reserved4; jlong reserved5; jlong reserved6; jlong reserved7; jlong reserved8; } jvmtiHeapReferenceInfoReserved;jvmtiHeapReferenceInfoReserved- Reference information structure for Other references Field Type Descriptionreserved1jlongreserved for future use.reserved2jlongreserved for future use.reserved3jlongreserved for future use.reserved4jlongreserved for future use.reserved5jlongreserved for future use.reserved6jlongreserved for future use.reserved7jlongreserved for future use.reserved8jlongreserved for future use.
typedef union {
jvmtiHeapReferenceInfoField field;
jvmtiHeapReferenceInfoArray array;
jvmtiHeapReferenceInfoConstantPool constant_pool;
jvmtiHeapReferenceInfoStackLocal stack_local;
jvmtiHeapReferenceInfoJniLocal jni_local;
jvmtiHeapReferenceInfoReserved other;
} jvmtiHeapReferenceInfo;
Heap callback function structure
typedef struct {
jvmtiHeapIterationCallback heap_iteration_callback;
jvmtiHeapReferenceCallback heap_reference_callback;
jvmtiPrimitiveFieldCallback primitive_field_callback;
jvmtiArrayPrimitiveValueCallback array_primitive_value_callback;
jvmtiStringPrimitiveValueCallback string_primitive_value_callback;
jvmtiReservedCallback reserved5;
jvmtiReservedCallback reserved6;
jvmtiReservedCallback reserved7;
jvmtiReservedCallback reserved8;
jvmtiReservedCallback reserved9;
jvmtiReservedCallback reserved10;
jvmtiReservedCallback reserved11;
jvmtiReservedCallback reserved12;
jvmtiReservedCallback reserved13;
jvmtiReservedCallback reserved14;
jvmtiReservedCallback reserved15;
} jvmtiHeapCallbacks;
Rationale: The heap dumping functionality (below) uses a callback for each object. While it would seem that a buffered approach would provide better throughput, tests do not show this to be the case--possibly due to locality of memory reference or array access overhead.
Heap Iteration Callback
typedef jint (JNICALL *jvmtiHeapIterationCallback)
(jlong class_tag,
jlong size,
jlong* tag_ptr,
jint length,
void* user_data);
Agent supplied callback function. Describes (but does not pass in) an object in the heap.
This function should return a bit vector of the desired
visit control flags. This will determine if the entire iteration should be aborted (the
JVMTI_VISIT_OBJECTS
flag is ignored).
See the
heap callback function restrictions.
Parameters Name Type Descriptionclass_tag jlong The tag of the class of object (zero if the class is not tagged). If the object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the object (in bytes). See GetObjectSize. tag_ptr jlong* The object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. length jint If this object is an array, the length of the array. Otherwise negative one (-1). user_data void* The user supplied data that was passed into the iteration function. Heap Reference Callback
typedef jint (JNICALL *jvmtiHeapReferenceCallback)
(jvmtiHeapReferenceKind reference_kind,
const jvmtiHeapReferenceInfo* reference_info,
jlong class_tag,
jlong referrer_class_tag,
jlong size,
jlong* tag_ptr,
jlong* referrer_tag_ptr,
jint length,
void* user_data);
Agent supplied callback function. Describes a reference from an object or the VM (the referrer) to another object (the referree) or a heap root to a referree.
This function should return a bit vector of the desired
visit control flags. This will determine if the objects referenced by the referree should be visited or if the entire iteration should be aborted.
See the
heap callback function restrictions.
Parameters Name Type Descriptionreference_kind jvmtiHeapReferenceKind The kind of reference. reference_info const jvmtiHeapReferenceInfo * Details about the reference. Set when the reference_kind is JVMTI_HEAP_REFERENCE_FIELD, JVMTI_HEAP_REFERENCE_STATIC_FIELD, JVMTI_HEAP_REFERENCE_ARRAY_ELEMENT, JVMTI_HEAP_REFERENCE_CONSTANT_POOL, JVMTI_HEAP_REFERENCE_STACK_LOCAL, or JVMTI_HEAP_REFERENCE_JNI_LOCAL. Otherwise NULL. class_tag jlong The tag of the class of referree object (zero if the class is not tagged). If the referree object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). referrer_class_tag jlong The tag of the class of the referrer object (zero if the class is not tagged or the referree is a heap root). If the referrer object represents a runtime class, the referrer_class_tag is the tag associated with the java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the referree object (in bytes). See GetObjectSize. tag_ptr jlong* Points to the referree object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. referrer_tag_ptr jlong* Points to the tag of the referrer object, or points to the zero if the referrer object is not tagged. NULL if the referrer in not an object (that is, this callback is reporting a heap root). To set the tag value to be associated with the referrer object the agent sets the jlong pointed to by the parameter. If this callback is reporting a reference from an object to itself, referrer_tag_ptr == tag_ptr. length jint If this object is an array, the length of the array. Otherwise negative one (-1). user_data void* The user supplied data that was passed into the iteration function. Primitive Field Callback
typedef jint (JNICALL *jvmtiPrimitiveFieldCallback)
(jvmtiHeapReferenceKind kind,
const jvmtiHeapReferenceInfo* info,
jlong object_class_tag,
jlong* object_tag_ptr,
jvalue value,
jvmtiPrimitiveType value_type,
void* user_data);
Agent supplied callback function which describes a primitive field of an object (
the object). A primitive field is a field whose type is a primitive type. This callback will describe a static field if the object is a class, and otherwise will describe an instance field.
This function should return a bit vector of the desired
visit control flags. This will determine if the entire iteration should be aborted (the
JVMTI_VISIT_OBJECTS
flag is ignored).
See the
heap callback function restrictions.
Parameters Name Type Descriptionkind jvmtiHeapReferenceKind The kind of field -- instance or static (JVMTI_HEAP_REFERENCE_FIELD or JVMTI_HEAP_REFERENCE_STATIC_FIELD). info const jvmtiHeapReferenceInfo * Which field (the field index). object_class_tag jlong The tag of the class of the object (zero if the class is not tagged). If the object represents a runtime class, the object_class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). object_tag_ptr jlong* Points to the tag of the object, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. value jvalue The value of the field. value_type jvmtiPrimitiveType The type of the field. user_data void* The user supplied data that was passed into the iteration function. Array Primitive Value Callback
typedef jint (JNICALL *jvmtiArrayPrimitiveValueCallback)
(jlong class_tag,
jlong size,
jlong* tag_ptr,
jint element_count,
jvmtiPrimitiveType element_type,
const void* elements,
void* user_data);
Agent supplied callback function. Describes the values in an array of a primitive type.
This function should return a bit vector of the desired
visit control flags. This will determine if the entire iteration should be aborted (the
JVMTI_VISIT_OBJECTS
flag is ignored).
See the
heap callback function restrictions.
Parameters Name Type Descriptionclass_tag jlong The tag of the class of the array object (zero if the class is not tagged). size jlong Size of the array (in bytes). See GetObjectSize. tag_ptr jlong* Points to the tag of the array object, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. element_count jint The length of the primitive array. element_type jvmtiPrimitiveType The type of the elements of the array. elements const void* The elements of the array in a packed array of element_count items of element_type size each. user_data void* The user supplied data that was passed into the iteration function. String Primitive Value Callback
typedef jint (JNICALL *jvmtiStringPrimitiveValueCallback)
(jlong class_tag,
jlong size,
jlong* tag_ptr,
const jchar* value,
jint value_length,
void* user_data);
Agent supplied callback function. Describes the value of a java.lang.String.
This function should return a bit vector of the desired
visit control flags. This will determine if the entire iteration should be aborted (the
JVMTI_VISIT_OBJECTS
flag is ignored).
See the
heap callback function restrictions.
Parameters Name Type Descriptionclass_tag jlong The tag of the class of the String class (zero if the class is not tagged). size jlong Size of the string (in bytes). See GetObjectSize. tag_ptr jlong* Points to the tag of the String object, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. value const jchar* The value of the String, encoded as a Unicode string. value_length jint The length of the string. The length is equal to the number of 16-bit Unicode characters in the string. user_data void* The user supplied data that was passed into the iteration function. reserved for future use Callback
typedef jint (JNICALL *jvmtiReservedCallback)
();
Placeholder -- reserved for future use.
Follow References
jvmtiError
FollowReferences(jvmtiEnv* env,
jint heap_filter,
jclass klass,
jobject initial_object,
const jvmtiHeapCallbacks* callbacks,
const void* user_data)
This function initiates a traversal over the objects that are directly and indirectly reachable from the specified object or, if initial_object is not specified, all objects reachable from the heap roots. The heap root are the set of system classes, JNI globals, references from thread stacks, and other objects used as roots for the purposes of garbage collection. This function operates by traversing the reference graph. Let A, B, ... represent objects. When a reference from A to B is traversed, when a reference from a heap root to B is traversed, or when B is specified as the initial_object, then B is said to be visited. A reference from A to B is not traversed until A is visited. References are reported in the same order that the references are traversed. Object references are reported by invoking the agent supplied callback function jvmtiHeapReferenceCallback. In a reference from A to B, A is known as the referrer and B as the referree. The callback is invoked exactly once for each reference from a referrer; this is true even if there are reference cycles or multiple paths to the referrer. There may be more than one reference between a referrer and a referree, each reference is reported. These references may be distinguished by examining the reference_kind and reference_info parameters of the jvmtiHeapReferenceCallback callback. This function reports a Java programming language view of object references, not a virtual machine implementation view. The following object references are reported when they are non-null:
jvmtiArrayPrimitiveValueCallback or jvmtiStringPrimitiveValueCallback. A primitive field is reported after the object with that field is visited; it is reported by invoking the agent supplied callback function jvmtiPrimitiveFieldCallback. Whether a callback is provided or is NULL only determines whether the callback will be invoked, it does not influence which objects are visited nor does it influence whether other callbacks will be invoked. However, the visit control flags returned by jvmtiHeapReferenceCallback do determine if the objects referenced by the current object as visited. The heap filter flags and klass provided as parameters to this function do not control which objects are visited but they do control which objects and primitive values are reported by the callbacks. For example, if the only callback that was set is array_primitive_value_callback and klass is set to the array of bytes class, then only arrays of byte will be reported. The table below summarizes this: During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
115
1.1
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description heap_filter jint This bit vector of heap filter flags. restricts the objects for which the callback function is called. This applies to both the object and primitive callbacks. klass jclass Callbacks are only reported when the object is an instance of this class. Objects which are instances of a subclass of klass are not reported. If klass is an interface, no objects are reported. This applies to both the object and primitive callbacks. If klass is NULL, callbacks are not limited to instances of a particular class. initial_object jobject The object to follow If initial_object is NULL, references are followed from the heap roots. callbacks const jvmtiHeapCallbacks * Structure defining the set of callback functions. Agent passes in a pointer to jvmtiHeapCallbacks. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Iterate Through Heap
jvmtiError
IterateThroughHeap(jvmtiEnv* env,
jint heap_filter,
jclass klass,
const jvmtiHeapCallbacks* callbacks,
const void* user_data)
Initiate an iteration over all objects in the heap. This includes both reachable and unreachable objects. Objects are visited in no particular order. Heap objects are reported by invoking the agent supplied callback function jvmtiHeapIterationCallback. References between objects are not reported. If only reachable objects are desired, or if object reference information is needed, use FollowReferences. This function can also be used to examine primitive (non-object) values. The primitive value of an array or String is reported after the object has been visited; it is reported by invoking the agent supplied callback function jvmtiArrayPrimitiveValueCallback or jvmtiStringPrimitiveValueCallback. A primitive field is reported after the object with that field is visited; it is reported by invoking the agent supplied callback function jvmtiPrimitiveFieldCallback. Unless the iteration is aborted by the Heap Visit Control Flags returned by a callback, all objects in the heap are visited. Whether a callback is provided or is NULL only determines whether the callback will be invoked, it does not influence which objects are visited nor does it influence whether other callbacks will be invoked. The heap filter flags and klass provided as parameters to this function do not control which objects are visited but they do control which objects and primitive values are reported by the callbacks. For example, if the only callback that was set is array_primitive_value_callback and klass is set to the array of bytes class, then only arrays of byte will be reported. The table below summarizes this (contrast this with FollowReferences): During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
116
1.1
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description heap_filter jint This bit vector of heap filter flags. restricts the objects for which the callback function is called. This applies to both the object and primitive callbacks. klass jclass Callbacks are only reported when the object is an instance of this class. Objects which are instances of a subclass of klass are not reported. If klass is an interface, no objects are reported. This applies to both the object and primitive callbacks. If klass is NULL, callbacks are not limited to instances of a particular class. callbacks const jvmtiHeapCallbacks * Structure defining the set callback functions. Agent passes in a pointer to jvmtiHeapCallbacks. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Get Tag
jvmtiError
GetTag(jvmtiEnv* env,
jobject object,
jlong* tag_ptr)
Retrieve the tag associated with an object. The tag is a long value typically used to store a unique identifier or pointer to object information. The tag is set with SetTag. Objects for which no tags have been set return a tag value of zero.
may only be called during the start or the live phase
No
106
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description object jobject The object whose tag is to be retrieved. tag_ptr jlong* On return, the referenced long is set to the value of the tag. Agent passes a pointer to a jlong. On return, the jlong has been set. Set Tag
jvmtiError
SetTag(jvmtiEnv* env,
jobject object,
jlong tag)
Set the tag associated with an object. The tag is a long value typically used to store a unique identifier or pointer to object information. The tag is visible with GetTag.
may only be called during the start or the live phase
No
107
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description object jobject The object whose tag is to be set. tag jlong The new value of the tag. Get Objects With Tags
jvmtiError
GetObjectsWithTags(jvmtiEnv* env,
jint tag_count,
const jlong* tags,
jint* count_ptr,
jobject** object_result_ptr,
jlong** tag_result_ptr)
Return objects in the heap with the specified tags. The format is parallel arrays of objects and tags.
may only be called during the live phase
No
114
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description tag_count jint Number of tags to scan for. tags const jlong * Scan for objects with these tags. Zero is not permitted in this array. Agent passes in an array of tag_count elements of jlong. count_ptr jint * Return the number of objects with any of the tags in tags. Agent passes a pointer to a jint. On return, the jint has been set. object_result_ptr jobject ** Returns the array of objects with any of the tags in tags. Agent passes a pointer to a jobject*. On return, the jobject* points to a newly allocated array of size *count_ptr. The array should be freed with Deallocate. If object_result_ptr is NULL, this information is not returned. The objects returned by object_result_ptr are JNI local references and must be managed. tag_result_ptr jlong ** For each object in object_result_ptr, return the tag at the corresponding index. Agent passes a pointer to a jlong*. On return, the jlong* points to a newly allocated array of size *count_ptr. The array should be freed with Deallocate. If tag_result_ptr is NULL, this information is not returned. Force Garbage Collection
Force the VM to perform a garbage collection. The garbage collection is as complete as possible. This function does not cause finalizers to be run. This function does not return until the garbage collection is finished. Although garbage collection is as complete as possible there is no guarantee that alljvmtiError ForceGarbageCollection(jvmtiEnv* env)
ObjectFree events will have been sent by the time that this function returns. In particular, an object may be prevented from being freed because it is awaiting finalization.
may only be called during the live phase
No
108
1.0
Capabilities
Required Functionality
Heap (1.0) Heap (1.0) functions:jvmtiHeapObjectFilter - Heap Object Filter EnumerationjvmtiHeapRootKind - Heap Root Kind EnumerationjvmtiObjectReferenceKind - Object Reference EnumerationjvmtiIterationControl - Iteration Control EnumerationHeap Object Filter Enumeration (jvmtiHeapObjectFilter) Constant Value DescriptionJVMTI_HEAP_OBJECT_TAGGED1 Tagged objects only.JVMTI_HEAP_OBJECT_UNTAGGED2 Untagged objects only.JVMTI_HEAP_OBJECT_EITHER3 Either tagged or untagged objects.
Heap Root Kind Enumeration (jvmtiHeapRootKind) Constant Value DescriptionJVMTI_HEAP_ROOT_JNI_GLOBAL1 JNI global reference.JVMTI_HEAP_ROOT_SYSTEM_CLASS2 System class.JVMTI_HEAP_ROOT_MONITOR3 Monitor.JVMTI_HEAP_ROOT_STACK_LOCAL4 Stack local.JVMTI_HEAP_ROOT_JNI_LOCAL5 JNI local reference.JVMTI_HEAP_ROOT_THREAD6 Thread.JVMTI_HEAP_ROOT_OTHER7 Other.
Object Reference Enumeration (jvmtiObjectReferenceKind) Constant Value DescriptionJVMTI_REFERENCE_CLASS1 Reference from an object to its class.JVMTI_REFERENCE_FIELD2 Reference from an object to the value of one of its instance fields. For references of this kind thereferrer_indexparameter to the jvmtiObjectReferenceCallback is the index of the the instance field. The index is based on the order of all the object's fields. This includes all fields of the directly declared static and instance fields in the class, and includes all fields (both public and private) fields declared in superclasses and superinterfaces. The index is thus calculated by summing the index of the field in the directly declared class (seeGetClassFields), with the total number of fields (both public and private) declared in all superclasses and superinterfaces. The index starts at zero.JVMTI_REFERENCE_ARRAY_ELEMENT3 Reference from an array to one of its elements. For references of this kind thereferrer_indexparameter to the jvmtiObjectReferenceCallback is the array index.JVMTI_REFERENCE_CLASS_LOADER4 Reference from a class to its class loader.JVMTI_REFERENCE_SIGNERS5 Reference from a class to its signers array.JVMTI_REFERENCE_PROTECTION_DOMAIN6 Reference from a class to its protection domain.JVMTI_REFERENCE_INTERFACE7 Reference from a class to one of its interfaces.JVMTI_REFERENCE_STATIC_FIELD8 Reference from a class to the value of one of its static fields. For references of this kind thereferrer_indexparameter to the jvmtiObjectReferenceCallback is the index of the the static field. The index is based on the order of all the object's fields. This includes all fields of the directly declared static and instance fields in the class, and includes all fields (both public and private) fields declared in superclasses and superinterfaces. The index is thus calculated by summing the index of the field in the directly declared class (seeGetClassFields), with the total number of fields (both public and private) declared in all superclasses and superinterfaces. The index starts at zero. Note: this definition differs from that in the JVM TI 1.0 Specification.Rationale: No known implementations used the 1.0 definition.
JVMTI_REFERENCE_CONSTANT_POOL9 Reference from a class to a resolved entry in the constant pool. For references of this kind thereferrer_indexparameter to the jvmtiObjectReferenceCallback is the index into constant pool table of the class, starting at 1. See The Java™ Virtual Machine Specification, Chapter 4.4.
Iteration Control Enumeration (Heap Object CallbackjvmtiIterationControl) Constant Value DescriptionJVMTI_ITERATION_CONTINUE1 Continue the iteration. If this is a reference iteration, follow the references of this object.JVMTI_ITERATION_IGNORE2 Continue the iteration. If this is a reference iteration, ignore the references of this object.JVMTI_ITERATION_ABORT0 Abort the iteration.
typedef jvmtiIterationControl (JNICALL *jvmtiHeapObjectCallback)
(jlong class_tag,
jlong size,
jlong* tag_ptr,
void* user_data);
Agent supplied callback function. Describes (but does not pass in) an object in the heap.
Return value should be
JVMTI_ITERATION_CONTINUE
to continue iteration, or
JVMTI_ITERATION_ABORT
to stop iteration.
See the
heap callback function restrictions.
Parameters Name Type Descriptionclass_tag jlong The tag of the class of object (zero if the class is not tagged). If the object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the object (in bytes). See GetObjectSize. tag_ptr jlong* The object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. user_data void* The user supplied data that was passed into the iteration function. Heap Root Object Callback
typedef jvmtiIterationControl (JNICALL *jvmtiHeapRootCallback)
(jvmtiHeapRootKind root_kind,
jlong class_tag,
jlong size,
jlong* tag_ptr,
void* user_data);
Agent supplied callback function. Describes (but does not pass in) an object that is a root for the purposes of garbage collection.
Return value should be
JVMTI_ITERATION_CONTINUE
to continue iteration,
JVMTI_ITERATION_IGNORE
to continue iteration without pursuing references from referree object or
JVMTI_ITERATION_ABORT
to stop iteration.
See the
heap callback function restrictions.
Parameters Name Type Descriptionroot_kind jvmtiHeapRootKind The kind of heap root. class_tag jlong The tag of the class of object (zero if the class is not tagged). If the object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the object (in bytes). See GetObjectSize. tag_ptr jlong* The object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. user_data void* The user supplied data that was passed into the iteration function. Stack Reference Object Callback
typedef jvmtiIterationControl (JNICALL *jvmtiStackReferenceCallback)
(jvmtiHeapRootKind root_kind,
jlong class_tag,
jlong size,
jlong* tag_ptr,
jlong thread_tag,
jint depth,
jmethodID method,
jint slot,
void* user_data);
Agent supplied callback function. Describes (but does not pass in) an object on the stack that is a root for the purposes of garbage collection.
Return value should be
JVMTI_ITERATION_CONTINUE
to continue iteration,
JVMTI_ITERATION_IGNORE
to continue iteration without pursuing references from referree object or
JVMTI_ITERATION_ABORT
to stop iteration.
See the
heap callback function restrictions.
Parameters Name Type Descriptionroot_kind jvmtiHeapRootKind The kind of root (either JVMTI_HEAP_ROOT_STACK_LOCAL or JVMTI_HEAP_ROOT_JNI_LOCAL). class_tag jlong The tag of the class of object (zero if the class is not tagged). If the object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the object (in bytes). See GetObjectSize. tag_ptr jlong* The object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. thread_tag jlong The tag of the thread corresponding to this stack, zero if not tagged. depth jint The depth of the frame. method jmethodID The method executing in this frame. slot jint The slot number. user_data void* The user supplied data that was passed into the iteration function. Object Reference Callback
typedef jvmtiIterationControl (JNICALL *jvmtiObjectReferenceCallback)
(jvmtiObjectReferenceKind reference_kind,
jlong class_tag,
jlong size,
jlong* tag_ptr,
jlong referrer_tag,
jint referrer_index,
void* user_data);
Agent supplied callback function. Describes a reference from an object (the referrer) to another object (the referree).
Return value should be
JVMTI_ITERATION_CONTINUE
to continue iteration,
JVMTI_ITERATION_IGNORE
to continue iteration without pursuing references from referree object or
JVMTI_ITERATION_ABORT
to stop iteration.
See the
heap callback function restrictions.
Parameters Name Type Descriptionreference_kind jvmtiObjectReferenceKind The type of reference. class_tag jlong The tag of the class of referree object (zero if the class is not tagged). If the referree object represents a runtime class, the class_tag is the tag associated with java.lang.Class (zero if java.lang.Class is not tagged). size jlong Size of the referree object (in bytes). See GetObjectSize. tag_ptr jlong* The referree object tag value, or zero if the object is not tagged. To set the tag value to be associated with the object the agent sets the jlong pointed to by the parameter. referrer_tag jlong The tag of the referrer object, or zero if the referrer object is not tagged. referrer_index jint For references of type JVMTI_REFERENCE_FIELD or JVMTI_REFERENCE_STATIC_FIELD the index of the field in the referrer object. The index is based on the order of all the object's fields - see JVMTI_REFERENCE_FIELD or JVMTI_REFERENCE_STATIC_FIELD for further description. For references of type JVMTI_REFERENCE_ARRAY_ELEMENT the array index - see JVMTI_REFERENCE_ARRAY_ELEMENT for further description. For references of type JVMTI_REFERENCE_CONSTANT_POOL the index into the constant pool of the class - see JVMTI_REFERENCE_CONSTANT_POOL for further description. For references of other kinds the referrer_index is -1. user_data void* The user supplied data that was passed into the iteration function. Iterate Over Objects Reachable From Object
jvmtiError
IterateOverObjectsReachableFromObject(jvmtiEnv* env,
jobject object,
jvmtiObjectReferenceCallback object_reference_callback,
const void* user_data)
This function iterates over all objects that are directly and indirectly reachable from the specified object. For each object A (known as the referrer) with a reference to object B the specified callback function is called to describe the object reference. The callback is called exactly once for each reference from a referrer; this is true even if there are reference cycles or multiple paths to the referrer. There may be more than one reference between a referrer and a referree, These may be distinguished by the jvmtiObjectReferenceCallback.reference_kind and jvmtiObjectReferenceCallback.referrer_index. The callback for an object will always occur after the callback for its referrer. See FollowReferences for the object references which are reported. During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
109
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description object jobject The object object_reference_callback jvmtiObjectReferenceCallback The callback to be called to describe each object reference. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Iterate Over Reachable Objects
jvmtiError
IterateOverReachableObjects(jvmtiEnv* env,
jvmtiHeapRootCallback heap_root_callback,
jvmtiStackReferenceCallback stack_ref_callback,
jvmtiObjectReferenceCallback object_ref_callback,
const void* user_data)
This function iterates over the root objects and all objects that are directly and indirectly reachable from the root objects. The root objects comprise the set of system classes, JNI globals, references from thread stacks, and other objects used as roots for the purposes of garbage collection. For each root the heap_root_callback or stack_ref_callback callback is called. An object can be a root object for more than one reason and in that case the appropriate callback is called for each reason. For each object reference the object_ref_callback callback function is called to describe the object reference. The callback is called exactly once for each reference from a referrer; this is true even if there are reference cycles or multiple paths to the referrer. There may be more than one reference between a referrer and a referree, These may be distinguished by the jvmtiObjectReferenceCallback.reference_kind and jvmtiObjectReferenceCallback.referrer_index. The callback for an object will always occur after the callback for its referrer. See FollowReferences for the object references which are reported. Roots are always reported to the profiler before any object references are reported. In other words, the object_ref_callback callback will not be called until the appropriate callback has been called for all roots. If the object_ref_callback callback is specified as NULL then this function returns after reporting the root objects to the profiler. During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
110
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description heap_root_callback jvmtiHeapRootCallback The callback function to be called for each heap root of type JVMTI_HEAP_ROOT_JNI_GLOBAL, JVMTI_HEAP_ROOT_SYSTEM_CLASS, JVMTI_HEAP_ROOT_MONITOR, JVMTI_HEAP_ROOT_THREAD, or JVMTI_HEAP_ROOT_OTHER. If heap_root_callback is NULL, do not report heap roots. stack_ref_callback jvmtiStackReferenceCallback The callback function to be called for each heap root of JVMTI_HEAP_ROOT_STACK_LOCAL or JVMTI_HEAP_ROOT_JNI_LOCAL. If stack_ref_callback is NULL, do not report stack references. object_ref_callback jvmtiObjectReferenceCallback The callback function to be called for each object reference. If object_ref_callback is NULL, do not follow references from the root objects. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Iterate Over Heap
jvmtiError
IterateOverHeap(jvmtiEnv* env,
jvmtiHeapObjectFilter object_filter,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data)
Iterate over all objects in the heap. This includes both reachable and unreachable objects. The object_filter parameter indicates the objects for which the callback function is called. If this parameter is JVMTI_HEAP_OBJECT_TAGGED then the callback will only be called for every object that is tagged. If the parameter is JVMTI_HEAP_OBJECT_UNTAGGED then the callback will only be for objects that are not tagged. If the parameter is JVMTI_HEAP_OBJECT_EITHER then the callback will be called for every object in the heap, irrespective of whether it is tagged or not. During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
111
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description object_filter jvmtiHeapObjectFilter Indicates the objects for which the callback function is called. heap_object_callback jvmtiHeapObjectCallback The iterator function to be called for each object matching the object_filter. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Iterate Over Instances Of Class
jvmtiError
IterateOverInstancesOfClass(jvmtiEnv* env,
jclass klass,
jvmtiHeapObjectFilter object_filter,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data)
Iterate over all objects in the heap that are instances of the specified class. This includes direct instances of the specified class and instances of all subclasses of the specified class. This includes both reachable and unreachable objects. The object_filter parameter indicates the objects for which the callback function is called. If this parameter is JVMTI_HEAP_OBJECT_TAGGED then the callback will only be called for every object that is tagged. If the parameter is JVMTI_HEAP_OBJECT_UNTAGGED then the callback will only be called for objects that are not tagged. If the parameter is JVMTI_HEAP_OBJECT_EITHER then the callback will be called for every object in the heap, irrespective of whether it is tagged or not. During the execution of this function the state of the heap does not change: no objects are allocated, no objects are garbage collected, and the state of objects (including held values) does not change. As a result, threads executing Java programming language code, threads attempting to resume the execution of Java programming language code, and threads attempting to execute JNI functions are typically stalled.
may only be called during the live phase
No
112
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_tag_objects Can set and get tags, as described in the Heap category. Parameters Name Type Description klass jclass Iterate over objects of this class only. object_filter jvmtiHeapObjectFilter Indicates the objects for which the callback function is called. heap_object_callback jvmtiHeapObjectCallback The iterator function to be called for each klass instance matching the object_filter. user_data const void * User supplied data to be passed to the callback. Agent passes in a pointer. If user_data is NULL, NULL is passed as the user supplied data. Local Variable Local Variable functions:
GetLocalVariableTable. The GetLocalXXX functions may be used to retrieve the value of a local variable contained in the frame of a virtual thread. The SetLocalXXX functions may be used to set the value of a local variable in the topmost frame of a virtual thread suspended at a breakpoint or single step event. An implementation may support setting locals in other cases. Get Local Variable - Object
jvmtiError
GetLocalObject(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jobject* value_ptr)
This function can be used to retrieve the value of a local variable whose type is Object or a subclass of Object.
may only be called during the live phase
No
21
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value_ptr jobject* On return, points to the variable's value. Agent passes a pointer to a jobject. On return, the jobject has been set. The object returned by value_ptr is a JNI local reference and must be managed. Get Local Instance
jvmtiError
GetLocalInstance(jvmtiEnv* env,
jthread thread,
jint depth,
jobject* value_ptr)
This function can be used to retrieve the value of the local object variable at slot 0 (the "this" object) from non-static frames. This function can retrieve the "this" object from native method frames, whereas GetLocalObject() would return JVMTI_ERROR_OPAQUE_FRAME in those cases.
may only be called during the live phase
No
155
1.2
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. value_ptr jobject* On return, points to the variable's value. Agent passes a pointer to a jobject. On return, the jobject has been set. The object returned by value_ptr is a JNI local reference and must be managed. Get Local Variable - Int
jvmtiError
GetLocalInt(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jint* value_ptr)
This function can be used to retrieve the value of a local variable whose type is int, short, char, byte, or boolean.
may only be called during the live phase
No
22
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value_ptr jint* On return, points to the variable's value. Agent passes a pointer to a jint. On return, the jint has been set. Get Local Variable - Long
jvmtiError
GetLocalLong(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jlong* value_ptr)
This function can be used to retrieve the value of a local variable whose type is long.
may only be called during the live phase
No
23
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value_ptr jlong* On return, points to the variable's value. Agent passes a pointer to a jlong. On return, the jlong has been set. Get Local Variable - Float
jvmtiError
GetLocalFloat(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jfloat* value_ptr)
This function can be used to retrieve the value of a local variable whose type is float.
may only be called during the live phase
No
24
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value_ptr jfloat* On return, points to the variable's value. Agent passes a pointer to a jfloat. On return, the jfloat has been set. Get Local Variable - Double
jvmtiError
GetLocalDouble(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jdouble* value_ptr)
This function can be used to retrieve the value of a local variable whose type is long.
may only be called during the live phase
No
25
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value_ptr jdouble* On return, points to the variable's value. Agent passes a pointer to a jdouble. On return, the jdouble has been set. Set Local Variable - Object
jvmtiError
SetLocalObject(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jobject value)
This function can be used to set the value of a local variable whose type is Object or a subclass of Object.
may only be called during the live phase
No
26
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value jobject The new value for the variable. Set Local Variable - Int
jvmtiError
SetLocalInt(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jint value)
This function can be used to set the value of a local variable whose type is int, short, char, byte, or boolean.
may only be called during the live phase
No
27
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value jint The new value for the variable. Set Local Variable - Long
jvmtiError
SetLocalLong(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jlong value)
This function can be used to set the value of a local variable whose type is long.
may only be called during the live phase
No
28
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value jlong The new value for the variable. Set Local Variable - Float
jvmtiError
SetLocalFloat(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jfloat value)
This function can be used to set the value of a local variable whose type is float.
may only be called during the live phase
No
29
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value jfloat The new value for the variable. Set Local Variable - Double
jvmtiError
SetLocalDouble(jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jdouble value)
This function can be used to set the value of a local variable whose type is double.
may only be called during the live phase
No
30
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables Parameters Name Type Description thread jthread The thread of the frame containing the variable's value. If thread is NULL, the current thread is used. depth jint The depth of the frame containing the variable's value. slot jint The variable's slot number. value jdouble The new value for the variable. Breakpoint Breakpoint functions:
Set Breakpoint
jvmtiError
SetBreakpoint(jvmtiEnv* env,
jmethodID method,
jlocation location)
Set a breakpoint at the instruction indicated by method and location. An instruction can only have one breakpoint. Whenever the designated instruction is about to be executed, a Breakpoint event is generated.
may only be called during the live phase
No
38
1.0
Parameters Name Type Descriptionmethod jmethodID The method in which to set the breakpoint location jlocation the index of the instruction at which to set the breakpoint Clear Breakpoint
jvmtiError
ClearBreakpoint(jvmtiEnv* env,
jmethodID method,
jlocation location)
Clear the breakpoint at the bytecode indicated by method and location.
may only be called during the live phase
No
39
1.0
Parameters Name Type Descriptionmethod jmethodID The method in which to clear the breakpoint location jlocation the index of the instruction at which to clear the breakpoint Watched Field Watched Field functions:
jvmtiError
SetFieldAccessWatch(jvmtiEnv* env,
jclass klass,
jfieldID field)
Generate a FieldAccess event when the field specified by klass and field is about to be accessed. An event will be generated for each access of the field until it is canceled with ClearFieldAccessWatch. Field accesses from Java programming language code or from JNI code are watched, fields modified by other means are not watched. Note that JVM TI users should be aware that their own field accesses will trigger the watch. A field can only have one field access watch set. Modification of a field is not considered an access--use SetFieldModificationWatch to monitor modifications.
may only be called during the live phase
No
41
1.0
Parameters Name Type Descriptionklass jclass The class containing the field to watch field jfieldID The field to watch Clear Field Access Watch
jvmtiError
ClearFieldAccessWatch(jvmtiEnv* env,
jclass klass,
jfieldID field)
Cancel a field access watch previously set by SetFieldAccessWatch, on the field specified by klass and field.
may only be called during the live phase
No
42
1.0
Parameters Name Type Descriptionklass jclass The class containing the field to watch field jfieldID The field to watch Set Field Modification Watch
jvmtiError
SetFieldModificationWatch(jvmtiEnv* env,
jclass klass,
jfieldID field)
Generate a FieldModification event when the field specified by klass and field is about to be modified. An event will be generated for each modification of the field until it is canceled with ClearFieldModificationWatch. Field modifications from Java programming language code or from JNI code are watched, fields modified by other means are not watched. Note that JVM TI users should be aware that their own field modifications will trigger the watch. A field can only have one field modification watch set.
may only be called during the live phase
No
43
1.0
Parameters Name Type Descriptionklass jclass The class containing the field to watch field jfieldID The field to watch Clear Field Modification Watch
jvmtiError
ClearFieldModificationWatch(jvmtiEnv* env,
jclass klass,
jfieldID field)
Cancel a field modification watch previously set by SetFieldModificationWatch, on the field specified by klass and field.
may only be called during the live phase
No
44
1.0
Parameters Name Type Descriptionklass jclass The class containing the field to watch field jfieldID The field to watch Module Module functions:
jvmtiError
GetAllModules(jvmtiEnv* env,
jint* module_count_ptr,
jobject** modules_ptr)
Return an array of all modules loaded in the virtual machine. The array includes the unnamed module for each class loader. The number of modules in the array is returned via module_count_ptr, and the array itself via modules_ptr.
may only be called during the live phase
No
3
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule_count_ptr jint* On return, points to the number of returned modules. Agent passes a pointer to a jint. On return, the jint has been set. modules_ptr jobject** On return, points to an array of references, one for each module. Agent passes a pointer to a jobject*. On return, the jobject* points to a newly allocated array of size *module_count_ptr. The array should be freed with Deallocate. The objects returned by modules_ptr are JNI local references and must be managed. Get Named Module
jvmtiError
GetNamedModule(jvmtiEnv* env,
jobject class_loader,
const char* package_name,
jobject* module_ptr)
Return the java.lang.Module object for a named module defined to a class loader that contains a given package. The module is returned via module_ptr. If a named module is defined to the class loader and it contains the package then that named module is returned, otherwise NULL is returned.
may only be called during the live phase
No
40
9
Capabilities
Required Functionality
Parameters Name Type Descriptionclass_loader jobject A class loader. If the class_loader is not NULL or a subclass of java.lang.ClassLoader this function returns JVMTI_ERROR_ILLEGAL_ARGUMENT. If class_loader is NULL, the bootstrap loader is assumed. package_name const char* The name of the package, encoded as a modified UTF-8 string. The package name is in internal form (JVMS 4.2.1); identifiers are separated by forward slashes rather than periods. Agent passes in an array of char. module_ptr jobject* On return, points to a java.lang.Module object or points to NULL. Agent passes a pointer to a jobject. On return, the jobject has been set. The object returned by module_ptr is a JNI local reference and must be managed. Add Module Reads
jvmtiError
AddModuleReads(jvmtiEnv* env,
jobject module,
jobject to_module)
Update a module to read another module. This function is a no-op when module is an unnamed module. This function facilitates the instrumentation of code in named modules where that instrumentation requires expanding the set of modules that a module reads.
may only be called during the live phase
No
94
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to update. to_module jobject The additional module to read. Add Module Exports
jvmtiError
AddModuleExports(jvmtiEnv* env,
jobject module,
const char* pkg_name,
jobject to_module)
Update a module to export a package to another module. This function is a no-op when module is an unnamed module or an open module. This function facilitates the instrumentation of code in named modules where that instrumentation requires expanding the set of packages that a module exports.
may only be called during the live phase
No
95
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to update. pkg_name const char* The exported package name. Agent passes in an array of char. to_module jobject The module the package is exported to. If the to_module is not a subclass of java.lang.Module this function returns JVMTI_ERROR_INVALID_MODULE. Add Module Opens
jvmtiError
AddModuleOpens(jvmtiEnv* env,
jobject module,
const char* pkg_name,
jobject to_module)
Update a module to open a package to another module. This function is a no-op when module is an unnamed module or an open module. This function facilitates the instrumentation of code in modules where that instrumentation requires expanding the set of packages that a module opens to other modules.
may only be called during the live phase
No
96
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to update. pkg_name const char* The package name of the package to open. Agent passes in an array of char. to_module jobject The module with the package to open. If the to_module is not a subclass of java.lang.Module this function returns JVMTI_ERROR_INVALID_MODULE. Add Module Uses
jvmtiError
AddModuleUses(jvmtiEnv* env,
jobject module,
jclass service)
Updates a module to add a service to the set of services that a module uses. This function is a no-op when the module is an unnamed module. This function facilitates the instrumentation of code in named modules where that instrumentation requires expanding the set of services that a module is using.
may only be called during the live phase
No
97
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to update. service jclass The service to use. Add Module Provides
jvmtiError
AddModuleProvides(jvmtiEnv* env,
jobject module,
jclass service,
jclass impl_class)
Updates a module to add a service to the set of services that a module provides. This function is a no-op when the module is an unnamed module. This function facilitates the instrumentation of code in named modules where that instrumentation requires changes to the services that are provided.
may only be called during the live phase
No
98
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to update. service jclass The service to provide. impl_class jclass The implementation class for the provided service. Is Modifiable Module
jvmtiError
IsModifiableModule(jvmtiEnv* env,
jobject module,
jboolean* is_modifiable_module_ptr)
Determines whether a module is modifiable. If a module is modifiable then this module can be updated with AddModuleReads, AddModuleExports, AddModuleOpens, AddModuleUses, and AddModuleProvides. If a module is not modifiable then the module can not be updated with these functions. The result of this function is always JNI_TRUE when called to determine if an unnamed module is modifiable.
may only be called during the live phase
No
99
9
Capabilities
Required Functionality
Parameters Name Type Descriptionmodule jobject The module to query. is_modifiable_module_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Class Class functions:
jvmtiClassDefinition - Class redefinition description
jvmtiError
GetLoadedClasses(jvmtiEnv* env,
jint* class_count_ptr,
jclass** classes_ptr)
Return an array of all classes loaded in the virtual machine. The number of classes in the array is returned via class_count_ptr, and the array itself via classes_ptr. A class or interface creation can be triggered by one of the following:
class file representation using a class loader (see The Java™ Virtual Machine Specification, Chapter 5.3).class file representation.java.lang.Integer.TYPE) are not included in the returned list.
may only be called during the live phase
No
78
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionclass_count_ptr jint* On return, points to the number of classes. Agent passes a pointer to a jint. On return, the jint has been set. classes_ptr jclass** On return, points to an array of references, one for each class. Agent passes a pointer to a jclass*. On return, the jclass* points to a newly allocated array of size *class_count_ptr. The array should be freed with Deallocate. The objects returned by classes_ptr are JNI local references and must be managed. Get Classloader Classes
jvmtiError
GetClassLoaderClasses(jvmtiEnv* env,
jobject initiating_loader,
jint* class_count_ptr,
jclass** classes_ptr)
Returns an array of all classes which this class loader can find by name via ClassLoader::loadClass, Class::forName and bytecode linkage. That is, all classes for which initiating_loader has been recorded as an initiating loader. Each class in the returned array was created by this class loader, either by defining it directly or by delegation to another class loader. See The Java™ Virtual Machine Specification, Chapter 5.3. The returned list does not include hidden classes or interfaces or array classes whose element type is a hidden class or interface as they cannot be discovered by any class loader. The number of classes in the array is returned via class_count_ptr, and the array itself via classes_ptr. See Lookup::defineHiddenClass.
may only be called during the live phase
No
79
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioninitiating_loader jobject An initiating class loader. If initiating_loader is NULL, the classes initiated by the bootstrap loader will be returned. class_count_ptr jint* On return, points to the number of classes. Agent passes a pointer to a jint. On return, the jint has been set. classes_ptr jclass** On return, points to an array of references, one for each class. Agent passes a pointer to a jclass*. On return, the jclass* points to a newly allocated array of size *class_count_ptr. The array should be freed with Deallocate. The objects returned by classes_ptr are JNI local references and must be managed. Get Class Signature
jvmtiError
GetClassSignature(jvmtiEnv* env,
jclass klass,
char** signature_ptr,
char** generic_ptr)
Return the name and the generic signature of the class indicated by klass. If the class is a class or interface, then:
"L" + N + "." + S + ";" where N is the binary name encoded in internal form (JVMS 4.2.1) indicated by the class file passed to Lookup::defineHiddenClass, and S is an unqualified name. The returned name is not a type descriptor and does not conform to JVMS 4.3.2. For example, com.foo.Foo/AnySuffix is "Lcom/foo/Foo.AnySuffix;"klass represents an array class, then the returned name is a string consisting of one or more "[" characters representing the depth of the array nesting, followed by the class signature of the element type. For example the class signature of java.lang.String[] is "[Ljava/lang/String;" and that of int[] is "[I". If the class indicated by klass represents primitive type or void, then the returned name is the type signature character of the corresponding primitive type. For example, java.lang.Integer.TYPE is "I".
may only be called during the start or the live phase
No
48
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. signature_ptr char ** On return, points to the JNI type signature of the class, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If signature_ptr is NULL, the signature is not returned. generic_ptr char ** On return, points to the generic signature of the class, encoded as a modified UTF-8 string. If there is no generic signature attribute for the class, then, on return, points to NULL. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If generic_ptr is NULL, the generic signature is not returned. Get Class Status
jvmtiError
GetClassStatus(jvmtiEnv* env,
jclass klass,
jint* status_ptr)
Get the status of the class. Zero or more of the following bits can be set.
Class Status Flags Constant Value DescriptionJVMTI_CLASS_STATUS_VERIFIED1 Class bytecodes have been verifiedJVMTI_CLASS_STATUS_PREPARED2 Class preparation is completeJVMTI_CLASS_STATUS_INITIALIZED4 Class initialization is complete. Static initializer has been run.JVMTI_CLASS_STATUS_ERROR8 Error during initialization makes class unusableJVMTI_CLASS_STATUS_ARRAY16 Class is an array. If set, all other bits are zero.JVMTI_CLASS_STATUS_PRIMITIVE32 Class is a primitive class (for example,java.lang.Integer.TYPE). If set, all other bits are zero.
may only be called during the start or the live phase
No
49
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. status_ptr jint* On return, points to the current state of this class as one or more of the class status flags. Agent passes a pointer to a jint. On return, the jint has been set. Get Source File Name
jvmtiError
GetSourceFileName(jvmtiEnv* env,
jclass klass,
char** source_name_ptr)
For the class indicated by klass, return the source file name via source_name_ptr. The returned string is a file name only and never contains a directory name. For primitive classes (for example, java.lang.Integer.TYPE) and for arrays this function returns JVMTI_ERROR_ABSENT_INFORMATION.
may only be called during the start or the live phase
No
50
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_source_file_name Can get the source file name of a class Parameters Name Type Description klass jclass The class to query. source_name_ptr char** On return, points to the class's source file name, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. Get Class Modifiers
jvmtiError
GetClassModifiers(jvmtiEnv* env,
jclass klass,
jint* modifiers_ptr)
For the class indicated by klass, return the access flags via modifiers_ptr. Access flags are defined in The Java™ Virtual Machine Specification, Chapter 4. If the class is an array class, then its public, private, and protected modifiers are the same as those of its component type. For arrays of primitives, this component type is represented by one of the primitive classes (for example, java.lang.Integer.TYPE). If the class is a primitive class, its public modifier is always true, and its protected and private modifiers are always false. If the class is an array class or a primitive class then its final modifier is always true and its interface modifier is always false. The values of its other modifiers are not determined by this specification.
may only be called during the start or the live phase
No
51
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. modifiers_ptr jint* On return, points to the current access flags of this class. Agent passes a pointer to a jint. On return, the jint has been set. Get Class Methods
jvmtiError
GetClassMethods(jvmtiEnv* env,
jclass klass,
jint* method_count_ptr,
jmethodID** methods_ptr)
For the class indicated by klass, return a count of methods via method_count_ptr and a list of method IDs via methods_ptr. The method list contains constructors and static initializers as well as true methods. Only directly declared methods are returned (not inherited methods). An empty method list is returned for array classes and primitive classes (for example, java.lang.Integer.TYPE).
may only be called during the start or the live phase
No
52
1.0
Parameters Name Type Descriptionklass jclass The class to query. method_count_ptr jint* On return, points to the number of methods declared in this class. Agent passes a pointer to a jint. On return, the jint has been set. methods_ptr jmethodID** On return, points to the method ID array. Agent passes a pointer to a jmethodID*. On return, the jmethodID* points to a newly allocated array of size *method_count_ptr. The array should be freed with Deallocate. Get Class Fields
jvmtiError
GetClassFields(jvmtiEnv* env,
jclass klass,
jint* field_count_ptr,
jfieldID** fields_ptr)
For the class indicated by klass, return a count of fields via field_count_ptr and a list of field IDs via fields_ptr. Only directly declared fields are returned (not inherited fields). Fields are returned in the order they occur in the class file. An empty field list is returned for array classes and primitive classes (for example, java.lang.Integer.TYPE). Use JNI to determine the length of an array.
may only be called during the start or the live phase
No
53
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. field_count_ptr jint* On return, points to the number of fields declared in this class. Agent passes a pointer to a jint. On return, the jint has been set. fields_ptr jfieldID** On return, points to the field ID array. Agent passes a pointer to a jfieldID*. On return, the jfieldID* points to a newly allocated array of size *field_count_ptr. The array should be freed with Deallocate. Get Implemented Interfaces
jvmtiError
GetImplementedInterfaces(jvmtiEnv* env,
jclass klass,
jint* interface_count_ptr,
jclass** interfaces_ptr)
Return the direct super-interfaces of this class. For a class, this function returns the interfaces declared in its implements clause. For an interface, this function returns the interfaces declared in its extends clause. An empty interface list is returned for array classes and primitive classes (for example, java.lang.Integer.TYPE).
may only be called during the start or the live phase
No
54
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. interface_count_ptr jint* On return, points to the number of interfaces. Agent passes a pointer to a jint. On return, the jint has been set. interfaces_ptr jclass** On return, points to the interface array. Agent passes a pointer to a jclass*. On return, the jclass* points to a newly allocated array of size *interface_count_ptr. The array should be freed with Deallocate. The objects returned by interfaces_ptr are JNI local references and must be managed. Get Class Version Numbers
jvmtiError
GetClassVersionNumbers(jvmtiEnv* env,
jclass klass,
jint* minor_version_ptr,
jint* major_version_ptr)
For the class indicated by klass, return the minor and major version numbers, as defined in The Java™ Virtual Machine Specification, Chapter 4.
may only be called during the start or the live phase
No
145
1.1
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. minor_version_ptr jint* On return, points to the value of the minor_version item of the Class File Format. Note: to be consistent with the Class File Format, the minor version number is the first parameter. Agent passes a pointer to a jint. On return, the jint has been set. major_version_ptr jint* On return, points to the value of the major_version item of the Class File Format. Agent passes a pointer to a jint. On return, the jint has been set. Get Constant Pool
jvmtiError
GetConstantPool(jvmtiEnv* env,
jclass klass,
jint* constant_pool_count_ptr,
jint* constant_pool_byte_count_ptr,
unsigned char** constant_pool_bytes_ptr)
For the class indicated by klass, return the raw bytes of the constant pool in the format of the constant_pool item of The Java™ Virtual Machine Specification, Chapter 4. The format of the constant pool may differ between versions of the Class File Format, so, the minor and major class version numbers should be checked for compatibility. The returned constant pool might not have the same layout or contents as the constant pool in the defining class file. The constant pool returned by GetConstantPool() may have more or fewer entries than the defining constant pool. Entries may be in a different order. The constant pool returned by GetConstantPool() will match the constant pool used by GetBytecodes(). That is, the bytecodes returned by GetBytecodes() will have constant pool indices which refer to constant pool entries returned by GetConstantPool(). Note that since RetransformClasses and RedefineClasses can change the constant pool, the constant pool returned by this function can change accordingly. Thus, the correspondence between GetConstantPool() and GetBytecodes() does not hold if there is an intervening class retransformation or redefinition. The value of a constant pool entry used by a given bytecode will match that of the defining class file (even if the indices don't match). Constant pool entries which are not used directly or indirectly by bytecodes (for example, UTF-8 strings associated with annotations) are not required to exist in the returned constant pool.
may only be called during the start or the live phase
No
146
1.1
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_constant_pool Can get the constant pool of a class - GetConstantPool Parameters Name Type Description klass jclass The class to query. constant_pool_count_ptr jint* On return, points to the number of entries in the constant pool table plus one. This corresponds to the constant_pool_count item of the Class File Format. Agent passes a pointer to a jint. On return, the jint has been set. constant_pool_byte_count_ptr jint* On return, points to the number of bytes in the returned raw constant pool. Agent passes a pointer to a jint. On return, the jint has been set. constant_pool_bytes_ptr unsigned char** On return, points to the raw constant pool, that is the bytes defined by the constant_pool item of the Class File Format Agent passes a pointer to a unsigned char*. On return, the unsigned char* points to a newly allocated array of size *constant_pool_byte_count_ptr. The array should be freed with Deallocate. Is Interface
jvmtiError
IsInterface(jvmtiEnv* env,
jclass klass,
jboolean* is_interface_ptr)
Determines whether a class object reference represents an interface. The jboolean result is JNI_TRUE if the "class" is actually an interface, JNI_FALSE otherwise.
may only be called during the start or the live phase
No
55
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. is_interface_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Is Array Class
jvmtiError
IsArrayClass(jvmtiEnv* env,
jclass klass,
jboolean* is_array_class_ptr)
Determines whether a class object reference represents an array. The jboolean result is JNI_TRUE if the class is an array, JNI_FALSE otherwise.
may only be called during the start or the live phase
No
56
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. is_array_class_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Is Modifiable Class
jvmtiError
IsModifiableClass(jvmtiEnv* env,
jclass klass,
jboolean* is_modifiable_class_ptr)
Determines whether a class is modifiable. If a class is modifiable (is_modifiable_class_ptr returns JNI_TRUE) the class can be redefined with RedefineClasses (assuming the agent possesses the can_redefine_classes capability) or retransformed with RetransformClasses (assuming the agent possesses the can_retransform_classes capability). If a class is not modifiable (is_modifiable_class_ptr returns JNI_FALSE) the class can be neither redefined nor retransformed. Primitive classes (for example, java.lang.Integer.TYPE), array classes, and some implementation defined classes are never modifiable.
may only be called during the start or the live phase
No
45
1.1
Parameters Name Type Descriptionklass jclass The class to query. is_modifiable_class_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Get Class Loader
jvmtiError
GetClassLoader(jvmtiEnv* env,
jclass klass,
jobject* classloader_ptr)
For the class indicated by klass, return via classloader_ptr a reference to the class loader for the class.
may only be called during the start or the live phase
No
57
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. classloader_ptr jobject* On return, points to the class loader that loaded this class. If the class was not created by a class loader or if the class loader is the bootstrap class loader, points to NULL. Agent passes a pointer to a jobject. On return, the jobject has been set. The object returned by classloader_ptr is a JNI local reference and must be managed. Get Source Debug Extension
jvmtiError
GetSourceDebugExtension(jvmtiEnv* env,
jclass klass,
char** source_debug_extension_ptr)
For the class indicated by klass, return the debug extension via source_debug_extension_ptr. The returned string contains exactly the debug extension information present in the class file of klass.
may only be called during the start or the live phase
No
90
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_source_debug_extension Can get the source debug extension of a class Parameters Name Type Description klass jclass The class to query. source_debug_extension_ptr char** On return, points to the class's debug extension, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. Retransform Classes
jvmtiError
RetransformClasses(jvmtiEnv* env,
jint class_count,
const jclass* classes)
This function facilitates the bytecode instrumentation of already loaded classes. To replace the class definition without reference to the existing bytecodes, as one might do when recompiling from source for fix-and-continue debugging, RedefineClasses function should be used instead. When classes are initially loaded or when they are redefined, the initial class file bytes can be transformed with the ClassFileLoadHook event. This function reruns the transformation process (whether or not a transformation has previously occurred). This retransformation follows these steps:
ClassFileLoadHook event during the previous load or redefine, the bytes it returned (via the new_class_data parameter) are reused as the output of the transformation; note that this is equivalent to reapplying the previous transformation, unaltered. except that the ClassFileLoadHook event is not sent to these agentsClassFileLoadHook event is sent, allowing a new transformation to be appliedClassFileLoadHook event for more details. The initial class file bytes represent the bytes passed to ClassLoader.defineClass or RedefineClasses (before any transformations were applied), however they may not exactly match them. The constant pool may differ in ways described in GetConstantPool. Constant pool indices in the bytecodes of methods will correspond. Some attributes may not be present. Where order is not meaningful, for example the order of methods, order may not be preserved. Retransformation can cause new versions of methods to be installed. Old method versions may become obsolete The new method version will be used on new invokes. If a method has active stack frames, those active frames continue to run the bytecodes of the original method version. This function does not cause any initialization except that which would occur under the customary JVM semantics. In other words, retransforming a class does not cause its initializers to be run. The values of static fields will remain as they were prior to the call. Threads need not be suspended. All breakpoints in the class are cleared. All attributes are updated. Instances of the retransformed class are not affected -- fields retain their previous values. Tags on the instances are also unaffected. In response to this call, no events other than the ClassFileLoadHook event will be sent. The retransformation may change method bodies, the constant pool and attributes (unless explicitly prohibited). The retransformation must not add, remove or rename fields or methods, change the signatures of methods, change modifiers, or change inheritance. The retransformation must not change the NestHost, NestMembers, Record, or PermittedSubclasses attributes. These restrictions may be lifted in future versions. See the error return description below for information on error codes returned if an unsupported retransformation is attempted. The class file bytes are not verified or installed until they have passed through the chain of ClassFileLoadHook events, thus the returned error code reflects the result of the transformations. If any error code is returned other than JVMTI_ERROR_NONE, none of the classes to be retransformed will have a new definition installed. When this function returns (with the error code of JVMTI_ERROR_NONE) all of the classes to be retransformed will have their new definitions installed.
may only be called during the live phase
No
152
1.1
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_retransform_classes Can retransform classes with RetransformClasses. In addition to the restrictions imposed by the specific implementation on this capability (see the Capability section), this capability must be set before the ClassFileLoadHook event is enabled for the first time in this environment. An environment that possesses this capability at the time that ClassFileLoadHook is enabled for the first time is said to be retransformation capable. An environment that does not possess this capability at the time that ClassFileLoadHook is enabled for the first time is said to be retransformation incapable. Optional Features can_retransform_any_class RetransformClasses can be called on any modifiable class. See IsModifiableClass. (can_retransform_classes must also be set) Parameters Name Type Description class_count jint The number of classes to be retransformed. classes const jclass* The array of classes to be retransformed. Agent passes in an array of class_count elements of jclass. Redefine Classes
All classes given are redefined according to the definitions supplied. This function is used to replace the definition of a class with a new definition, as might be needed in fix-and-continue debugging. Where the existing class file bytes are to be transformed, for example in bytecode instrumentation,typedef struct { jclass klass; jint class_byte_count; const unsigned char* class_bytes; } jvmtiClassDefinition;jvmtiError RedefineClasses(jvmtiEnv* env, jint class_count, const jvmtiClassDefinition* class_definitions)
RetransformClasses should be used. Redefinition can cause new versions of methods to be installed. Old method versions may become obsolete The new method version will be used on new invokes. If a method has active stack frames, those active frames continue to run the bytecodes of the original method version. If resetting of stack frames is desired, use PopFrame to pop frames with obsolete method versions. This function does not cause any initialization except that which would occur under the customary JVM semantics. In other words, redefining a class does not cause its initializers to be run. The values of static fields will remain as they were prior to the call. Threads need not be suspended. All breakpoints in the class are cleared. All attributes are updated. Instances of the redefined class are not affected -- fields retain their previous values. Tags on the instances are also unaffected. In response to this call, the JVM TI event Class File Load Hook will be sent (if enabled), but no other JVM TI events will be sent. The redefinition may change method bodies, the constant pool and attributes (unless explicitly prohibited). The redefinition must not add, remove or rename fields or methods, change the signatures of methods, change modifiers, or change inheritance. The redefinition must not change the NestHost, NestMembers, Record, or PermittedSubclasses attributes. These restrictions may be lifted in future versions. See the error return description below for information on error codes returned if an unsupported redefinition is attempted. The class file bytes are not verified or installed until they have passed through the chain of ClassFileLoadHook events, thus the returned error code reflects the result of the transformations applied to the bytes passed into class_definitions. If any error code is returned other than JVMTI_ERROR_NONE, none of the classes to be redefined will have a new definition installed. When this function returns (with the error code of JVMTI_ERROR_NONE) all of the classes to be redefined will have their new definitions installed.
may only be called during the live phase
No
87
1.0
jvmtiClassDefinition - Class redefinition description Field Type Description klass jclass Class object for this class class_byte_count jint Number of bytes defining class (below) class_bytes const unsigned char* Bytes defining class (in The Java™ Virtual Machine Specification, Chapter 4) Parameters Name Type Description class_count jint The number of classes specified in class_definitions class_definitions const jvmtiClassDefinition* The array of new class definitions Agent passes in an array of class_count elements of jvmtiClassDefinition. Object Object functions:
Object types:
jvmtiMonitorUsage - Object monitor usage information
jvmtiError
GetObjectSize(jvmtiEnv* env,
jobject object,
jlong* size_ptr)
For the object indicated by object, return via size_ptr the size of the object. This size is an implementation-specific approximation of the amount of storage consumed by this object. It may include some or all of the object's overhead, and thus is useful for comparison within an implementation but not between implementations. The estimate may change during a single invocation of the JVM.
may only be called during the start or the live phase
No
154
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionobject jobject The object to query. size_ptr jlong* On return, points to the object's size in bytes. Agent passes a pointer to a jlong. On return, the jlong has been set. Get Object Hash Code
jvmtiError
GetObjectHashCode(jvmtiEnv* env,
jobject object,
jint* hash_code_ptr)
For the object indicated by object, return via hash_code_ptr a hash code. This hash code could be used to maintain a hash table of object references, however, on some implementations this can cause significant performance impacts--in most cases tags will be a more efficient means of associating information with objects. This function guarantees the same hash code value for a particular object throughout its life
may only be called during the start or the live phase
No
58
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionobject jobject The object to query. hash_code_ptr jint* On return, points to the object's hash code. Agent passes a pointer to a jint. On return, the jint has been set. Get Object Monitor Usage
Get information about the object's monitor. The fields of thetypedef struct { jthread owner; jint entry_count; jint waiter_count; jthread* waiters; jint notify_waiter_count; jthread* notify_waiters; } jvmtiMonitorUsage;jvmtiError GetObjectMonitorUsage(jvmtiEnv* env, jobject object, jvmtiMonitorUsage* info_ptr)
jvmtiMonitorUsage structure are filled in with information about usage of the monitor.
may only be called during the live phase
No
59
1.0
jvmtiMonitorUsage - Object monitor usage information Field Type Description owner jthread The thread owning this monitor, or NULL if unused entry_count jint The number of times the owning thread has entered the monitor waiter_count jint The number of threads waiting to own this monitor waiters jthread* The waiter_count waiting threads notify_waiter_count jint The number of threads waiting to be notified by this monitor notify_waiters jthread* The notify_waiter_count threads waiting to be notified Parameters Name Type Description object jobject The object to query. info_ptr jvmtiMonitorUsage* On return, filled with monitor information for the specified object. Agent passes a pointer to a jvmtiMonitorUsage. On return, the jvmtiMonitorUsage has been set. The object returned in the field owner of jvmtiMonitorUsage is a JNI local reference and must be managed. The pointer returned in the field waiters of jvmtiMonitorUsage is a newly allocated array. The array should be freed with Deallocate. The objects returned in the field waiters of jvmtiMonitorUsage are JNI local references and must be managed. The pointer returned in the field notify_waiters of jvmtiMonitorUsage is a newly allocated array. The array should be freed with Deallocate. The objects returned in the field notify_waiters of jvmtiMonitorUsage are JNI local references and must be managed. Field Field functions:
Get Field Name (and Signature)
jvmtiError
GetFieldName(jvmtiEnv* env,
jclass klass,
jfieldID field,
char** name_ptr,
char** signature_ptr,
char** generic_ptr)
For the field indicated by klass and field, return the field name via name_ptr and field signature via signature_ptr. Field signatures are defined in the JNI Specification and are referred to as field descriptors in The Java™ Virtual Machine Specification, Chapter 4.3.2.
may only be called during the start or the live phase
No
60
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class of the field to query. field jfieldID The field to query. name_ptr char ** On return, points to the field name, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If name_ptr is NULL, the name is not returned. signature_ptr char ** On return, points to the field signature, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If signature_ptr is NULL, the signature is not returned. generic_ptr char ** On return, points to the generic signature of the field, encoded as a modified UTF-8 string. If there is no generic signature attribute for the field, then, on return, points to NULL. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If generic_ptr is NULL, the generic signature is not returned. Get Field Declaring Class
jvmtiError
GetFieldDeclaringClass(jvmtiEnv* env,
jclass klass,
jfieldID field,
jclass* declaring_class_ptr)
For the field indicated by klass and field return the class that defined it via declaring_class_ptr. The declaring class will either be klass, a superclass, or an implemented interface.
may only be called during the start or the live phase
No
61
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. field jfieldID The field to query. declaring_class_ptr jclass* On return, points to the declaring class Agent passes a pointer to a jclass. On return, the jclass has been set. The object returned by declaring_class_ptr is a JNI local reference and must be managed. Get Field Modifiers
jvmtiError
GetFieldModifiers(jvmtiEnv* env,
jclass klass,
jfieldID field,
jint* modifiers_ptr)
For the field indicated by klass and field return the access flags via modifiers_ptr. Access flags are defined in The Java™ Virtual Machine Specification, Chapter 4.
may only be called during the start or the live phase
No
62
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionklass jclass The class to query. field jfieldID The field to query. modifiers_ptr jint* On return, points to the access flags. Agent passes a pointer to a jint. On return, the jint has been set. Is Field Synthetic
jvmtiError
IsFieldSynthetic(jvmtiEnv* env,
jclass klass,
jfieldID field,
jboolean* is_synthetic_ptr)
For the field indicated by klass and field, return a value indicating whether the field is synthetic via is_synthetic_ptr. Synthetic fields are generated by the compiler but not present in the original source code.
may only be called during the start or the live phase
No
63
1.0
Parameters Name Type Descriptionklass jclass The class of the field to query. field jfieldID The field to query. is_synthetic_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Method Method functions:
jvmtiLineNumberEntry - Line number table entryjvmtiLocalVariableEntry - Local variable table entryjmethodID) and set how methods are processed. Obsolete Methods The functions RetransformClasses and RedefineClasses can cause new versions of methods to be installed. An original version of a method is considered equivalent to the new version if:
IsMethodObsolete. Get Method Name (and Signature)
jvmtiError
GetMethodName(jvmtiEnv* env,
jmethodID method,
char** name_ptr,
char** signature_ptr,
char** generic_ptr)
For the method indicated by method, return the method name via name_ptr and method signature via signature_ptr. Method signatures are defined in the JNI Specification and are referred to as method descriptors in The Java™ Virtual Machine Specification, Chapter 4.3.3. Note this is different than method signatures as defined in the Java Language Specification.
may only be called during the start or the live phase
No
64
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. name_ptr char ** On return, points to the method name, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If name_ptr is NULL, the name is not returned. signature_ptr char ** On return, points to the method signature, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If signature_ptr is NULL, the signature is not returned. generic_ptr char ** On return, points to the generic signature of the method, encoded as a modified UTF-8 string. If there is no generic signature attribute for the method, then, on return, points to NULL. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. If generic_ptr is NULL, the generic signature is not returned. Get Method Declaring Class
jvmtiError
GetMethodDeclaringClass(jvmtiEnv* env,
jmethodID method,
jclass* declaring_class_ptr)
For the method indicated by method, return the class that defined it via declaring_class_ptr.
may only be called during the start or the live phase
No
65
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. declaring_class_ptr jclass* On return, points to the declaring class Agent passes a pointer to a jclass. On return, the jclass has been set. The object returned by declaring_class_ptr is a JNI local reference and must be managed. Get Method Modifiers
jvmtiError
GetMethodModifiers(jvmtiEnv* env,
jmethodID method,
jint* modifiers_ptr)
For the method indicated by method, return the access flags via modifiers_ptr. Access flags are defined in The Java™ Virtual Machine Specification, Chapter 4.
may only be called during the start or the live phase
No
66
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. modifiers_ptr jint* On return, points to the access flags. Agent passes a pointer to a jint. On return, the jint has been set. Get Max Locals
jvmtiError
GetMaxLocals(jvmtiEnv* env,
jmethodID method,
jint* max_ptr)
For the method indicated by method, return the number of local variable slots used by the method, including the local variables used to pass parameters to the method on its invocation. See max_locals in The Java™ Virtual Machine Specification, Chapter 4.7.3.
may only be called during the start or the live phase
No
68
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. max_ptr jint* On return, points to the maximum number of local slots Agent passes a pointer to a jint. On return, the jint has been set. Get Arguments Size
jvmtiError
GetArgumentsSize(jvmtiEnv* env,
jmethodID method,
jint* size_ptr)
For the method indicated by method, return via max_ptr the number of local variable slots used by the method's arguments. Note that two-word arguments use two slots.
may only be called during the start or the live phase
No
69
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. size_ptr jint* On return, points to the number of argument slots Agent passes a pointer to a jint. On return, the jint has been set. Get Line Number Table
For the method indicated bytypedef struct { jlocation start_location; jint line_number; } jvmtiLineNumberEntry;jvmtiError GetLineNumberTable(jvmtiEnv* env, jmethodID method, jint* entry_count_ptr, jvmtiLineNumberEntry** table_ptr)
method, return a table of source line number entries. The size of the table is returned via entry_count_ptr and the table itself is returned via table_ptr.
may only be called during the start or the live phase
No
70
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_line_numbers Can get the line number table of a method jvmtiLineNumberEntry - Line number table entry Field Type Description start_location jlocation the jlocation where the line begins line_number jint the line number Parameters Name Type Description method jmethodID The method to query. entry_count_ptr jint* On return, points to the number of entries in the table Agent passes a pointer to a jint. On return, the jint has been set. table_ptr jvmtiLineNumberEntry** On return, points to the line number table pointer. Agent passes a pointer to a jvmtiLineNumberEntry*. On return, the jvmtiLineNumberEntry* points to a newly allocated array of size *entry_count_ptr. The array should be freed with Deallocate. Get Method Location
jvmtiError
GetMethodLocation(jvmtiEnv* env,
jmethodID method,
jlocation* start_location_ptr,
jlocation* end_location_ptr)
For the method indicated by method, return the beginning and ending addresses through start_location_ptr and end_location_ptr. In a conventional bytecode indexing scheme, start_location_ptr will always point to zero and end_location_ptr will always point to the bytecode count minus one.
may only be called during the start or the live phase
No
71
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. start_location_ptr jlocation* On return, points to the first location, or -1 if location information is not available. If the information is available and GetJLocationFormat returns JVMTI_JLOCATION_JVMBCI then this will always be zero. Agent passes a pointer to a jlocation. On return, the jlocation has been set. end_location_ptr jlocation* On return, points to the last location, or -1 if location information is not available. Agent passes a pointer to a jlocation. On return, the jlocation has been set. Get Local Variable Table
Return local variable information.typedef struct { jlocation start_location; jint length; char* name; char* signature; char* generic_signature; jint slot; } jvmtiLocalVariableEntry;jvmtiError GetLocalVariableTable(jvmtiEnv* env, jmethodID method, jint* entry_count_ptr, jvmtiLocalVariableEntry** table_ptr)
may only be called during the live phase
No
72
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_access_local_variables Can set and get local variables jvmtiLocalVariableEntry - Local variable table entry Field Type Description start_location jlocation The code array index where the local variable is first valid (that is, where it must have a value). length jint The length of the valid section for this local variable. The last code array index where the local variable is valid is start_location + length. name char* The local variable name, encoded as a modified UTF-8 string. signature char* The local variable's type signature, encoded as a modified UTF-8 string. The signature format is the same as that defined in The Java™ Virtual Machine Specification, Chapter 4.3.2. generic_signature char* The local variable's generic signature, encoded as a modified UTF-8 string. The value of this field will be NULL for any local variable which does not have a generic type. slot jint The local variable's slot. See Local Variables. Parameters Name Type Description method jmethodID The method to query. entry_count_ptr jint* On return, points to the number of entries in the table Agent passes a pointer to a jint. On return, the jint has been set. table_ptr jvmtiLocalVariableEntry** On return, points to an array of local variable table entries. Agent passes a pointer to a jvmtiLocalVariableEntry*. On return, the jvmtiLocalVariableEntry* points to a newly allocated array of size *entry_count_ptr. The array should be freed with Deallocate. The pointers returned in the field name of jvmtiLocalVariableEntry are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field signature of jvmtiLocalVariableEntry are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field generic_signature of jvmtiLocalVariableEntry are newly allocated arrays. The arrays should be freed with Deallocate. Get Bytecodes
jvmtiError
GetBytecodes(jvmtiEnv* env,
jmethodID method,
jint* bytecode_count_ptr,
unsigned char** bytecodes_ptr)
For the method indicated by method, return the bytecodes that implement the method. The number of bytecodes is returned via bytecode_count_ptr. The bytecodes themselves are returned via bytecodes_ptr.
may only be called during the start or the live phase
No
75
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_bytecodes Can get bytecodes of a method GetBytecodes Parameters Name Type Description method jmethodID The method to query. bytecode_count_ptr jint* On return, points to the length of the bytecode array Agent passes a pointer to a jint. On return, the jint has been set. bytecodes_ptr unsigned char** On return, points to the pointer to the bytecode array Agent passes a pointer to a unsigned char*. On return, the unsigned char* points to a newly allocated array of size *bytecode_count_ptr. The array should be freed with Deallocate. Is Method Native
jvmtiError
IsMethodNative(jvmtiEnv* env,
jmethodID method,
jboolean* is_native_ptr)
For the method indicated by method, return a value indicating whether the method is native via is_native_ptr
may only be called during the start or the live phase
No
76
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method to query. is_native_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Is Method Synthetic
jvmtiError
IsMethodSynthetic(jvmtiEnv* env,
jmethodID method,
jboolean* is_synthetic_ptr)
For the method indicated by method, return a value indicating whether the method is synthetic via is_synthetic_ptr. Synthetic methods are generated by the compiler but not present in the original source code.
may only be called during the start or the live phase
No
77
1.0
Parameters Name Type Descriptionmethod jmethodID The method to query. is_synthetic_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Is Method Obsolete
jvmtiError
IsMethodObsolete(jvmtiEnv* env,
jmethodID method,
jboolean* is_obsolete_ptr)
Determine if a method ID refers to an obsolete method version.
may only be called during the start or the live phase
No
91
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmethod jmethodID The method ID to query. is_obsolete_ptr jboolean* On return, points to the boolean result of this function. Agent passes a pointer to a jboolean. On return, the jboolean has been set. Set Native Method Prefix
jvmtiError
SetNativeMethodPrefix(jvmtiEnv* env,
const char* prefix)
This function modifies the failure handling of native method resolution by allowing retry with a prefix applied to the name. When used with the ClassFileLoadHook event, it enables native methods to be instrumented. Since native methods cannot be directly instrumented (they have no bytecodes), they must be wrapped with a non-native method which can be instrumented. For example, if we had:
We could transform the class file (with the ClassFileLoadHook event) so that this becomes:native boolean foo(int x);
boolean foo(int x) {
... record entry to foo ...
return wrapped_foo(x);
}
native boolean wrapped_foo(int x);
Where foo becomes a wrapper for the actual native method with the appended prefix "wrapped_". Note that "wrapped_" would be a poor choice of prefix since it might conceivably form the name of an existing method thus something like "$$$MyAgentWrapped$$$_" would be better but would make these examples less readable. The wrapper will allow data to be collected on the native method call, but now the problem becomes linking up the wrapped method with the native implementation. That is, the method wrapped_foo needs to be resolved to the native implementation of foo, which might be:
This function allows the prefix to be specified and the proper resolution to occur. Specifically, when the standard resolution fails, the resolution is retried taking the prefix into consideration. There are two ways that resolution occurs, explicit resolution with the JNI functionJava_somePackage_someClass_foo(JNIEnv* env, jint x)
RegisterNatives and the normal automatic resolution. For RegisterNatives, the VM will attempt this association:
When this fails, the resolution will be retried with the specified prefix prepended to the method name, yielding the correct resolution:method(foo) -> nativeImplementation(foo)
For automatic resolution, the VM will attempt:method(wrapped_foo) -> nativeImplementation(foo)
When this fails, the resolution will be retried with the specified prefix deleted from the implementation name, yielding the correct resolution:method(wrapped_foo) -> nativeImplementation(wrapped_foo)
Note that since the prefix is only used when standard resolution fails, native methods can be wrapped selectively. Since each JVM TI environment is independent and can do its own transformation of the bytecodes, more than one layer of wrappers may be applied. Thus each environment needs its own prefix. Since transformations are applied in order, the prefixes, if applied, will be applied in the same order. The order of transformation application is described in themethod(wrapped_foo) -> nativeImplementation(foo)
ClassFileLoadHook event. Thus if three environments applied wrappers, foo might become $env3_$env2_$env1_foo. But if, say, the second environment did not apply a wrapper to foo it would be just $env3_$env1_foo. To be able to efficiently determine the sequence of prefixes, an intermediate prefix is only applied if its non-native wrapper exists. Thus, in the last example, even though $env1_foo is not a native method, the $env1_ prefix is applied since $env1_foo exists. Since the prefixes are used at resolution time and since resolution may be arbitrarily delayed, a native method prefix must remain set as long as there are corresponding prefixed native methods.
may be called during any phase
No
73
1.1
Parameters Name Type Descriptionprefix const char * The prefix to apply, encoded as a modified UTF-8 string. Agent passes in an array of char. If prefix is NULL, any existing prefix in this environment is cancelled . Set Native Method Prefixes
jvmtiError
SetNativeMethodPrefixes(jvmtiEnv* env,
jint prefix_count,
char** prefixes)
For a normal agent, SetNativeMethodPrefix will provide all needed native method prefixing. For a meta-agent that performs multiple independent class file transformations (for example as a proxy for another layer of agents) this function allows each transformation to have its own prefix. The prefixes are applied in the order supplied and are processed in the same manner as described for the application of prefixes from multiple JVM TI environments in SetNativeMethodPrefix. Any previous prefixes are replaced. Thus, calling this function with a prefix_count of 0 disables prefixing in this environment. SetNativeMethodPrefix and this function are the two ways to set the prefixes. Calling SetNativeMethodPrefix with a prefix is the same as calling this function with prefix_count of 1. Calling SetNativeMethodPrefix with NULL is the same as calling this function with prefix_count of 0.
may be called during any phase
No
74
1.1
Parameters Name Type Descriptionprefix_count jint The number of prefixes to apply. prefixes char ** The prefixes to apply for this environment, each encoded as a modified UTF-8 string. Raw Monitor Raw Monitor functions:
jvmtiError
CreateRawMonitor(jvmtiEnv* env,
const char* name,
jrawMonitorID* monitor_ptr)
Create a raw monitor.
may only be called during the OnLoad or the live phase
31
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionname const char* A name to identify the monitor, encoded as a modified UTF-8 string. Agent passes in an array of char. monitor_ptr jrawMonitorID* On return, points to the created monitor. Agent passes a pointer to a jrawMonitorID. On return, the jrawMonitorID has been set. Destroy Raw Monitor
jvmtiError
DestroyRawMonitor(jvmtiEnv* env,
jrawMonitorID monitor)
Destroy the raw monitor. If the monitor being destroyed has been entered by this thread, it will be exited before it is destroyed. If the monitor being destroyed has been entered by another thread, an error will be returned and the monitor will not be destroyed.
may only be called during the OnLoad or the live phase
32
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor Raw Monitor Enter
jvmtiError
RawMonitorEnter(jvmtiEnv* env,
jrawMonitorID monitor)
Gain exclusive ownership of a raw monitor. The same thread may enter a monitor more then once. The thread must exit the monitor the same number of times as it is entered. If a monitor is entered during OnLoad (before attached threads exist) and has not exited when attached threads come into existence, the enter is considered to have occurred on the main thread.
may be called during any phase
33
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor Raw Monitor Exit
jvmtiError
RawMonitorExit(jvmtiEnv* env,
jrawMonitorID monitor)
Release exclusive ownership of a raw monitor.
may be called during any phase
34
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor Raw Monitor Wait
jvmtiError
RawMonitorWait(jvmtiEnv* env,
jrawMonitorID monitor,
jlong millis)
Wait for notification of the raw monitor. Causes the current thread to wait until either another thread calls RawMonitorNotify or RawMonitorNotifyAll for the specified raw monitor, or the specified timeout has elapsed.
may be called during any phase
35
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor millis jlong The timeout, in milliseconds. If the timeout is zero, then real time is not taken into consideration and the thread simply waits until notified. Raw Monitor Notify
jvmtiError
RawMonitorNotify(jvmtiEnv* env,
jrawMonitorID monitor)
Notify a single thread waiting on the raw monitor.
may be called during any phase
36
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor Raw Monitor Notify All
jvmtiError
RawMonitorNotifyAll(jvmtiEnv* env,
jrawMonitorID monitor)
Notify all threads waiting on the raw monitor.
may be called during any phase
37
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionmonitor jrawMonitorID The monitor JNI Function Interception JNI Function Interception functions:
Provides the ability to intercept and resend Java Native Interface (JNI) function calls by manipulating the JNI function table. See JNI Functions in the Java Native Interface Specification. The following example illustrates intercepting the NewGlobalRef JNI call in order to count reference creation.
JNIEnv original_jni_Functions;
JNIEnv redirected_jni_Functions;
int my_global_ref_count = 0;
jobject
MyNewGlobalRef(JNIEnv *jni_env, jobject lobj) {
++my_global_ref_count;
return originalJNIFunctions->NewGlobalRef(env, lobj);
}
void
myInit() {
jvmtiError err;
err = (*jvmti_env)->GetJNIFunctionTable(jvmti_env, &original_jni_Functions);
if (err != JVMTI_ERROR_NONE) {
die();
}
err = (*jvmti_env)->GetJNIFunctionTable(jvmti_env, &redirected_jni_Functions);
if (err != JVMTI_ERROR_NONE) {
die();
}
redirectedJNIFunctions->NewGlobalRef = MyNewGlobalRef;
err = (*jvmti_env)->SetJNIFunctionTable(jvmti_env, redirected_jni_Functions);
if (err != JVMTI_ERROR_NONE) {
die();
}
}
Sometime after myInit is called the user's JNI code is executed which makes the call to create a new global reference. Instead of going to the normal JNI implementation the call goes to myNewGlobalRef. Note that a copy of the original function table is kept so that the normal JNI function can be called after the data is collected. Note also that any JNI functions which are not overwritten will behave normally. Set JNI Function Table
jvmtiError
SetJNIFunctionTable(jvmtiEnv* env,
const jniNativeInterface* function_table)
Set the JNI function table in all current and future JNI environments. As a result, all future JNI calls are directed to the specified functions. Use GetJNIFunctionTable to get the function table to pass to this function. For this function to take effect the updated table entries must be used by the JNI clients. Since the table is defined const some compilers may optimize away the access to the table, thus preventing this function from taking effect. The table is copied--changes to the local copy of the table have no effect. This function affects only the function table, all other aspects of the environment are unaffected. See the examples above.
may only be called during the start or the live phase
No
120
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionfunction_table const jniNativeInterface * Points to the new JNI function table. Agent passes in a pointer to jniNativeInterface. Get JNI Function Table
jvmtiError
GetJNIFunctionTable(jvmtiEnv* env,
jniNativeInterface** function_table)
Get the JNI function table. The JNI function table is copied into allocated memory. If SetJNIFunctionTable has been called, the modified (not the original) function table is returned. Only the function table is copied, no other aspects of the environment are copied. See the examples above.
may only be called during the start or the live phase
No
121
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionfunction_table jniNativeInterface ** On return, *function_table points a newly allocated copy of the JNI function table. Agent passes a pointer to a jniNativeInterface*. On return, the jniNativeInterface* points to a newly allocated array. The array should be freed with Deallocate. Event Management Event Management functions:
Event Management types:
jvmtiEventMode - Event Enable/Disable
jvmtiError
SetEventCallbacks(jvmtiEnv* env,
const jvmtiEventCallbacks* callbacks,
jint size_of_callbacks)
Set the functions to be called for each event. The callbacks are specified by supplying a replacement function table. The function table is copied--changes to the local copy of the table have no effect. This is an atomic action, all callbacks are set at once. No events are sent before this function is called. When an entry is NULL or when the event is beyond size_of_callbacks no event is sent. Details on events are described later in this document. An event must be enabled and have a callback in order to be sent--the order in which this function and SetEventNotificationMode are called does not affect the result.
may only be called during the OnLoad or the live phase
No
122
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncallbacks const jvmtiEventCallbacks * The new event callbacks. Agent passes in a pointer to jvmtiEventCallbacks. If callbacks is NULL, remove the existing callbacks. size_of_callbacks jint sizeof(jvmtiEventCallbacks)--for version compatibility. Set Event Notification Mode
Control the generation of events.typedef enum { JVMTI_ENABLE = 1, JVMTI_DISABLE = 0 } jvmtiEventMode;jvmtiError SetEventNotificationMode(jvmtiEnv* env, jvmtiEventMode mode, jvmtiEvent event_type, jthread event_thread, ...)
Event Enable/Disable (IfjvmtiEventMode) Constant Value DescriptionJVMTI_ENABLE1 IfmodeisJVMTI_ENABLE, the eventevent_typewill be enabledJVMTI_DISABLE0 IfmodeisJVMTI_DISABLE, the eventevent_typewill be disabled
event_thread is NULL, the event is enabled or disabled globally; otherwise, it is enabled or disabled for a particular thread. An event is generated for a particular thread if it is enabled either at the thread or global levels. See below for information on specific events. The following events cannot be controlled at the thread level through this function.
VMInitVMStartVMDeathThreadStartCompiledMethodLoadCompiledMethodUnloadDynamicCodeGeneratedDataDumpRequestmay only be called during the OnLoad or the live phase
No
2
1.0
Parameters Name Type Descriptionmode jvmtiEventMode JVMTI_ENABLE or JVMTI_DISABLE event_type jvmtiEvent the event to control event_thread jthread The thread to control If event_thread is NULL, event is controlled at the global level. ... ... for future expansion Generate Events
jvmtiError
GenerateEvents(jvmtiEnv* env,
jvmtiEvent event_type)
Generate events to represent the current state of the VM. For example, if event_type is JVMTI_EVENT_COMPILED_METHOD_LOAD, a CompiledMethodLoad event will be sent for each currently compiled method. Methods that were loaded and now have been unloaded are not sent. The history of what events have previously been sent does not effect what events are sent by this function--for example, all currently compiled methods will be sent each time this function is called. This function is useful when events may have been missed due to the agent attaching after program execution begins; this function generates the missed events. Attempts to execute Java programming language code or JNI functions may be paused until this function returns - so neither should be called from the thread sending the event. This function returns only after the missed events have been sent, processed and have returned. The event may be sent on a different thread than the thread on which the event occurred. The callback for the event must be set with SetEventCallbacks and the event must be enabled with SetEventNotificationMode or the events will not occur. If the VM no longer has the information to generate some or all of the requested events, the events are simply not sent - no error is returned. Only the following events are supported:
may only be called during the live phase
No
123
1.0
Extension Mechanism Extension Mechanism functions: Extension Mechanism function types: Extension Mechanism types:jvmtiParamTypes - Extension Function/Event Parameter TypesjvmtiParamKind - Extension Function/Event Parameter KindsjvmtiParamInfo - Extension Function/Event Parameter InfojvmtiExtensionFunctionInfo - Extension Function InfojvmtiExtensionEventInfo - Extension Event InfoExtension Function/Event Parameter Types (jvmtiParamTypes) Constant Value DescriptionJVMTI_TYPE_JBYTE101 Java programming language primitive type -byte. JNI typejbyte.JVMTI_TYPE_JCHAR102 Java programming language primitive type -char. JNI typejchar.JVMTI_TYPE_JSHORT103 Java programming language primitive type -short. JNI typejshort.JVMTI_TYPE_JINT104 Java programming language primitive type -int. JNI typejint.JVMTI_TYPE_JLONG105 Java programming language primitive type -long. JNI typejlong.JVMTI_TYPE_JFLOAT106 Java programming language primitive type -float. JNI typejfloat.JVMTI_TYPE_JDOUBLE107 Java programming language primitive type -double. JNI typejdouble.JVMTI_TYPE_JBOOLEAN108 Java programming language primitive type -boolean. JNI typejboolean.JVMTI_TYPE_JOBJECT109 Java programming language object type -java.lang.Object. JNI typejobject. Returned values are JNI local references and must be managed.JVMTI_TYPE_JTHREAD110 Java programming language object type -java.lang.Thread. JVM TI typejthread. Returned values are JNI local references and must be managed.JVMTI_TYPE_JCLASS111 Java programming language object type -java.lang.Class. JNI typejclass. Returned values are JNI local references and must be managed.JVMTI_TYPE_JVALUE112 Union of all Java programming language primitive and object types - JNI typejvalue. Returned values which represent object types are JNI local references and must be managed.JVMTI_TYPE_JFIELDID113 Java programming language field identifier - JNI typejfieldID.JVMTI_TYPE_JMETHODID114 Java programming language method identifier - JNI typejmethodID.JVMTI_TYPE_CCHAR115 C programming language type -char.JVMTI_TYPE_CVOID116 C programming language type -void.JVMTI_TYPE_JNIENV117 JNI environment -JNIEnv. Should be used with the correctjvmtiParamKindto make it a pointer type.
Extension Function/Event Parameter Kinds (Extension Function/Event Parameter InfojvmtiParamKind) Constant Value DescriptionJVMTI_KIND_IN91 Ingoing argument -foo.JVMTI_KIND_IN_PTR92 Ingoing pointer argument -const foo*.JVMTI_KIND_IN_BUF93 Ingoing array argument -const foo*.JVMTI_KIND_ALLOC_BUF94 Outgoing allocated array argument -foo**. Free withDeallocate.JVMTI_KIND_ALLOC_ALLOC_BUF95 Outgoing allocated array of allocated arrays argument -foo***. Free withDeallocate.JVMTI_KIND_OUT96 Outgoing argument -foo*.JVMTI_KIND_OUT_BUF97 Outgoing array argument (pre-allocated by agent) -foo*. Do notDeallocate.
Extension Functiontypedef struct { char* name; jvmtiParamKind kind; jvmtiParamTypes base_type; jboolean null_ok; } jvmtiParamInfo;jvmtiParamInfo- Extension Function/Event Parameter Info Field Type Descriptionnamechar*The parameter name, encoded as a modified UTF-8 stringkindjvmtiParamKindThe kind of the parameter - type modifiersbase_typejvmtiParamTypesThe base type of the parameter - modified bykindnull_okjbooleanIs aNULLargument permitted? Applies only to pointer and object types.
typedef jvmtiError (JNICALL *jvmtiExtensionFunction)
(jvmtiEnv* jvmti_env,
...);
This is the implementation-specific extension function.
Parameters Name Type Descriptionjvmti_env jvmtiEnv * The JVM TI environment is the only fixed parameter for extension functions. ... ... The extension function-specific parameters Get Extension Functions
Returns the set of extension functions.typedef struct { jvmtiExtensionFunction func; char* id; char* short_description; jint param_count; jvmtiParamInfo* params; jint error_count; jvmtiError* errors; } jvmtiExtensionFunctionInfo;jvmtiError GetExtensionFunctions(jvmtiEnv* env, jint* extension_count_ptr, jvmtiExtensionFunctionInfo** extensions)
may only be called during the OnLoad or the live phase
No
124
1.0
Capabilities
Required Functionality
jvmtiExtensionFunctionInfo - Extension Function Info Field Type Description func jvmtiExtensionFunction The actual function to call id char* The identifier for the extension function, encoded as a modified UTF-8 string. Uses package name conventions. For example, com.sun.hotspot.bar short_description char* A one sentence description of the function, encoded as a modified UTF-8 string. param_count jint The number of parameters excluding jvmtiEnv *jvmti_env params jvmtiParamInfo * Array of param_count parameters (jvmtiEnv *jvmti_env excluded) error_count jint The number of possible error returns (excluding universal errors) errors jvmtiError * Array of error_count possible errors Parameters Name Type Description extension_count_ptr jint* On return, points to the number of extension functions Agent passes a pointer to a jint. On return, the jint has been set. extensions jvmtiExtensionFunctionInfo** Returns an array of extension function info, one per function Agent passes a pointer to a jvmtiExtensionFunctionInfo*. On return, the jvmtiExtensionFunctionInfo* points to a newly allocated array of size *extension_count_ptr. The array should be freed with Deallocate. The pointers returned in the field id of jvmtiExtensionFunctionInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field short_description of jvmtiExtensionFunctionInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field params of jvmtiExtensionFunctionInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field name of jvmtiParamInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field errors of jvmtiExtensionFunctionInfo are newly allocated arrays. The arrays should be freed with Deallocate. Get Extension Events
Returns the set of extension events.typedef struct { jint extension_event_index; char* id; char* short_description; jint param_count; jvmtiParamInfo* params; } jvmtiExtensionEventInfo;jvmtiError GetExtensionEvents(jvmtiEnv* env, jint* extension_count_ptr, jvmtiExtensionEventInfo** extensions)
may only be called during the OnLoad or the live phase
No
125
1.0
Capabilities
Required Functionality
jvmtiExtensionEventInfo - Extension Event Info Field Type Description extension_event_index jint The identifying index of the event id char* The identifier for the extension event, encoded as a modified UTF-8 string. Uses package name conventions. For example, com.sun.hotspot.bar short_description char* A one sentence description of the event, encoded as a modified UTF-8 string. param_count jint The number of parameters excluding jvmtiEnv *jvmti_env params jvmtiParamInfo * Array of param_count parameters (jvmtiEnv *jvmti_env excluded) Parameters Name Type Description extension_count_ptr jint* On return, points to the number of extension events Agent passes a pointer to a jint. On return, the jint has been set. extensions jvmtiExtensionEventInfo** Returns an array of extension event info, one per event Agent passes a pointer to a jvmtiExtensionEventInfo*. On return, the jvmtiExtensionEventInfo* points to a newly allocated array of size *extension_count_ptr. The array should be freed with Deallocate. The pointers returned in the field id of jvmtiExtensionEventInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field short_description of jvmtiExtensionEventInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field params of jvmtiExtensionEventInfo are newly allocated arrays. The arrays should be freed with Deallocate. The pointers returned in the field name of jvmtiParamInfo are newly allocated arrays. The arrays should be freed with Deallocate. Extension Event
typedef void (JNICALL *jvmtiExtensionEvent)
(jvmtiEnv* jvmti_env,
...);
This is the implementation-specific event. The event handler is set with
SetExtensionEventCallback
.
Event handlers for extension events must be declared varargs to match this definition. Failure to do so could result in calling convention mismatch and undefined behavior on some platforms.
For example, if the
jvmtiParamInfo
returned by
GetExtensionEvents
indicates that there is a
jint
parameter, the event handler should be declared:
void JNICALL myHandler(jvmtiEnv* jvmti_env, ...)
Note the terminal "
...
" which indicates varargs. The
jint
argument inside
myHandler
needs to be extracted using the
va_*
syntax of the C programming language.
Parameters Name Type Descriptionjvmti_env jvmtiEnv * The JVM TI environment is the only fixed parameter for extension events. ... ... The extension event-specific parameters Set Extension Event Callback
jvmtiError
SetExtensionEventCallback(jvmtiEnv* env,
jint extension_event_index,
jvmtiExtensionEvent callback)
Sets the callback function for an extension event and enables the event. Or, if the callback is NULL, disables the event. Note that unlike standard events, setting the callback and enabling the event are a single operation.
may only be called during the OnLoad or the live phase
No
126
1.0
Capabilities
Required Functionality
Capability Capability functions: Capability types:jvmtiCapabilities - The Capabilities StructureOnLoad or live phase in any environmentOnLoad phaseOnLoad phaseOnLoad phase (before bytecode execution begins) and would have a large impact on execution speed even if single stepping was never used.OnLoad phase but the overhead (a test and branch on each instruction) would be considerably less.OnLoad phase. For most virtual machines certain capabilities require special set up for the virtual machine and this set up must happen during the OnLoad phase, before the virtual machine begins execution. Once a capability is added, it can only be removed if explicitly relinquished by the environment. The agent can, determine what capabilities this VM can potentially provide, add the capabilities to be used, release capabilities which are no longer needed, and examine the currently available capabilities. Capability Examples For example, a freshly started agent (in the OnLoad function) wants to enable all possible capabilities. Note that, in general, this is not advisable as the agent may suffer a performance penalty for functionality it is not using. The code might look like this in C:
jvmtiCapabilities capa;
jvmtiError err;
err = (*jvmti)->GetPotentialCapabilities(jvmti, &capa);
if (err == JVMTI_ERROR_NONE) {
err = (*jvmti)->AddCapabilities(jvmti, &capa);
For example, if an agent wants to check if it can get the bytecodes of a method (that is, it wants to check if it previously added this capability and has not relinquished it), the code might look like this in C:
jvmtiCapabilities capa;
jvmtiError err;
err = (*jvmti)->GetCapabilities(jvmti, &capa);
if (err == JVMTI_ERROR_NONE) {
if (capa.can_get_bytecodes) { ... } }
The Capabilities Structure The functions in this category use this capabilities structure which contains boolean flags corresponding to each capability:
Get Potential Capabilitiestypedef struct { unsigned int can_tag_objects : 1; unsigned int can_generate_field_modification_events : 1; unsigned int can_generate_field_access_events : 1; unsigned int can_get_bytecodes : 1; unsigned int can_get_synthetic_attribute : 1; unsigned int can_get_owned_monitor_info : 1; unsigned int can_get_current_contended_monitor : 1; unsigned int can_get_monitor_info : 1; unsigned int can_pop_frame : 1; unsigned int can_redefine_classes : 1; unsigned int can_signal_thread : 1; unsigned int can_get_source_file_name : 1; unsigned int can_get_line_numbers : 1; unsigned int can_get_source_debug_extension : 1; unsigned int can_access_local_variables : 1; unsigned int can_maintain_original_method_order : 1; unsigned int can_generate_single_step_events : 1; unsigned int can_generate_exception_events : 1; unsigned int can_generate_frame_pop_events : 1; unsigned int can_generate_breakpoint_events : 1; unsigned int can_suspend : 1; unsigned int can_redefine_any_class : 1; unsigned int can_get_current_thread_cpu_time : 1; unsigned int can_get_thread_cpu_time : 1; unsigned int can_generate_method_entry_events : 1; unsigned int can_generate_method_exit_events : 1; unsigned int can_generate_all_class_hook_events : 1; unsigned int can_generate_compiled_method_load_events : 1; unsigned int can_generate_monitor_events : 1; unsigned int can_generate_vm_object_alloc_events : 1; unsigned int can_generate_native_method_bind_events : 1; unsigned int can_generate_garbage_collection_events : 1; unsigned int can_generate_object_free_events : 1; unsigned int can_force_early_return : 1; unsigned int can_get_owned_monitor_stack_depth_info : 1; unsigned int can_get_constant_pool : 1; unsigned int can_set_native_method_prefix : 1; unsigned int can_retransform_classes : 1; unsigned int can_retransform_any_class : 1; unsigned int can_generate_resource_exhaustion_heap_events : 1; unsigned int can_generate_resource_exhaustion_threads_events : 1; unsigned int can_generate_early_vmstart : 1; unsigned int can_generate_early_class_hook_events : 1; unsigned int can_generate_sampled_object_alloc_events : 1; unsigned int can_support_virtual_threads : 1; unsigned int : 3; unsigned int : 16; unsigned int : 16; unsigned int : 16; unsigned int : 16; unsigned int : 16; } jvmtiCapabilities;
jvmtiCapabilities- The Capabilities StructureAll types are
Field Description Sinceunsigned int : 1can_tag_objectsCan set and get tags, as described in the Heap category. 1.0can_generate_field_modification_eventsCan set watchpoints on field modification -SetFieldModificationWatch1.0can_generate_field_access_eventsCan set watchpoints on field access -SetFieldAccessWatch1.0can_get_bytecodesCan get bytecodes of a methodGetBytecodes1.0can_get_synthetic_attributeCan test if a field or method is synthetic -IsFieldSyntheticandIsMethodSynthetic1.0can_get_owned_monitor_infoCan get information about ownership of monitors -GetOwnedMonitorInfo1.0can_get_current_contended_monitorCanGetCurrentContendedMonitor1.0can_get_monitor_infoCanGetObjectMonitorUsage1.0can_pop_frameCan pop frames off the stack -PopFrame1.0can_redefine_classesCan redefine classes withRedefineClasses. 1.0can_signal_threadCan send stop or interrupt to threads 1.0can_get_source_file_nameCan get the source file name of a class 1.0can_get_line_numbersCan get the line number table of a method 1.0can_get_source_debug_extensionCan get the source debug extension of a class 1.0can_access_local_variablesCan set and get local variables 1.0can_maintain_original_method_orderCan return methods in the order they occur in the class file 1.0can_generate_single_step_eventsCan get single step events 1.0can_generate_exception_eventsCan get exception thrown and exception catch events 1.0can_generate_frame_pop_eventsCan set and thus getFramePopevents 1.0can_generate_breakpoint_eventsCan set and thus getBreakpointevents 1.0can_suspendCan suspend and resume threads 1.0can_redefine_any_classRedefineClassescan be called on any modifiable class. SeeIsModifiableClass. (can_redefine_classesmust also be set) 1.0can_get_current_thread_cpu_timeCan get current thread CPU time 1.0can_get_thread_cpu_timeCan get thread CPU time 1.0can_generateCan generate method entry events on entering a method 1.0
_method_entry_eventscan_generateCan generate method exit events on leaving a method 1.0
_method_exit_eventscan_generateCan generate ClassFileLoadHook events for every loaded class. 1.0
_all_class_hook_eventscan_generateCan generate events when a method is compiled or unloaded 1.0
_compiled_method_load_eventscan_generateCan generate events on monitor activity 1.0
_monitor_eventscan_generateCan generate events on VM allocation of an object 1.0
_vm_object_alloc_eventscan_generateCan generate events when a native method is bound to its implementation 1.0
_native_method_bind_eventscan_generateCan generate events when garbage collection begins or ends 1.0
_garbage_collection_eventscan_generateCan generate events when the garbage collector frees an object 1.0
_object_free_eventscan_force_early_returnCan return early from a method, as described in the Force Early Return category. 1.1can_get_owned_monitor_stack_depth_infoCan get information about owned monitors with stack depth -GetOwnedMonitorStackDepthInfo1.1can_get_constant_poolCan get the constant pool of a class -GetConstantPool1.1can_set_native_method_prefixCan set prefix to be applied when native method cannot be resolved -SetNativeMethodPrefixandSetNativeMethodPrefixes1.1can_retransform_classesCan retransform classes withRetransformClasses. In addition to the restrictions imposed by the specific implementation on this capability (see the Capability section), this capability must be set before theClassFileLoadHookevent is enabled for the first time in this environment. An environment that possesses this capability at the time thatClassFileLoadHookis enabled for the first time is said to be retransformation capable. An environment that does not possess this capability at the time thatClassFileLoadHookis enabled for the first time is said to be retransformation incapable. 1.1can_retransform_any_classRetransformClassescan be called on any modifiable class. SeeIsModifiableClass. (can_retransform_classesmust also be set) 1.1can_generate_resource_exhaustion_heap_eventsCan generate events when the VM is unable to allocate memory from the JavaTM platform heap. SeeResourceExhausted. 1.1can_generate_resource_exhaustion_threads_eventsCan generate events when the VM is unable to create a thread. SeeResourceExhausted. 1.1can_generate_early_vmstartCan generate theVMStartevent early. SeeVMStart. 9can_generate_early_class_hook_eventsCan generate theClassFileLoadHookevents in the primordial phase. If this capability andcan_generate_all_class_hook_eventsare enabled then theClassFileLoadHookevents can be posted for classes loaded in the primordial phase. SeeClassFileLoadHook. 9can_generate_sampled_object_alloc_eventsCan generate sampled allocation events. If this capability is enabled then the heap sampling methodSetHeapSamplingIntervalcan be called andSampledObjectAllocevents can be generated. 11can_support_virtual_threadscan_support_virtual_threads is a preview API of the Java platform. Preview features may be removed in a future release, or upgraded to permanent features of the Java platform. Can support virtual threads. If this capability is enabled then the following functions can be called:SuspendAllVirtualThreads,ResumeAllVirtualThreads, and the following events can be enabled:VirtualThreadStart,VirtualThreadEnd. 19
jvmtiError
GetPotentialCapabilities(jvmtiEnv* env,
jvmtiCapabilities* capabilities_ptr)
Returns via capabilities_ptr the JVM TI features that can potentially be possessed by this environment at this time. The returned capabilities differ from the complete set of capabilities implemented by the VM in two cases: another environment possesses capabilities that can only be possessed by one environment, or the current phase is live, and certain capabilities can only be added during the OnLoad phase. The AddCapabilities function may be used to set any or all or these capabilities. Currently possessed capabilities are included. Typically this function is used in the OnLoad function. Some virtual machines may allow a limited set of capabilities to be added in the live phase. In this case, the set of potentially available capabilities will likely differ from the OnLoad phase set. See the Capability Examples.
may only be called during the OnLoad or the live phase
No
140
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncapabilities_ptr jvmtiCapabilities* On return, points to the JVM TI capabilities that may be added. Agent passes a pointer to a jvmtiCapabilities. On return, the jvmtiCapabilities has been set. Add Capabilities
jvmtiError
AddCapabilities(jvmtiEnv* env,
const jvmtiCapabilities* capabilities_ptr)
Set new capabilities by adding the capabilities whose values are set to one (1) in *capabilities_ptr. All previous capabilities are retained. Typically this function is used in the OnLoad function. Some virtual machines may allow a limited set of capabilities to be added in the live phase. See the Capability Examples.
may only be called during the OnLoad or the live phase
No
142
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncapabilities_ptr const jvmtiCapabilities* Points to the JVM TI capabilities to add. Agent passes in a pointer to jvmtiCapabilities. Relinquish Capabilities
jvmtiError
RelinquishCapabilities(jvmtiEnv* env,
const jvmtiCapabilities* capabilities_ptr)
Relinquish the capabilities whose values are set to one (1) in *capabilities_ptr. Some implementations may allow only one environment to have a capability (see the capability introduction). This function releases capabilities so that they may be used by other agents. All other capabilities are retained. The capability will no longer be present in GetCapabilities. Attempting to relinquish a capability that the agent does not possess is not an error.
may only be called during the OnLoad or the live phase
No
143
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncapabilities_ptr const jvmtiCapabilities* Points to the JVM TI capabilities to relinquish. Agent passes in a pointer to jvmtiCapabilities. Get Capabilities
jvmtiError
GetCapabilities(jvmtiEnv* env,
jvmtiCapabilities* capabilities_ptr)
Returns via capabilities_ptr the optional JVM TI features which this environment currently possesses. Each possessed capability is indicated by a one (1) in the corresponding field of the capabilities structure. An environment does not possess a capability unless it has been successfully added with AddCapabilities. An environment only loses possession of a capability if it has been relinquished with RelinquishCapabilities. Thus, this function returns the net result of the AddCapabilities and RelinquishCapabilities calls which have been made. See the Capability Examples.
may be called during any phase
No
89
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncapabilities_ptr jvmtiCapabilities* On return, points to the JVM TI capabilities. Agent passes a pointer to a jvmtiCapabilities. On return, the jvmtiCapabilities has been set. Timers Timers functions:
jvmtiTimerInfo - Timer InfojvmtiTimerKind - Timer KindsWhere the timer kind is --typedef struct { jlong max_value; jboolean may_skip_forward; jboolean may_skip_backward; jvmtiTimerKind kind; jlong reserved1; jlong reserved2; } jvmtiTimerInfo;jvmtiTimerInfo- Timer Info Field Type Descriptionmax_valuejlongThe maximum value the timer can reach. After this value is reached the timer wraps back to zero. This is an unsigned value. If tested or printed as a jlong (signed value) it may appear to be a negative number.may_skip_forwardjbooleanIf true, the timer can be externally adjusted and as a result skip forward. If false, the timer value will never increase faster than real time.may_skip_backwardjbooleanIf true, the timer can be externally adjusted and as a result skip backward. If false, the timer value will be monotonically increasing.kindjvmtiTimerKindThe kind of timer. On a platform that does not distinguish between user and system time,JVMTI_TIMER_TOTAL_CPUis returned.reserved1jlongReserved for future use.reserved2jlongReserved for future use.
Timer Kinds (Get Current Thread CPU Timer InformationjvmtiTimerKind) Constant Value DescriptionJVMTI_TIMER_USER_CPU30 CPU time that a thread is in user mode.JVMTI_TIMER_TOTAL_CPU31 CPU time that a thread is in user or system mode.JVMTI_TIMER_ELAPSED32 Elapsed time.
jvmtiError
GetCurrentThreadCpuTimerInfo(jvmtiEnv* env,
jvmtiTimerInfo* info_ptr)
Get information about the GetCurrentThreadCpuTime timer. The fields of the jvmtiTimerInfo structure are filled in with details about the timer. This information is specific to the platform and the implementation of GetCurrentThreadCpuTime and thus does not vary by thread nor does it vary during a particular invocation of the VM. Note that the implementations of GetCurrentThreadCpuTime and GetThreadCpuTime may differ, and thus the values returned by GetCurrentThreadCpuTimerInfo and GetThreadCpuTimerInfo may differ -- see GetCurrentThreadCpuTime for more information.
may only be called during the start or the live phase
134
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_current_thread_cpu_time Can get current thread CPU time. Parameters Name Type Description info_ptr jvmtiTimerInfo* On return, filled with information describing the time returned by GetCurrentThreadCpuTime. Agent passes a pointer to a jvmtiTimerInfo. On return, the jvmtiTimerInfo has been set. Get Current Thread CPU Time
jvmtiError
GetCurrentThreadCpuTime(jvmtiEnv* env,
jlong* nanos_ptr)
Return the CPU time utilized by the current thread. Note that the GetThreadCpuTime function provides CPU time for any thread, including the current thread. GetCurrentThreadCpuTime exists to support platforms which cannot supply CPU time for threads other than the current thread or which have more accurate information for the current thread (see GetCurrentThreadCpuTimerInfo vs GetThreadCpuTimerInfo). The current thread may not be a virtual thread. Otherwise, the error code JVMTI_ERROR_UNSUPPORTED_OPERATION will be returned. On many platforms this call will be equivalent to:
GetThreadCpuTime(env, NULL, nanos_ptr)
may only be called during the start or the live phase
135
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_current_thread_cpu_time Can get current thread CPU time. If this capability is enabled after threads have started, the implementation may choose any time up to and including the time that the capability is enabled as the point where CPU time collection starts. This capability must be potentially available on any platform where can_get_thread_cpu_time is potentially available. Parameters Name Type Description nanos_ptr jlong* On return, points to the CPU time used by this thread in nanoseconds. This is an unsigned value. If tested or printed as a jlong (signed value) it may appear to be a negative number. Agent passes a pointer to a jlong. On return, the jlong has been set. Get Thread CPU Timer Information
jvmtiError
GetThreadCpuTimerInfo(jvmtiEnv* env,
jvmtiTimerInfo* info_ptr)
Get information about the GetThreadCpuTime timer. The fields of the jvmtiTimerInfo structure are filled in with details about the timer. This information is specific to the platform and the implementation of GetThreadCpuTime and thus does not vary by thread nor does it vary during a particular invocation of the VM. Note that the implementations of GetCurrentThreadCpuTime and GetThreadCpuTime may differ, and thus the values returned by GetCurrentThreadCpuTimerInfo and GetThreadCpuTimerInfo may differ -- see GetCurrentThreadCpuTime for more information.
may only be called during the live phase
No
136
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_thread_cpu_time Can get thread CPU time. Parameters Name Type Description info_ptr jvmtiTimerInfo* On return, filled with information describing the time returned by GetThreadCpuTime. Agent passes a pointer to a jvmtiTimerInfo. On return, the jvmtiTimerInfo has been set. Get Thread CPU Time
jvmtiError
GetThreadCpuTime(jvmtiEnv* env,
jthread thread,
jlong* nanos_ptr)
Return the CPU time utilized by the specified thread. Get information about this timer with GetThreadCpuTimerInfo.
may only be called during the live phase
No
137
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this function.
Capability Effectcan_get_thread_cpu_time Can get thread CPU time. If this capability is enabled after threads have started, the implementation may choose any time up to and including the time that the capability is enabled as the point where CPU time collection starts. Parameters Name Type Description thread jthread The thread to query. The thread may not be a virtual thread. Otherwise, the error code JVMTI_ERROR_UNSUPPORTED_OPERATION will be returned. If thread is NULL, the current thread is used. nanos_ptr jlong* On return, points to the CPU time used by the specified thread in nanoseconds. This is an unsigned value. If tested or printed as a jlong (signed value) it may appear to be a negative number. Agent passes a pointer to a jlong. On return, the jlong has been set. Get Timer Information
jvmtiError
GetTimerInfo(jvmtiEnv* env,
jvmtiTimerInfo* info_ptr)
Get information about the GetTime timer. The fields of the jvmtiTimerInfo structure are filled in with details about the timer. This information will not change during a particular invocation of the VM.
may be called during any phase
138
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioninfo_ptr jvmtiTimerInfo* On return, filled with information describing the time returned by GetTime. Agent passes a pointer to a jvmtiTimerInfo. On return, the jvmtiTimerInfo has been set. Get Time
jvmtiError
GetTime(jvmtiEnv* env,
jlong* nanos_ptr)
Return the current value of the system timer, in nanoseconds. The value returned represents nanoseconds since some fixed but arbitrary time (perhaps in the future, so values may be negative). This function provides nanosecond precision, but not necessarily nanosecond accuracy. No guarantees are made about how frequently values change. Get information about this timer with GetTimerInfo.
may be called during any phase
139
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionnanos_ptr jlong* On return, points to the time in nanoseconds. This is an unsigned value. If tested or printed as a jlong (signed value) it may appear to be a negative number. Agent passes a pointer to a jlong. On return, the jlong has been set. Get Available Processors
jvmtiError
GetAvailableProcessors(jvmtiEnv* env,
jint* processor_count_ptr)
Returns the number of processors available to the Java virtual machine. This value may change during a particular invocation of the virtual machine. Applications that are sensitive to the number of available processors should therefore occasionally poll this property.
may be called during any phase
No
144
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionprocessor_count_ptr jint* On return, points to the maximum number of processors available to the virtual machine; never smaller than one. Agent passes a pointer to a jint. On return, the jint has been set. Class Loader Search Class Loader Search functions:
These functions allow the agent to add to the locations that a class loader searches for a class. This is useful for installing instrumentation under the correct class loader. Add To Bootstrap Class Loader Search
jvmtiError
AddToBootstrapClassLoaderSearch(jvmtiEnv* env,
const char* segment)
This function can be used to cause instrumentation classes to be defined by the bootstrap class loader. See The Java™ Virtual Machine Specification, Chapter 5.3.1. After the bootstrap class loader unsuccessfully searches for a class, the specified platform-dependent search path segment will be searched as well. Only one segment may be specified in the segment. This function may be called multiple times to add multiple segments, the segments will be searched in the order that this function was called. In the OnLoad phase the function may be used to specify any platform-dependent search path segment to be searched after the bootstrap class loader unsuccessfully searches for a class. The segment is typically a directory or JAR file. In the live phase the segment may be used to specify any platform-dependent path to a JAR file. The agent should take care that the JAR file does not contain any classes or resources other than those to be defined by the bootstrap class loader for the purposes of instrumentation. The Java™ Virtual Machine Specification specifies that a subsequent attempt to resolve a symbolic reference that the Java virtual machine has previously unsuccessfully attempted to resolve always fails with the same error that was thrown as a result of the initial resolution attempt. Consequently, if the JAR file contains an entry that corresponds to a class for which the Java virtual machine has unsuccessfully attempted to resolve a reference, then subsequent attempts to resolve that reference will fail with the same error as the initial attempt.
may only be called during the OnLoad or the live phase
No
149
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionsegment const char* The platform-dependent search path segment, encoded as a modified UTF-8 string. Agent passes in an array of char. Add To System Class Loader Search
jvmtiError
AddToSystemClassLoaderSearch(jvmtiEnv* env,
const char* segment)
This function can be used to cause instrumentation classes to be defined by the system class loader. See The Java™ Virtual Machine Specification, Chapter 5.3.2. After the class loader unsuccessfully searches for a class, the specified platform-dependent search path segment will be searched as well. Only one segment may be specified in the segment. This function may be called multiple times to add multiple segments, the segments will be searched in the order that this function was called. In the OnLoad phase the function may be used to specify any platform-dependent search path segment to be searched after the system class loader unsuccessfully searches for a class. The segment is typically a directory or JAR file. In the live phase the segment is a platform-dependent path to a JAR file to be searched after the system class loader unsuccessfully searches for a class. The agent should take care that the JAR file does not contain any classes or resources other than those to be defined by the system class loader for the purposes of instrumentation. In the live phase the system class loader supports adding a JAR file to be searched if the system class loader implements a method name appendToClassPathForInstrumentation which takes a single parameter of type java.lang.String. The method is not required to have public access. The Java™ Virtual Machine Specification specifies that a subsequent attempt to resolve a symbolic reference that the Java virtual machine has previously unsuccessfully attempted to resolve always fails with the same error that was thrown as a result of the initial resolution attempt. Consequently, if the JAR file contains an entry that corresponds to a class for which the Java virtual machine has unsuccessfully attempted to resolve a reference, then subsequent attempts to resolve that reference will fail with the same error as the initial attempt.
may only be called during the OnLoad or the live phase
No
151
1.1
Capabilities
Required Functionality
Parameters Name Type Descriptionsegment const char* The platform-dependent search path segment, encoded as a modified UTF-8 string. Agent passes in an array of char. System Properties System Properties functions:
These functions get and set system properties. Get System Properties
jvmtiError
GetSystemProperties(jvmtiEnv* env,
jint* count_ptr,
char*** property_ptr)
The list of VM system property keys which may be used with GetSystemProperty is returned. It is strongly recommended that virtual machines provide the following property keys:
java.vm.vendorjava.vm.versionjava.vm.namejava.vm.infojava.library.pathjava.class.pathjava.lang.System.getProperties. JNI method invocation may be used to access java.lang.System.getProperties. The set of properties may grow during execution.
may only be called during the OnLoad or the live phase
No
130
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptioncount_ptr jint* On return, points to the number of property keys returned. Agent passes a pointer to a jint. On return, the jint has been set. property_ptr char*** On return, points to an array of property keys, encoded as modified UTF-8 strings. Agent passes a pointer to a char**. On return, the char** points to a newly allocated array of size *count_ptr, each element of which is also newly allocated. The array should be freed with Deallocate. Each of the elements should be freed with Deallocate. Get System Property
jvmtiError
GetSystemProperty(jvmtiEnv* env,
const char* property,
char** value_ptr)
Return a VM system property value given the property key. The function GetSystemProperties returns the set of property keys which may be used. The properties which can be retrieved may grow during execution. Since this is a VM view of system properties, the values of properties may differ from that returned by java.lang.System.getProperty(String). A typical VM might copy the values of the VM system properties into the Properties held by java.lang.System during the initialization of that class. Thereafter any changes to the VM system properties (with SetSystemProperty) or the java.lang.System system properties (with java.lang.System.setProperty(String,String)) would cause the values to diverge. JNI method invocation may be used to access java.lang.System.getProperty(String).
may only be called during the OnLoad or the live phase
No
131
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionproperty const char* The key of the property to retrieve, encoded as a modified UTF-8 string. Agent passes in an array of char. value_ptr char** On return, points to the property value, encoded as a modified UTF-8 string. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. Set System Property
jvmtiError
SetSystemProperty(jvmtiEnv* env,
const char* property,
const char* value_ptr)
Set a VM system property value. The function GetSystemProperties returns the set of property keys, some of these may be settable. See GetSystemProperty.
may only be called during the OnLoad phase
No
132
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionproperty const char* The key of the property, encoded as a modified UTF-8 string. Agent passes in an array of char. value_ptr const char * The property value to set, encoded as a modified UTF-8 string. Agent passes in an array of char. If value_ptr is NULL, do not set the value, but return JVMTI_ERROR_NOT_AVAILABLE if the property is not writeable . General General functions:
jvmtiPhase - Phases of executionjvmtiVerboseFlag - Verbose Flag EnumerationjvmtiJlocationFormat - JLocation Format EnumerationReturn the current phase of VM execution. The phases proceed in sequence:typedef enum { JVMTI_PHASE_ONLOAD = 1, JVMTI_PHASE_PRIMORDIAL = 2, JVMTI_PHASE_START = 6, JVMTI_PHASE_LIVE = 4, JVMTI_PHASE_DEAD = 8 } jvmtiPhase;jvmtiError GetPhase(jvmtiEnv* env, jvmtiPhase* phase_ptr)
Phases of execution (In the case of start-up failure the VM will proceed directly to the dead phase skipping intermediate phases and neither ajvmtiPhase) Constant Value DescriptionJVMTI_PHASE_ONLOAD1OnLoadphase: while in theAgent_OnLoador, for statically linked agents, theAgent_OnLoad_<agent-lib-name>function.JVMTI_PHASE_PRIMORDIAL2 Primordial phase: between return fromAgent_OnLoadorAgent_OnLoad_<agent-lib-name>and theVMStartevent.JVMTI_PHASE_START6 Start phase: when theVMStartevent is sent and until theVMInitevent is sent.JVMTI_PHASE_LIVE4 Live phase: when theVMInitevent is sent and until theVMDeathevent returns.JVMTI_PHASE_DEAD8 Dead phase: after theVMDeathevent returns or after start-up failure.
VMInit nor VMDeath event will be sent. Most JVM TI functions operate only in the live phase. The following functions operate in either the OnLoad or live phases:
OnLoad phase:
The following functions operate in the start or live phases:
may be called during any phase
No
133
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionphase_ptr jvmtiPhase* On return, points to the phase. Agent passes a pointer to a jvmtiPhase. On return, the jvmtiPhase has been set. Dispose Environment
Shutdown a JVM TI connection created with JNIjvmtiError DisposeEnvironment(jvmtiEnv* env)
GetEnv (see JVM TI Environments). Dispose of any resources held by the environment. Threads suspended by this environment are not resumed by this call, this must be done explicitly by the agent. Memory allocated by this environment via calls to JVM TI functions is not released, this can be done explicitly by the agent by calling Deallocate. Raw monitors created by this environment are not destroyed, this can be done explicitly by the agent by calling DestroyRawMonitor. The state of threads waiting on raw monitors created by this environment are not affected. Any native method prefixes for this environment will be unset; the agent must remove any prefixed native methods before dispose is called. Any capabilities held by this environment are relinquished. Events enabled by this environment will no longer be sent, however event handlers currently running will continue to run. Caution must be exercised in the design of event handlers whose environment may be disposed and thus become invalid during their execution. This environment may not be used after this call. This call returns to the caller.
may be called during any phase
No
127
1.0
Capabilities
Required Functionality
Set Environment Local Storage
jvmtiError
SetEnvironmentLocalStorage(jvmtiEnv* env,
const void* data)
The VM stores a pointer value associated with each environment. This pointer value is called environment-local storage. This value is NULL unless set with this function. Agents can allocate memory in which they store environment specific information. By setting environment-local storage it can then be accessed with GetEnvironmentLocalStorage. Called by the agent to set the value of the JVM TI environment-local storage. JVM TI supplies to the agent a pointer-size environment-local storage that can be used to record per-environment information.
may be called during any phase
148
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptiondata const void * The value to be entered into the environment-local storage. Agent passes in a pointer. If data is NULL, value is set to NULL. Get Environment Local Storage
jvmtiError
GetEnvironmentLocalStorage(jvmtiEnv* env,
void** data_ptr)
Called by the agent to get the value of the JVM TI environment-local storage.
may be called during any phase
147
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptiondata_ptr void** Pointer through which the value of the environment local storage is returned. If environment-local storage has not been set with SetEnvironmentLocalStorage returned pointer is NULL. Get Version Number
jvmtiError
GetVersionNumber(jvmtiEnv* env,
jint* version_ptr)
Return the JVM TI version via version_ptr. The return value is the version identifier. The version identifier includes major, minor and micro version as well as the interface type.
Version Interface Types Constant Value DescriptionJVMTI_VERSION_INTERFACE_JNI0x00000000 Value ofJVMTI_VERSION_MASK_INTERFACE_TYPEfor JNI.JVMTI_VERSION_INTERFACE_JVMTI0x30000000 Value ofJVMTI_VERSION_MASK_INTERFACE_TYPEfor JVM TI.
Version Masks Constant Value DescriptionJVMTI_VERSION_MASK_INTERFACE_TYPE0x70000000 Mask to extract interface type. The value of the version returned by this function masked withJVMTI_VERSION_MASK_INTERFACE_TYPEis alwaysJVMTI_VERSION_INTERFACE_JVMTIsince this is a JVM TI function.JVMTI_VERSION_MASK_MAJOR0x0FFF0000 Mask to extract major version number.JVMTI_VERSION_MASK_MINOR0x0000FF00 Mask to extract minor version number.JVMTI_VERSION_MASK_MICRO0x000000FF Mask to extract micro version number.
Version Shifts Constant Value DescriptionJVMTI_VERSION_SHIFT_MAJOR16 Shift to extract major version number.JVMTI_VERSION_SHIFT_MINOR8 Shift to extract minor version number.JVMTI_VERSION_SHIFT_MICRO0 Shift to extract micro version number.
may be called during any phase
No
88
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionversion_ptr jint* On return, points to the JVM TI version. Agent passes a pointer to a jint. On return, the jint has been set. Get Error Name
jvmtiError
GetErrorName(jvmtiEnv* env,
jvmtiError error,
char** name_ptr)
Return the symbolic name for an error code. For example GetErrorName(env, JVMTI_ERROR_NONE, &err_name) would return in err_name the string "JVMTI_ERROR_NONE".
may be called during any phase
No
128
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionerror jvmtiError The error code. name_ptr char** On return, points to the error name. The name is encoded as a modified UTF-8 string, but is restricted to the ASCII subset. Agent passes a pointer to a char*. On return, the char* points to a newly allocated array. The array should be freed with Deallocate. Set Verbose Flag
typedef enum { JVMTI_VERBOSE_OTHER = 0, JVMTI_VERBOSE_GC = 1, JVMTI_VERBOSE_CLASS = 2, JVMTI_VERBOSE_JNI = 4 } jvmtiVerboseFlag;jvmtiError SetVerboseFlag(jvmtiEnv* env, jvmtiVerboseFlag flag, jboolean value)
Verbose Flag Enumeration (Control verbose output. This is the output which typically is sent tojvmtiVerboseFlag) Constant Value DescriptionJVMTI_VERBOSE_OTHER0 Verbose output other than the below.JVMTI_VERBOSE_GC1 Verbose garbage collector output, like that specified with-verbose:gc.JVMTI_VERBOSE_CLASS2 Verbose class loading output, like that specified with-verbose:class.JVMTI_VERBOSE_JNI4 Verbose JNI output, like that specified with-verbose:jni.
stderr.
may be called during any phase
No
150
1.0
Capabilities
Required Functionality
Get JLocation FormatAlthough the greatest functionality is achieved with location information referencing the virtual machine bytecode index, the definition oftypedef enum { JVMTI_JLOCATION_JVMBCI = 1, JVMTI_JLOCATION_MACHINEPC = 2, JVMTI_JLOCATION_OTHER = 0 } jvmtiJlocationFormat;jvmtiError GetJLocationFormat(jvmtiEnv* env, jvmtiJlocationFormat* format_ptr)
jlocation has intentionally been left unconstrained to allow VM implementations that do not have this information. This function describes the representation of jlocation used in this VM. If the returned format is JVMTI_JLOCATION_JVMBCI, jlocations can be used as in indices into the array returned by GetBytecodes.
JLocation Format Enumeration (jvmtiJlocationFormat) Constant Value DescriptionJVMTI_JLOCATION_JVMBCI1jlocationvalues represent virtual machine bytecode indices--that is, offsets into the virtual machine code for a method.JVMTI_JLOCATION_MACHINEPC2jlocationvalues represent native machine program counter values.JVMTI_JLOCATION_OTHER0jlocationvalues have some other representation.
may be called during any phase
No
129
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionformat_ptr jvmtiJlocationFormat* On return, points to the format identifier for jlocation values. Agent passes a pointer to a jvmtiJlocationFormat. On return, the jvmtiJlocationFormat has been set. Heap Monitoring Heap Monitoring functions:
Set Heap Sampling Interval
jvmtiError
SetHeapSamplingInterval(jvmtiEnv* env,
jint sampling_interval)
Generate a SampledObjectAlloc event when objects are allocated. Each thread keeps a counter of bytes allocated. The event will only be generated when that counter exceeds an average of sampling_interval since the last sample. Setting sampling_interval to 0 will cause an event to be generated by each allocation supported by the system once the new interval is taken into account. Note that updating the new sampling interval might take various number of allocations to provoke internal data structure updates. Therefore it is important to consider the sampling interval as an average. This includes the interval 0, where events might not be generated straight away for each allocation.
may only be called during the OnLoad or the live phase
No
156
11
Parameters Name Type Descriptionsampling_interval jint The sampling interval in bytes. The sampler uses a statistical approach to generate an event, on average, once for every sampling_interval bytes of memory allocated by a given thread. Once the new sampling interval is taken into account, 0 as a sampling interval will generate a sample for every allocation. Note: The overhead of this feature is directly correlated with the sampling interval. A high sampling interval, such as 1024 bytes, will incur a high overhead. A lower interval, such as 1024KB, will have a much lower overhead. Sampling should only be used with an understanding that it may impact performance. Errors Every JVM TI function returns a jvmtiError error code. It is the responsibility of the agent to call JVM TI functions with valid parameters and in the proper context (calling thread is attached, phase is correct, etc.). Detecting some error conditions may be difficult, inefficient, or impossible for an implementation. The errors listed in Function Specific Required Errors must be detected by the implementation. All other errors represent the recommended response to the error condition. Universal Errors The following errors may be returned by any function
JVMTI_ERROR_NONE (0)
JVMTI_ERROR_NULL_POINTER (100)
NULL.
JVMTI_ERROR_OUT_OF_MEMORY (110)
JVMTI_ERROR_ACCESS_DENIED (111)
JVMTI_ERROR_UNATTACHED_THREAD (115)
AttachCurrentThread in the JNI invocation API.
JVMTI_ERROR_INVALID_ENVIRONMENT (116)
JVMTI_ERROR_WRONG_PHASE (112)
JVMTI_ERROR_INTERNAL (113)
JVMTI_ERROR_INVALID_PRIORITY (12)
JVMTI_ERROR_THREAD_NOT_SUSPENDED (13)
JVMTI_ERROR_THREAD_SUSPENDED (14)
JVMTI_ERROR_THREAD_NOT_ALIVE (15)
JVMTI_ERROR_CLASS_NOT_PREPARED (22)
JVMTI_ERROR_NO_MORE_FRAMES (31)
JVMTI_ERROR_OPAQUE_FRAME (32)
JVMTI_ERROR_DUPLICATE (40)
JVMTI_ERROR_NOT_FOUND (41)
JVMTI_ERROR_NOT_MONITOR_OWNER (51)
JVMTI_ERROR_INTERRUPT (52)
JVMTI_ERROR_UNMODIFIABLE_CLASS (79)
JVMTI_ERROR_UNMODIFIABLE_MODULE (80)
JVMTI_ERROR_NOT_AVAILABLE (98)
JVMTI_ERROR_ABSENT_INFORMATION (101)
JVMTI_ERROR_INVALID_EVENT_TYPE (102)
JVMTI_ERROR_NATIVE_METHOD (104)
JVMTI_ERROR_CLASS_LOADER_UNSUPPORTED (106)
JVMTI_ERROR_INVALID_THREAD (10)
JVMTI_ERROR_INVALID_FIELDID (25)
JVMTI_ERROR_INVALID_MODULE (26)
JVMTI_ERROR_INVALID_METHODID (23)
JVMTI_ERROR_INVALID_LOCATION (24)
JVMTI_ERROR_INVALID_OBJECT (20)
JVMTI_ERROR_INVALID_CLASS (21)
JVMTI_ERROR_TYPE_MISMATCH (34)
JVMTI_ERROR_INVALID_SLOT (35)
JVMTI_ERROR_MUST_POSSESS_CAPABILITY (99)
JVMTI_ERROR_INVALID_THREAD_GROUP (11)
JVMTI_ERROR_INVALID_MONITOR (50)
JVMTI_ERROR_ILLEGAL_ARGUMENT (103)
JVMTI_ERROR_INVALID_TYPESTATE (65)
JVMTI_ERROR_UNSUPPORTED_VERSION (68)
JVMTI_ERROR_INVALID_CLASS_FORMAT (60)
ClassFormatError).
JVMTI_ERROR_CIRCULAR_CLASS_DEFINITION (61)
ClassCircularityError).
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_ADDED (63)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_SCHEMA_CHANGED (64)
JVMTI_ERROR_FAILS_VERIFICATION (62)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_HIERARCHY_CHANGED (66)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_DELETED (67)
JVMTI_ERROR_NAMES_DONT_MATCH (69)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_MODIFIERS_CHANGED (70)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_METHOD_MODIFIERS_CHANGED (71)
JVMTI_ERROR_UNSUPPORTED_REDEFINITION_CLASS_ATTRIBUTE_CHANGED (72)
JVMTI_ERROR_UNSUPPORTED_OPERATION (73)
jboolean
Holds a Java programming language
boolean
. Unsigned 8 bits.
jchar
Holds a Java programming language
char
. Unsigned 16 bits.
jint
Holds a Java programming language
int
. Signed 32 bits.
jlong
Holds a Java programming language
long
. Signed 64 bits.
jfloat
Holds a Java programming language
float
. 32 bits.
jdouble
Holds a Java programming language
double
. 64 bits.
jobject
Holds a Java programming language object.
jclass
Holds a Java programming language class.
jvalue
Is a union of all primitive types and
jobject
. Thus, holds any Java programming language value.
jfieldID
Identifies a Java programming language field.
jfieldID
s returned by JVM
TI functions and events may be safely stored.
jmethodID
Identifies a Java programming language method, initializer, or constructor.
jmethodID
s returned by JVM
TI functions and events may be safely stored. However, if the class is unloaded, they become invalid and must not be used.
JNIEnv
Pointer to the JNI function table. Pointer to this (
JNIEnv *
) is a JNI environment.
JVM Tool Interface Base Types Type DescriptionjvmtiEnv
The JVM
TI
environmentpointer. See the
Function Section.
jvmtiEnv
points to the
function tablepointer.
jthread
Subtype of
jobject
that holds a thread.
typedef jobject jthread;
jthreadGroup
Subtype of
jobject
that holds a thread group.
typedef jobject jthreadGroup;
jlocation
A 64 bit value, representing a monotonically increasing executable position within a method.
-1
indicates a native method. See
GetJLocationFormat
for the format on a given VM.
typedef jlong jlocation;
jrawMonitorID
A raw monitor.
struct _jrawMonitorID; typedef struct _jrawMonitorID *jrawMonitorID;
jvmtiError
Holds an error return code. See the
Error sectionfor possible values.
typedef enum {
JVMTI_ERROR_NONE = 0,
JVMTI_ERROR_INVALID_THREAD = 10,
...
} jvmtiError;
jvmtiEvent
An identifier for an event type. See the
Event sectionfor possible values. It is guaranteed that future versions of this specification will never assign zero as an event type identifier.
typedef enum {
JVMTI_EVENT_SINGLE_STEP = 1,
JVMTI_EVENT_BREAKPOINT = 2,
...
} jvmtiEvent;
jvmtiEventCallbacks
The callbacks used for events.
typedef struct {
jvmtiEventVMInit VMInit;
jvmtiEventVMDeath VMDeath;
...
} jvmtiEventCallbacks;
See
event callbacksfor the complete structure.
Where, for example, the VM initialization callback is defined:
typedef void (JNICALL *jvmtiEventVMInit)
(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread);
See the individual events for the callback function definition.
jniNativeInterface
Typedef for the JNI function table
JNINativeInterface
defined in the
JNI Specification. The JNI reference implementation defines this with an underscore.
typedef struct JNINativeInterface_ jniNativeInterface;Function Table Layout Position Function Declaration 1 reserved
void *reserved1;2 Set Event Notification Mode
jvmtiError (JNICALL *SetEventNotificationMode) (jvmtiEnv* env,
jvmtiEventMode mode,
jvmtiEvent event_type,
jthread event_thread,
...); 3 Get All Modules
jvmtiError (JNICALL *GetAllModules) (jvmtiEnv* env,
jint* module_count_ptr,
jobject** modules_ptr); 4 Get All Threads
jvmtiError (JNICALL *GetAllThreads) (jvmtiEnv* env,
jint* threads_count_ptr,
jthread** threads_ptr); 5 Suspend Thread
jvmtiError (JNICALL *SuspendThread) (jvmtiEnv* env,
jthread thread); 6 Resume Thread
jvmtiError (JNICALL *ResumeThread) (jvmtiEnv* env,
jthread thread); 7 Stop Thread
jvmtiError (JNICALL *StopThread) (jvmtiEnv* env,
jthread thread,
jobject exception); 8 Interrupt Thread
jvmtiError (JNICALL *InterruptThread) (jvmtiEnv* env,
jthread thread); 9 Get Thread Info
jvmtiError (JNICALL *GetThreadInfo) (jvmtiEnv* env,
jthread thread,
jvmtiThreadInfo* info_ptr); 10 Get Owned Monitor Info
jvmtiError (JNICALL *GetOwnedMonitorInfo) (jvmtiEnv* env,
jthread thread,
jint* owned_monitor_count_ptr,
jobject** owned_monitors_ptr); 11 Get Current Contended Monitor
jvmtiError (JNICALL *GetCurrentContendedMonitor) (jvmtiEnv* env,
jthread thread,
jobject* monitor_ptr); 12 Run Agent Thread
jvmtiError (JNICALL *RunAgentThread) (jvmtiEnv* env,
jthread thread,
jvmtiStartFunction proc,
const void* arg,
jint priority); 13 Get Top Thread Groups
jvmtiError (JNICALL *GetTopThreadGroups) (jvmtiEnv* env,
jint* group_count_ptr,
jthreadGroup** groups_ptr); 14 Get Thread Group Info
jvmtiError (JNICALL *GetThreadGroupInfo) (jvmtiEnv* env,
jthreadGroup group,
jvmtiThreadGroupInfo* info_ptr); 15 Get Thread Group Children
jvmtiError (JNICALL *GetThreadGroupChildren) (jvmtiEnv* env,
jthreadGroup group,
jint* thread_count_ptr,
jthread** threads_ptr,
jint* group_count_ptr,
jthreadGroup** groups_ptr); 16 Get Frame Count
jvmtiError (JNICALL *GetFrameCount) (jvmtiEnv* env,
jthread thread,
jint* count_ptr); 17 Get Thread State
jvmtiError (JNICALL *GetThreadState) (jvmtiEnv* env,
jthread thread,
jint* thread_state_ptr); 18 Get Current Thread
jvmtiError (JNICALL *GetCurrentThread) (jvmtiEnv* env,
jthread* thread_ptr); 19 Get Frame Location
jvmtiError (JNICALL *GetFrameLocation) (jvmtiEnv* env,
jthread thread,
jint depth,
jmethodID* method_ptr,
jlocation* location_ptr); 20 Notify Frame Pop
jvmtiError (JNICALL *NotifyFramePop) (jvmtiEnv* env,
jthread thread,
jint depth); 21 Get Local Variable - Object
jvmtiError (JNICALL *GetLocalObject) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jobject* value_ptr); 22 Get Local Variable - Int
jvmtiError (JNICALL *GetLocalInt) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jint* value_ptr); 23 Get Local Variable - Long
jvmtiError (JNICALL *GetLocalLong) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jlong* value_ptr); 24 Get Local Variable - Float
jvmtiError (JNICALL *GetLocalFloat) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jfloat* value_ptr); 25 Get Local Variable - Double
jvmtiError (JNICALL *GetLocalDouble) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jdouble* value_ptr); 26 Set Local Variable - Object
jvmtiError (JNICALL *SetLocalObject) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jobject value); 27 Set Local Variable - Int
jvmtiError (JNICALL *SetLocalInt) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jint value); 28 Set Local Variable - Long
jvmtiError (JNICALL *SetLocalLong) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jlong value); 29 Set Local Variable - Float
jvmtiError (JNICALL *SetLocalFloat) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jfloat value); 30 Set Local Variable - Double
jvmtiError (JNICALL *SetLocalDouble) (jvmtiEnv* env,
jthread thread,
jint depth,
jint slot,
jdouble value); 31 Create Raw Monitor
jvmtiError (JNICALL *CreateRawMonitor) (jvmtiEnv* env,
const char* name,
jrawMonitorID* monitor_ptr); 32 Destroy Raw Monitor
jvmtiError (JNICALL *DestroyRawMonitor) (jvmtiEnv* env,
jrawMonitorID monitor); 33 Raw Monitor Enter
jvmtiError (JNICALL *RawMonitorEnter) (jvmtiEnv* env,
jrawMonitorID monitor); 34 Raw Monitor Exit
jvmtiError (JNICALL *RawMonitorExit) (jvmtiEnv* env,
jrawMonitorID monitor); 35 Raw Monitor Wait
jvmtiError (JNICALL *RawMonitorWait) (jvmtiEnv* env,
jrawMonitorID monitor,
jlong millis); 36 Raw Monitor Notify
jvmtiError (JNICALL *RawMonitorNotify) (jvmtiEnv* env,
jrawMonitorID monitor); 37 Raw Monitor Notify All
jvmtiError (JNICALL *RawMonitorNotifyAll) (jvmtiEnv* env,
jrawMonitorID monitor); 38 Set Breakpoint
jvmtiError (JNICALL *SetBreakpoint) (jvmtiEnv* env,
jmethodID method,
jlocation location); 39 Clear Breakpoint
jvmtiError (JNICALL *ClearBreakpoint) (jvmtiEnv* env,
jmethodID method,
jlocation location); 40 Get Named Module
jvmtiError (JNICALL *GetNamedModule) (jvmtiEnv* env,
jobject class_loader,
const char* package_name,
jobject* module_ptr); 41 Set Field Access Watch
jvmtiError (JNICALL *SetFieldAccessWatch) (jvmtiEnv* env,
jclass klass,
jfieldID field); 42 Clear Field Access Watch
jvmtiError (JNICALL *ClearFieldAccessWatch) (jvmtiEnv* env,
jclass klass,
jfieldID field); 43 Set Field Modification Watch
jvmtiError (JNICALL *SetFieldModificationWatch) (jvmtiEnv* env,
jclass klass,
jfieldID field); 44 Clear Field Modification Watch
jvmtiError (JNICALL *ClearFieldModificationWatch) (jvmtiEnv* env,
jclass klass,
jfieldID field); 45 Is Modifiable Class
jvmtiError (JNICALL *IsModifiableClass) (jvmtiEnv* env,
jclass klass,
jboolean* is_modifiable_class_ptr); 46 Allocate
jvmtiError (JNICALL *Allocate) (jvmtiEnv* env,
jlong size,
unsigned char** mem_ptr); 47 Deallocate
jvmtiError (JNICALL *Deallocate) (jvmtiEnv* env,
unsigned char* mem); 48 Get Class Signature
jvmtiError (JNICALL *GetClassSignature) (jvmtiEnv* env,
jclass klass,
char** signature_ptr,
char** generic_ptr); 49 Get Class Status
jvmtiError (JNICALL *GetClassStatus) (jvmtiEnv* env,
jclass klass,
jint* status_ptr); 50 Get Source File Name
jvmtiError (JNICALL *GetSourceFileName) (jvmtiEnv* env,
jclass klass,
char** source_name_ptr); 51 Get Class Modifiers
jvmtiError (JNICALL *GetClassModifiers) (jvmtiEnv* env,
jclass klass,
jint* modifiers_ptr); 52 Get Class Methods
jvmtiError (JNICALL *GetClassMethods) (jvmtiEnv* env,
jclass klass,
jint* method_count_ptr,
jmethodID** methods_ptr); 53 Get Class Fields
jvmtiError (JNICALL *GetClassFields) (jvmtiEnv* env,
jclass klass,
jint* field_count_ptr,
jfieldID** fields_ptr); 54 Get Implemented Interfaces
jvmtiError (JNICALL *GetImplementedInterfaces) (jvmtiEnv* env,
jclass klass,
jint* interface_count_ptr,
jclass** interfaces_ptr); 55 Is Interface
jvmtiError (JNICALL *IsInterface) (jvmtiEnv* env,
jclass klass,
jboolean* is_interface_ptr); 56 Is Array Class
jvmtiError (JNICALL *IsArrayClass) (jvmtiEnv* env,
jclass klass,
jboolean* is_array_class_ptr); 57 Get Class Loader
jvmtiError (JNICALL *GetClassLoader) (jvmtiEnv* env,
jclass klass,
jobject* classloader_ptr); 58 Get Object Hash Code
jvmtiError (JNICALL *GetObjectHashCode) (jvmtiEnv* env,
jobject object,
jint* hash_code_ptr); 59 Get Object Monitor Usage
jvmtiError (JNICALL *GetObjectMonitorUsage) (jvmtiEnv* env,
jobject object,
jvmtiMonitorUsage* info_ptr); 60 Get Field Name (and Signature)
jvmtiError (JNICALL *GetFieldName) (jvmtiEnv* env,
jclass klass,
jfieldID field,
char** name_ptr,
char** signature_ptr,
char** generic_ptr); 61 Get Field Declaring Class
jvmtiError (JNICALL *GetFieldDeclaringClass) (jvmtiEnv* env,
jclass klass,
jfieldID field,
jclass* declaring_class_ptr); 62 Get Field Modifiers
jvmtiError (JNICALL *GetFieldModifiers) (jvmtiEnv* env,
jclass klass,
jfieldID field,
jint* modifiers_ptr); 63 Is Field Synthetic
jvmtiError (JNICALL *IsFieldSynthetic) (jvmtiEnv* env,
jclass klass,
jfieldID field,
jboolean* is_synthetic_ptr); 64 Get Method Name (and Signature)
jvmtiError (JNICALL *GetMethodName) (jvmtiEnv* env,
jmethodID method,
char** name_ptr,
char** signature_ptr,
char** generic_ptr); 65 Get Method Declaring Class
jvmtiError (JNICALL *GetMethodDeclaringClass) (jvmtiEnv* env,
jmethodID method,
jclass* declaring_class_ptr); 66 Get Method Modifiers
jvmtiError (JNICALL *GetMethodModifiers) (jvmtiEnv* env,
jmethodID method,
jint* modifiers_ptr); 67 reserved
void *reserved67;68 Get Max Locals
jvmtiError (JNICALL *GetMaxLocals) (jvmtiEnv* env,
jmethodID method,
jint* max_ptr); 69 Get Arguments Size
jvmtiError (JNICALL *GetArgumentsSize) (jvmtiEnv* env,
jmethodID method,
jint* size_ptr); 70 Get Line Number Table
jvmtiError (JNICALL *GetLineNumberTable) (jvmtiEnv* env,
jmethodID method,
jint* entry_count_ptr,
jvmtiLineNumberEntry** table_ptr); 71 Get Method Location
jvmtiError (JNICALL *GetMethodLocation) (jvmtiEnv* env,
jmethodID method,
jlocation* start_location_ptr,
jlocation* end_location_ptr); 72 Get Local Variable Table
jvmtiError (JNICALL *GetLocalVariableTable) (jvmtiEnv* env,
jmethodID method,
jint* entry_count_ptr,
jvmtiLocalVariableEntry** table_ptr); 73 Set Native Method Prefix
jvmtiError (JNICALL *SetNativeMethodPrefix) (jvmtiEnv* env,
const char* prefix); 74 Set Native Method Prefixes
jvmtiError (JNICALL *SetNativeMethodPrefixes) (jvmtiEnv* env,
jint prefix_count,
char** prefixes); 75 Get Bytecodes
jvmtiError (JNICALL *GetBytecodes) (jvmtiEnv* env,
jmethodID method,
jint* bytecode_count_ptr,
unsigned char** bytecodes_ptr); 76 Is Method Native
jvmtiError (JNICALL *IsMethodNative) (jvmtiEnv* env,
jmethodID method,
jboolean* is_native_ptr); 77 Is Method Synthetic
jvmtiError (JNICALL *IsMethodSynthetic) (jvmtiEnv* env,
jmethodID method,
jboolean* is_synthetic_ptr); 78 Get Loaded Classes
jvmtiError (JNICALL *GetLoadedClasses) (jvmtiEnv* env,
jint* class_count_ptr,
jclass** classes_ptr); 79 Get Classloader Classes
jvmtiError (JNICALL *GetClassLoaderClasses) (jvmtiEnv* env,
jobject initiating_loader,
jint* class_count_ptr,
jclass** classes_ptr); 80 Pop Frame
jvmtiError (JNICALL *PopFrame) (jvmtiEnv* env,
jthread thread); 81 Force Early Return - Object
jvmtiError (JNICALL *ForceEarlyReturnObject) (jvmtiEnv* env,
jthread thread,
jobject value); 82 Force Early Return - Int
jvmtiError (JNICALL *ForceEarlyReturnInt) (jvmtiEnv* env,
jthread thread,
jint value); 83 Force Early Return - Long
jvmtiError (JNICALL *ForceEarlyReturnLong) (jvmtiEnv* env,
jthread thread,
jlong value); 84 Force Early Return - Float
jvmtiError (JNICALL *ForceEarlyReturnFloat) (jvmtiEnv* env,
jthread thread,
jfloat value); 85 Force Early Return - Double
jvmtiError (JNICALL *ForceEarlyReturnDouble) (jvmtiEnv* env,
jthread thread,
jdouble value); 86 Force Early Return - Void
jvmtiError (JNICALL *ForceEarlyReturnVoid) (jvmtiEnv* env,
jthread thread); 87 Redefine Classes
jvmtiError (JNICALL *RedefineClasses) (jvmtiEnv* env,
jint class_count,
const jvmtiClassDefinition* class_definitions); 88 Get Version Number
jvmtiError (JNICALL *GetVersionNumber) (jvmtiEnv* env,
jint* version_ptr); 89 Get Capabilities
jvmtiError (JNICALL *GetCapabilities) (jvmtiEnv* env,
jvmtiCapabilities* capabilities_ptr); 90 Get Source Debug Extension
jvmtiError (JNICALL *GetSourceDebugExtension) (jvmtiEnv* env,
jclass klass,
char** source_debug_extension_ptr); 91 Is Method Obsolete
jvmtiError (JNICALL *IsMethodObsolete) (jvmtiEnv* env,
jmethodID method,
jboolean* is_obsolete_ptr); 92 Suspend Thread List
jvmtiError (JNICALL *SuspendThreadList) (jvmtiEnv* env,
jint request_count,
const jthread* request_list,
jvmtiError* results); 93 Resume Thread List
jvmtiError (JNICALL *ResumeThreadList) (jvmtiEnv* env,
jint request_count,
const jthread* request_list,
jvmtiError* results); 94 Add Module Reads
jvmtiError (JNICALL *AddModuleReads) (jvmtiEnv* env,
jobject module,
jobject to_module); 95 Add Module Exports
jvmtiError (JNICALL *AddModuleExports) (jvmtiEnv* env,
jobject module,
const char* pkg_name,
jobject to_module); 96 Add Module Opens
jvmtiError (JNICALL *AddModuleOpens) (jvmtiEnv* env,
jobject module,
const char* pkg_name,
jobject to_module); 97 Add Module Uses
jvmtiError (JNICALL *AddModuleUses) (jvmtiEnv* env,
jobject module,
jclass service); 98 Add Module Provides
jvmtiError (JNICALL *AddModuleProvides) (jvmtiEnv* env,
jobject module,
jclass service,
jclass impl_class); 99 Is Modifiable Module
jvmtiError (JNICALL *IsModifiableModule) (jvmtiEnv* env,
jobject module,
jboolean* is_modifiable_module_ptr); 100 Get All Stack Traces
jvmtiError (JNICALL *GetAllStackTraces) (jvmtiEnv* env,
jint max_frame_count,
jvmtiStackInfo** stack_info_ptr,
jint* thread_count_ptr); 101 Get Thread List Stack Traces
jvmtiError (JNICALL *GetThreadListStackTraces) (jvmtiEnv* env,
jint thread_count,
const jthread* thread_list,
jint max_frame_count,
jvmtiStackInfo** stack_info_ptr); 102 Get Thread Local Storage
jvmtiError (JNICALL *GetThreadLocalStorage) (jvmtiEnv* env,
jthread thread,
void** data_ptr); 103 Set Thread Local Storage
jvmtiError (JNICALL *SetThreadLocalStorage) (jvmtiEnv* env,
jthread thread,
const void* data); 104 Get Stack Trace
jvmtiError (JNICALL *GetStackTrace) (jvmtiEnv* env,
jthread thread,
jint start_depth,
jint max_frame_count,
jvmtiFrameInfo* frame_buffer,
jint* count_ptr); 105 reserved
void *reserved105;106 Get Tag
jvmtiError (JNICALL *GetTag) (jvmtiEnv* env,
jobject object,
jlong* tag_ptr); 107 Set Tag
jvmtiError (JNICALL *SetTag) (jvmtiEnv* env,
jobject object,
jlong tag); 108 Force Garbage Collection
jvmtiError (JNICALL *ForceGarbageCollection) (jvmtiEnv* env);109 Iterate Over Objects Reachable From Object
jvmtiError (JNICALL *IterateOverObjectsReachableFromObject) (jvmtiEnv* env,
jobject object,
jvmtiObjectReferenceCallback object_reference_callback,
const void* user_data); 110 Iterate Over Reachable Objects
jvmtiError (JNICALL *IterateOverReachableObjects) (jvmtiEnv* env,
jvmtiHeapRootCallback heap_root_callback,
jvmtiStackReferenceCallback stack_ref_callback,
jvmtiObjectReferenceCallback object_ref_callback,
const void* user_data); 111 Iterate Over Heap
jvmtiError (JNICALL *IterateOverHeap) (jvmtiEnv* env,
jvmtiHeapObjectFilter object_filter,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data); 112 Iterate Over Instances Of Class
jvmtiError (JNICALL *IterateOverInstancesOfClass) (jvmtiEnv* env,
jclass klass,
jvmtiHeapObjectFilter object_filter,
jvmtiHeapObjectCallback heap_object_callback,
const void* user_data); 113 reserved
void *reserved113;114 Get Objects With Tags
jvmtiError (JNICALL *GetObjectsWithTags) (jvmtiEnv* env,
jint tag_count,
const jlong* tags,
jint* count_ptr,
jobject** object_result_ptr,
jlong** tag_result_ptr); 115 Follow References
jvmtiError (JNICALL *FollowReferences) (jvmtiEnv* env,
jint heap_filter,
jclass klass,
jobject initial_object,
const jvmtiHeapCallbacks* callbacks,
const void* user_data); 116 Iterate Through Heap
jvmtiError (JNICALL *IterateThroughHeap) (jvmtiEnv* env,
jint heap_filter,
jclass klass,
const jvmtiHeapCallbacks* callbacks,
const void* user_data); 117 reserved
void *reserved117;118 Suspend All Virtual Threads
jvmtiError (JNICALL *SuspendAllVirtualThreads) (jvmtiEnv* env,
jint except_count,
const jthread* except_list); 119 Resume All Virtual Threads
jvmtiError (JNICALL *ResumeAllVirtualThreads) (jvmtiEnv* env,
jint except_count,
const jthread* except_list); 120 Set JNI Function Table
jvmtiError (JNICALL *SetJNIFunctionTable) (jvmtiEnv* env,
const jniNativeInterface* function_table); 121 Get JNI Function Table
jvmtiError (JNICALL *GetJNIFunctionTable) (jvmtiEnv* env,
jniNativeInterface** function_table); 122 Set Event Callbacks
jvmtiError (JNICALL *SetEventCallbacks) (jvmtiEnv* env,
const jvmtiEventCallbacks* callbacks,
jint size_of_callbacks); 123 Generate Events
jvmtiError (JNICALL *GenerateEvents) (jvmtiEnv* env,
jvmtiEvent event_type); 124 Get Extension Functions
jvmtiError (JNICALL *GetExtensionFunctions) (jvmtiEnv* env,
jint* extension_count_ptr,
jvmtiExtensionFunctionInfo** extensions); 125 Get Extension Events
jvmtiError (JNICALL *GetExtensionEvents) (jvmtiEnv* env,
jint* extension_count_ptr,
jvmtiExtensionEventInfo** extensions); 126 Set Extension Event Callback
jvmtiError (JNICALL *SetExtensionEventCallback) (jvmtiEnv* env,
jint extension_event_index,
jvmtiExtensionEvent callback); 127 Dispose Environment
jvmtiError (JNICALL *DisposeEnvironment) (jvmtiEnv* env);128 Get Error Name
jvmtiError (JNICALL *GetErrorName) (jvmtiEnv* env,
jvmtiError error,
char** name_ptr); 129 Get JLocation Format
jvmtiError (JNICALL *GetJLocationFormat) (jvmtiEnv* env,
jvmtiJlocationFormat* format_ptr); 130 Get System Properties
jvmtiError (JNICALL *GetSystemProperties) (jvmtiEnv* env,
jint* count_ptr,
char*** property_ptr); 131 Get System Property
jvmtiError (JNICALL *GetSystemProperty) (jvmtiEnv* env,
const char* property,
char** value_ptr); 132 Set System Property
jvmtiError (JNICALL *SetSystemProperty) (jvmtiEnv* env,
const char* property,
const char* value_ptr); 133 Get Phase
jvmtiError (JNICALL *GetPhase) (jvmtiEnv* env,
jvmtiPhase* phase_ptr); 134 Get Current Thread CPU Timer Information
jvmtiError (JNICALL *GetCurrentThreadCpuTimerInfo) (jvmtiEnv* env,
jvmtiTimerInfo* info_ptr); 135 Get Current Thread CPU Time
jvmtiError (JNICALL *GetCurrentThreadCpuTime) (jvmtiEnv* env,
jlong* nanos_ptr); 136 Get Thread CPU Timer Information
jvmtiError (JNICALL *GetThreadCpuTimerInfo) (jvmtiEnv* env,
jvmtiTimerInfo* info_ptr); 137 Get Thread CPU Time
jvmtiError (JNICALL *GetThreadCpuTime) (jvmtiEnv* env,
jthread thread,
jlong* nanos_ptr); 138 Get Timer Information
jvmtiError (JNICALL *GetTimerInfo) (jvmtiEnv* env,
jvmtiTimerInfo* info_ptr); 139 Get Time
jvmtiError (JNICALL *GetTime) (jvmtiEnv* env,
jlong* nanos_ptr); 140 Get Potential Capabilities
jvmtiError (JNICALL *GetPotentialCapabilities) (jvmtiEnv* env,
jvmtiCapabilities* capabilities_ptr); 141 reserved
void *reserved141;142 Add Capabilities
jvmtiError (JNICALL *AddCapabilities) (jvmtiEnv* env,
const jvmtiCapabilities* capabilities_ptr); 143 Relinquish Capabilities
jvmtiError (JNICALL *RelinquishCapabilities) (jvmtiEnv* env,
const jvmtiCapabilities* capabilities_ptr); 144 Get Available Processors
jvmtiError (JNICALL *GetAvailableProcessors) (jvmtiEnv* env,
jint* processor_count_ptr); 145 Get Class Version Numbers
jvmtiError (JNICALL *GetClassVersionNumbers) (jvmtiEnv* env,
jclass klass,
jint* minor_version_ptr,
jint* major_version_ptr); 146 Get Constant Pool
jvmtiError (JNICALL *GetConstantPool) (jvmtiEnv* env,
jclass klass,
jint* constant_pool_count_ptr,
jint* constant_pool_byte_count_ptr,
unsigned char** constant_pool_bytes_ptr); 147 Get Environment Local Storage
jvmtiError (JNICALL *GetEnvironmentLocalStorage) (jvmtiEnv* env,
void** data_ptr); 148 Set Environment Local Storage
jvmtiError (JNICALL *SetEnvironmentLocalStorage) (jvmtiEnv* env,
const void* data); 149 Add To Bootstrap Class Loader Search
jvmtiError (JNICALL *AddToBootstrapClassLoaderSearch) (jvmtiEnv* env,
const char* segment); 150 Set Verbose Flag
jvmtiError (JNICALL *SetVerboseFlag) (jvmtiEnv* env,
jvmtiVerboseFlag flag,
jboolean value); 151 Add To System Class Loader Search
jvmtiError (JNICALL *AddToSystemClassLoaderSearch) (jvmtiEnv* env,
const char* segment); 152 Retransform Classes
jvmtiError (JNICALL *RetransformClasses) (jvmtiEnv* env,
jint class_count,
const jclass* classes); 153 Get Owned Monitor Stack Depth Info
jvmtiError (JNICALL *GetOwnedMonitorStackDepthInfo) (jvmtiEnv* env,
jthread thread,
jint* monitor_info_count_ptr,
jvmtiMonitorStackDepthInfo** monitor_info_ptr); 154 Get Object Size
jvmtiError (JNICALL *GetObjectSize) (jvmtiEnv* env,
jobject object,
jlong* size_ptr); 155 Get Local Instance
jvmtiError (JNICALL *GetLocalInstance) (jvmtiEnv* env,
jthread thread,
jint depth,
jobject* value_ptr); 156 Set Heap Sampling Interval
jvmtiError (JNICALL *SetHeapSamplingInterval) (jvmtiEnv* env,
jint sampling_interval); Events Handling Events Agents can be informed of many events that occur in application programs. To handle events, designate a set of callback functions with SetEventCallbacks. For each event the corresponding callback function will be called. Arguments to the callback function provide additional information about the event. The callback function is usually called from within an application thread. The JVM TI implementation does not queue events in any way. This means that event callback functions must be written carefully. Here are some general guidelines. See the individual event descriptions for further suggestions.
SuspendThread. If an event is enabled in multiple environments, the event will be sent to each agent in the order that the environments were created. Enabling Events All events are initially disabled. In order to receive any event:
AddCapabilities.SetEventCallbacks.SetEventNotificationMode.MethodEntry event is reported before any other event at the current location in the same thread. If an exception catch has been detected at the current location, either because it is the beginning of a catch clause or a native method that cleared a pending exception has returned, the exceptionCatch event is reported before any other event at the current location in the same thread. If a singleStep event or breakpoint event is triggered at the current location, the event is defined to occur immediately before the code at the current location is executed. These events are reported before any events which are triggered by the execution of code at the current location in the same thread (specifically: exception, fieldAccess, and fieldModification). If both a step and breakpoint event are triggered for the same thread and location, the step event is reported before the breakpoint event. If the current location is the exit point of a method (that is, the last location before returning to the caller), the MethodExit event and the FramePop event (if requested) are reported after all other events at the current location in the same thread. There is no specified ordering of these two events with respect to each other. Co-located events can be triggered during the processing of some other event by the agent at the same location in the same thread. If such an event, of type y, is triggered during the processing of an event of type x, and if x precedes y in the ordering specified above, the co-located event y is reported for the current thread and location. If x does not precede y, y is not reported for the current thread and location. For example, if a breakpoint is set at the current location during the processing of SingleStep, that breakpoint will be reported before the thread moves off the current location. The following events are never considered to be co-located with other events.
Event Callbacks The event callback structure below is used to specify the handler function for events. It is set with the SetEventCallbacks function.
typedef struct {
jvmtiEventVMInit VMInit;
jvmtiEventVMDeath VMDeath;
jvmtiEventThreadStart ThreadStart;
jvmtiEventThreadEnd ThreadEnd;
jvmtiEventClassFileLoadHook ClassFileLoadHook;
jvmtiEventClassLoad ClassLoad;
jvmtiEventClassPrepare ClassPrepare;
jvmtiEventVMStart VMStart;
jvmtiEventException Exception;
jvmtiEventExceptionCatch ExceptionCatch;
jvmtiEventSingleStep SingleStep;
jvmtiEventFramePop FramePop;
jvmtiEventBreakpoint Breakpoint;
jvmtiEventFieldAccess FieldAccess;
jvmtiEventFieldModification FieldModification;
jvmtiEventMethodEntry MethodEntry;
jvmtiEventMethodExit MethodExit;
jvmtiEventNativeMethodBind NativeMethodBind;
jvmtiEventCompiledMethodLoad CompiledMethodLoad;
jvmtiEventCompiledMethodUnload CompiledMethodUnload;
jvmtiEventDynamicCodeGenerated DynamicCodeGenerated;
jvmtiEventDataDumpRequest DataDumpRequest;
jvmtiEventReserved reserved72;
jvmtiEventMonitorWait MonitorWait;
jvmtiEventMonitorWaited MonitorWaited;
jvmtiEventMonitorContendedEnter MonitorContendedEnter;
jvmtiEventMonitorContendedEntered MonitorContendedEntered;
jvmtiEventReserved reserved77;
jvmtiEventReserved reserved78;
jvmtiEventReserved reserved79;
jvmtiEventResourceExhausted ResourceExhausted;
jvmtiEventGarbageCollectionStart GarbageCollectionStart;
jvmtiEventGarbageCollectionFinish GarbageCollectionFinish;
jvmtiEventObjectFree ObjectFree;
jvmtiEventVMObjectAlloc VMObjectAlloc;
jvmtiEventReserved reserved85;
jvmtiEventSampledObjectAlloc SampledObjectAlloc;
jvmtiEventVirtualThreadStart VirtualThreadStart;
jvmtiEventVirtualThreadEnd VirtualThreadEnd;
} jvmtiEventCallbacks;
Event Index
void JNICALL
SingleStep(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location)
Single step events allow the agent to trace thread execution at the finest granularity allowed by the VM. A single step event is generated whenever a thread reaches a new location. Typically, single step events represent the completion of one VM instruction as defined in The Java™ Virtual Machine Specification. However, some implementations may define locations differently. In any case the method and location parameters uniquely identify the current location and allow the mapping to source file and line number when that information is available. No single step events are generated from within native methods.
sent only during the live phase
JVMTI_EVENT_SINGLE_STEP
60
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread about to execution a new instruction method jmethodID Method about to execute a new instruction location jlocation Location of the new instruction Breakpoint
void JNICALL
Breakpoint(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location)
Breakpoint events are generated whenever a thread reaches a location designated as a breakpoint with SetBreakpoint. The method and location parameters uniquely identify the current location and allow the mapping to source file and line number when that information is available.
sent only during the live phase
JVMTI_EVENT_BREAKPOINT
62
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. thread jthread Thread that hit the breakpoint method jmethodID Method that hit the breakpoint location jlocation location of the breakpoint Field Access
void JNICALL
FieldAccess(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location,
jclass field_klass,
jobject object,
jfieldID field)
Field access events are generated whenever a thread accesses a field that was designated as a watchpoint with SetFieldAccessWatch. The method and location parameters uniquely identify the current location and allow the mapping to source file and line number when that information is available.
sent only during the live phase
JVMTI_EVENT_FIELD_ACCESS
63
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread accessing the field method jmethodID Method where the access is occurring location jlocation Location where the access is occurring field_klass jclass Class of the field being accessed object jobject Object with the field being accessed if the field is an instance field; NULL otherwise field jfieldID Field being accessed Field Modification
void JNICALL
FieldModification(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location,
jclass field_klass,
jobject object,
jfieldID field,
char signature_type,
jvalue new_value)
Field modification events are generated whenever a thread modifies a field that was designated as a watchpoint with SetFieldModificationWatch. The method and location parameters uniquely identify the current location and allow the mapping to source file and line number when that information is available.
sent only during the live phase
JVMTI_EVENT_FIELD_MODIFICATION
64
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread modifying the field method jmethodID Method where the modification is occurring location jlocation Location where the modification is occurring field_klass jclass Class of the field being modified object jobject Object with the field being modified if the field is an instance field; NULL otherwise field jfieldID Field being modified signature_type char Signature type of the new value new_value jvalue The new value Frame Pop
void JNICALL
FramePop(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jboolean was_popped_by_exception)
Frame pop events are generated upon exit from a single method in a single frame as specified in a call to NotifyFramePop. This is true whether termination is caused by executing its return instruction or by throwing an exception to its caller (see was_popped_by_exception). However, frame pops caused by the PopFrame function are not reported. The location reported by GetFrameLocation for the depth 0 identifies the executable location in the returning method, immediately prior to the return.
sent only during the live phase
JVMTI_EVENT_FRAME_POP
61
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread that is popping the frame method jmethodID Method being popped was_popped_by_exception jboolean True if frame was popped by a thrown exception. False if method exited through its return instruction. Method Entry
void JNICALL
MethodEntry(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method)
Method entry events are generated upon entry of Java programming language methods (including native methods). The location reported by GetFrameLocation for the depth 0 identifies the initial executable location in the method. Enabling method entry or exit events will significantly degrade performance on many platforms and is thus not advised for performance critical usage (such as profiling). Bytecode instrumentation should be used in these cases.
sent only during the live phase
JVMTI_EVENT_METHOD_ENTRY
65
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_method_entry_events Can generate method entry events on entering a method Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread entering the method method jmethodID Method being entered Method Exit
void JNICALL
MethodExit(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jboolean was_popped_by_exception,
jvalue return_value)
Method exit events are generated upon exit from Java programming language methods (including native methods). This is true whether termination is caused by executing its return instruction or by throwing an exception to its caller (see was_popped_by_exception). The location reported by GetFrameLocation for the depth 0 identifies the executable location in the returning method immediately prior to the return. Enabling method entry or exit events will significantly degrade performance on many platforms and is thus not advised for performance critical usage (such as profiling). Bytecode instrumentation should be used in these cases.
sent only during the live phase
JVMTI_EVENT_METHOD_EXIT
66
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_method_exit_events Can generate method exit events on leaving a method Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread exiting the method method jmethodID Method being exited was_popped_by_exception jboolean True if frame was popped by a thrown exception. False if method exited through its return instruction. return_value jvalue The return value of the method being exited. Undefined and should not be used if was_popped_by_exception is true. Native Method Bind
void JNICALL
NativeMethodBind(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
void* address,
void** new_address_ptr)
A Native Method Bind event is sent when a VM binds a Java programming language native method to the address of a function that implements the native method. This will occur when the native method is called for the first time and also occurs when the JNI function RegisterNatives is called. This event allows the bind to be redirected to an agent-specified proxy function. This event is not sent when the native method is unbound. Typically, this proxy function will need to be specific to a particular method or, to handle the general case, automatically generated assembly code, since after instrumentation code is executed the function at the original binding address will usually be invoked. The original binding can be restored or the redirection changed by use of the JNI function RegisterNatives. Some events may be sent during the primordial phase, JNI and most of JVM TI cannot be used at this time but the method and address can be saved for use later.
sent during the primordial, start or live phase
JVMTI_EVENT_NATIVE_METHOD_BIND
67
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_native_method_bind_events Can generate events when a native method is bound to its implementation Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread Will be NULL if sent during the primordial phase. thread jthread Thread requesting the bind method jmethodID Native method being bound address void* The address the VM is about to bind to--that is, the address of the implementation of the native method new_address_ptr void** if the referenced address is changed (that is, if *new_address_ptr is set), the binding will instead be made to the supplied address. Exception
void JNICALL
Exception(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location,
jobject exception,
jmethodID catch_method,
jlocation catch_location)
Exception events are generated whenever an exception is first detected in a Java programming language method. Where "exception" means any java.lang.Throwable. The exception may have been thrown by a Java programming language or native method, but in the case of native methods, the event is not generated until the exception is first seen by a Java programming language method. If an exception is set and cleared in a native method (and thus is never visible to Java programming language code), no exception event is generated. The method and location parameters uniquely identify the current location (where the exception was detected) and allow the mapping to source file and line number when that information is available. The exception field identifies the thrown exception object. The catch_method and catch_location identify the location of the catch clause, if any, that handles the thrown exception. If there is no such catch clause, each field is set to 0. There is no guarantee that the thread will ever reach this catch clause. If there are native methods on the call stack between the throw location and the catch clause, the exception may be reset by one of those native methods. Similarly, exceptions that are reported as uncaught (catch_klass et al. set to 0) may in fact be caught by native code. Agents can check for these occurrences by monitoring ExceptionCatch events. Note that finally clauses are implemented as catch and re-throw. Therefore they will be reported in the catch location.
sent only during the live phase
JVMTI_EVENT_EXCEPTION
58
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread generating the exception method jmethodID Method generating the exception location jlocation Location where exception occurred exception jobject The exception being thrown catch_method jmethodID Method that will catch the exception, or NULL if no known catch catch_location jlocation location which will catch the exception or zero if no known catch Exception Catch
void JNICALL
ExceptionCatch(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jmethodID method,
jlocation location,
jobject exception)
Exception catch events are generated whenever a thrown exception is caught. Where "exception" means any java.lang.Throwable. If the exception is caught in a Java programming language method, the event is generated when the catch clause is reached. If the exception is caught in a native method, the event is generated as soon as control is returned to a Java programming language method. Exception catch events are generated for any exception for which a throw was detected in a Java programming language method. Note that finally clauses are implemented as catch and re-throw. Therefore they will generate exception catch events. The method and location parameters uniquely identify the current location and allow the mapping to source file and line number when that information is available. For exceptions caught in a Java programming language method, the exception object identifies the exception object. Exceptions caught in native methods are not necessarily available by the time the exception catch is reported, so the exception field is set to NULL.
sent only during the live phase
JVMTI_EVENT_EXCEPTION_CATCH
59
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread catching the exception method jmethodID Method catching the exception location jlocation Location where exception is being caught exception jobject Exception being caught Thread Start
void JNICALL
ThreadStart(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread)
A thread start event is generated by a new thread before its initial method executes. This event is generated by platform threads. It is also generated by virtual threads when the capability can_support_virtual_threads is not enabled. Agents without support for virtual threads that enable this event will therefore be notified by all newly started threads. If the capability can_support_virtual_threads is enabled then this event is not generated by virtual threads. Agents with support for virtual threads can enable VirtualThreadStart to be notified by newly started virtual threads. A platform thread may be listed in the array returned by GetAllThreads before its thread start event is generated. It is possible for other events to be generated on a thread before its thread start event. The event is sent on the newly started thread.
sent during the start or live phase
JVMTI_EVENT_THREAD_START
52
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. thread jthread Thread starting Thread End
void JNICALL
ThreadEnd(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread)
A thread end event is generated by a terminating thread after its initial method has finished execution. This event is generated by platform threads. It is also generated by virtual threads when the capability can_support_virtual_threads is not enabled. Agents without support for virtual threads that enable this event for all threads will therefore be notified by all terminating threads. If the capability can_support_virtual_threads is enabled then this event is not generated by virtual threads. Agents with support for virtual threads can enable VirtualThreadEnd to be notified by terminating virtual threads. A platform thread may be listed in the array returned by GetAllThreads after its thread end event is generated. No events are generated on a thread after its thread end event. The event is sent on the terminating thread.
sent during the start or live phase
JVMTI_EVENT_THREAD_END
53
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. thread jthread Thread ending Virtual Thread Start
void JNICALL
VirtualThreadStart(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread virtual_thread)
VirtualThreadStart is a preview API of the Java platform. Preview features may be removed in a future release, or upgraded to permanent features of the Java platform. A virtual thread start event is generated before its initial method executes. The event is sent on the newly started virtual_thread.
sent during the start or live phase
JVMTI_EVENT_VIRTUAL_THREAD_START
87
19
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_support_virtual_threads Can support virtual threads Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread. virtual_thread jthread Virtual thread started for execution. Virtual Thread End
void JNICALL
VirtualThreadEnd(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread virtual_thread)
VirtualThreadEnd is a preview API of the Java platform. Preview features may be removed in a future release, or upgraded to permanent features of the Java platform. A virtual thread end event is generated after its initial method has finished execution. The event is sent on the terminating virtual_thread.
sent during the start or live phase
JVMTI_EVENT_VIRTUAL_THREAD_END
88
19
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_support_virtual_threads Can support virtual threads Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread. virtual_thread jthread Virtual thread being ended. Class Load
void JNICALL
ClassLoad(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jclass klass)
A class load event is generated when a class or interface is created.. Array class creation does not generate a class load event. The creation of a primitive class (for example, java.lang.Integer.TYPE) does not generate a class load event. The order of class load events generated by a particular thread is guaranteed to match the order of class loading within that thread. This event is sent at an early stage in loading the class. As a result the class should be used carefully. Note, for example, that methods and fields are not yet loaded, so queries for methods, fields, subclasses, and so on will not give correct results. See "Loading of Classes and Interfaces" in the Java Language Specification. For most purposes the ClassPrepare event will be more useful.
sent during the start or live phase
JVMTI_EVENT_CLASS_LOAD
55
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread loading the class klass jclass Class being loaded Class Prepare
void JNICALL
ClassPrepare(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jclass klass)
A class prepare event is generated when class preparation is complete. At this point, class fields, methods, and implemented interfaces are available, and no code from the class has been executed. Since array classes never have fields or methods, class prepare events are not generated for them. Class prepare events are not generated for primitive classes (for example, java.lang.Integer.TYPE).
sent during the start or live phase
JVMTI_EVENT_CLASS_PREPARE
56
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread generating the class prepare klass jclass Class being prepared Class File Load Hook
void JNICALL
ClassFileLoadHook(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jclass class_being_redefined,
jobject loader,
const char* name,
jobject protection_domain,
jint class_data_len,
const unsigned char* class_data,
jint* new_class_data_len,
unsigned char** new_class_data)
This event is sent when the VM obtains class file data, but before it constructs the in-memory representation for that class. This event is also sent when the class is being modified by the RetransformClasses function or the RedefineClasses function, called in any JVM TI environment. The agent can instrument the existing class file data sent by the VM to include profiling/debugging hooks. See the description of bytecode instrumentation for usage information. When the capabilities can_generate_early_class_hook_events and can_generate_all_class_hook_events are enabled then this event may be sent in the primordial phase. Otherwise, this event may be sent before the VM is initialized (the start phase). Some classes might not be compatible with the function (eg. ROMized classes or implementation defined classes) and this event will not be generated for these classes. The agent must allocate the space for the modified class file data buffer using the memory allocation function Allocate because the VM is responsible for freeing the new class file data buffer using Deallocate. If the agent wishes to modify the class file, it must set new_class_data to point to the newly instrumented class file data buffer and set new_class_data_len to the length of that buffer before returning from this call. If no modification is desired, the agent simply does not set new_class_data. If multiple agents have enabled this event the results are chained. That is, if new_class_data has been set, it becomes the class_data for the next agent. When handling a class load in the live phase, then the GetNamedModule function can be used to map class loader and a package name to a module. When a class is being redefined or retransformed then class_being_redefined is non NULL and so the JNI GetModule function can also be used to obtain the Module. The order that this event is sent to each environment differs from other events. This event is sent to environments in the following order:
RetransformClasses, this event is sent only to retransformation capable environments.
sent during the primordial, start or live phase
JVMTI_EVENT_CLASS_FILE_LOAD_HOOK
54
1.0
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. class_being_redefined jclass The class being redefined or retransformed. NULL if sent by class load. loader jobject The class loader loading the class. NULL if the bootstrap class loader. name const char* Name of class being loaded as a VM internal qualified name (for example, "java/util/List"), encoded as a modified UTF-8 string. Note: if the class is defined with a NULL name or without a name specified, name will be NULL. protection_domain jobject The ProtectionDomain of the class. class_data_len jint Length of current class file data buffer. class_data const unsigned char* Pointer to the current class file data buffer. new_class_data_len jint* Pointer to the length of the new class file data buffer. new_class_data unsigned char** Pointer to the pointer to the instrumented class file data buffer. VM Start Event
void JNICALL
VMStart(jvmtiEnv *jvmti_env,
JNIEnv* jni_env)
The VM start event signals the start of the VM. At this time JNI is live but the VM is not yet fully initialized. Once this event is generated, the agent is free to call any JNI function. This event signals the beginning of the start phase, JVM TI functions permitted in the start phase may be called. The timing of this event may depend on whether the agent has added the can_generate_early_vmstart capability or not. If the capability has been added then the VM posts the event as early as possible. The VM is capable of executing bytecode but it may not have initialized to the point where it can load classes in modules other than java.base, or even arbitrary classes in java.base. Agents that do load-time instrumentation in this phase must take great care when instrumenting code that potentially executes in this phase. Extreme care should also be taken with JNI FindClass as it may not be possible to load classes and attempts to do so may result in unpredictable behavior, maybe even stability issues on some VM implementations. If the capability has not been added then the VM delays posting this event until it is capable of loading classes in modules other than java.base or the VM has completed its initialization. Agents that create more than one JVM TI environment, where the capability is added to some but not all environments, may observe the start phase beginning earlier in the JVM TI environments that possess the capability. In the case of VM start-up failure, this event will not be sent.
sent during the start or live phase
JVMTI_EVENT_VM_START
57
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. VM Initialization Event
void JNICALL
VMInit(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread)
The VM initialization event signals the completion of VM initialization. Once this event is generated, the agent is free to call any JNI or JVM TI function. The VM initialization event can be preceded by or can be concurrent with other events, but the preceding events should be handled carefully, if at all, because the VM has not completed its initialization. The thread start event for the main application thread is guaranteed not to occur until after the handler for the VM initialization event returns. In the case of VM start-up failure, this event will not be sent.
sent only during the live phase
JVMTI_EVENT_VM_INIT
50
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. thread jthread The initial thread VM Death Event
void JNICALL
VMDeath(jvmtiEnv *jvmti_env,
JNIEnv* jni_env)
The VM death event notifies the agent of the termination of the VM. No events will occur after the VMDeath event. In the case of VM start-up failure, this event will not be sent. Note that Agent_OnUnload will still be called in these cases.
sent only during the live phase
JVMTI_EVENT_VM_DEATH
51
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread Compiled Method Load
Sent when a method is compiled and loaded into memory by the VM. If it is unloaded, thetypedef struct { const void* start_address; jlocation location; } jvmtiAddrLocationMap;void JNICALL CompiledMethodLoad(jvmtiEnv *jvmti_env, jmethodID method, jint code_size, const void* code_addr, jint map_length, const jvmtiAddrLocationMap* map, const void* compile_info)
CompiledMethodUnload event is sent. If it is moved, the CompiledMethodUnload event is sent, followed by a new CompiledMethodLoad event. Note that a single method may have multiple compiled forms, and that this event will be sent for each form. Note also that several methods may be inlined into a single address range, and that this event will be sent for each method. These events can be sent after their initial occurrence with GenerateEvents.
sent during the start or live phase
JVMTI_EVENT_COMPILED_METHOD_LOAD
68
1.0
jvmtiAddrLocationMap - Native address to location entry Field Type Description start_address const void* Starting native address of code corresponding to a location location jlocation Corresponding location. See GetJLocationFormat for the meaning of location.
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_compiled_method_load_events Can generate events when a method is compiled or unloaded Parameters Name Type Description method jmethodID Method being compiled and loaded code_size jint Size of compiled code code_addr const void* Address where compiled method code is loaded map_length jint Number of jvmtiAddrLocationMap entries in the address map. Zero if mapping information cannot be supplied. map const jvmtiAddrLocationMap* Map from native addresses to location. The native address range of each entry is from start_address to start_address-1 of the next entry. NULL if mapping information cannot be supplied. compile_info const void* VM-specific compilation information. The referenced compile information is managed by the VM and must not depend on the agent for collection. A VM implementation defines the content and lifetime of the information. Compiled Method Unload
void JNICALL
CompiledMethodUnload(jvmtiEnv *jvmti_env,
jmethodID method,
const void* code_addr)
Sent when a compiled method is unloaded from memory. This event might not be sent on the thread which performed the unload. This event may be sent sometime after the unload occurs, but will be sent before the memory is reused by a newly generated compiled method. This event may be sent after the class is unloaded.
sent during the start or live phase
JVMTI_EVENT_COMPILED_METHOD_UNLOAD
69
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_compiled_method_load_events Can generate events when a method is compiled or unloaded Parameters Name Type Description method jmethodID Compiled method being unloaded. For identification of the compiled method only -- the class may be unloaded and therefore the method should not be used as an argument to further JNI or JVM TI functions. code_addr const void* Address where compiled method code was loaded. For identification of the compiled method only -- the space may have been reclaimed. Dynamic Code Generated
void JNICALL
DynamicCodeGenerated(jvmtiEnv *jvmti_env,
const char* name,
const void* address,
jint length)
Sent when a component of the virtual machine is generated dynamically. This does not correspond to Java programming language code that is compiled--see CompiledMethodLoad. This is for native code--for example, an interpreter that is generated differently depending on command-line options. Note that this event has no controlling capability. If a VM cannot generate these events, it simply does not send any. These events can be sent after their initial occurrence with GenerateEvents.
sent during the primordial, start or live phase
JVMTI_EVENT_DYNAMIC_CODE_GENERATED
70
1.0
Capabilities
Required Functionality
Parameters Name Type Descriptionname const char* Name of the code, encoded as a modified UTF-8 string. Intended for display to an end-user. The name might not be unique. address const void* Native address of the code length jint Length in bytes of the code Data Dump Request
Sent by the VM to request the agent to dump its data. This is just a hint and the agent need not react to this event. This is useful for processing command-line signals from users. For example, in the Java 2 SDK a CTRL-Break on Win32 and a CTRL-\ on Linux causes the VM to send this event to the agent.void JNICALL DataDumpRequest(jvmtiEnv *jvmti_env)
sent only during the live phase
JVMTI_EVENT_DATA_DUMP_REQUEST
71
1.0
Capabilities
Required Functionality
Monitor Contended Enter
void JNICALL
MonitorContendedEnter(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object)
Sent when a thread is attempting to enter a Java programming language monitor already acquired by another thread.
sent only during the live phase
JVMTI_EVENT_MONITOR_CONTENDED_ENTER
75
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_monitor_events Can generate events on monitor activity Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread JNI local reference to the thread attempting to enter the monitor object jobject JNI local reference to the monitor Monitor Contended Entered
void JNICALL
MonitorContendedEntered(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object)
Sent when a thread enters a Java programming language monitor after waiting for it to be released by another thread.
sent only during the live phase
JVMTI_EVENT_MONITOR_CONTENDED_ENTERED
76
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_monitor_events Can generate events on monitor activity Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread JNI local reference to the thread entering the monitor object jobject JNI local reference to the monitor Monitor Wait
void JNICALL
MonitorWait(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object,
jlong timeout)
Sent when a thread is about to wait on an object.
sent only during the live phase
JVMTI_EVENT_MONITOR_WAIT
73
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_monitor_events Can generate events on monitor activity Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread JNI local reference to the thread about to wait object jobject JNI local reference to the monitor timeout jlong The number of milliseconds the thread will wait Monitor Waited
void JNICALL
MonitorWaited(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object,
jboolean timed_out)
Sent when a thread finishes waiting on an object.
sent only during the live phase
JVMTI_EVENT_MONITOR_WAITED
74
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_monitor_events Can generate events on monitor activity Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread JNI local reference to the thread that was finished waiting object jobject JNI local reference to the monitor. timed_out jboolean True if the monitor timed out Resource Exhausted
void JNICALL
ResourceExhausted(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jint flags,
const void* reserved,
const char* description)
Sent when a VM resource needed by a running application has been exhausted. Except as required by the optional capabilities, the set of resources which report exhaustion is implementation dependent. The following bit flags define the properties of the resource exhaustion:
Resource Exhaustion Flags Constant Value DescriptionJVMTI_RESOURCE_EXHAUSTED_OOM_ERROR0x0001 After this event returns, the VM will throw ajava.lang.OutOfMemoryError.JVMTI_RESOURCE_EXHAUSTED_JAVA_HEAP0x0002 The VM was unable to allocate memory from the JavaTM platform heap. The heap is the runtime data area from which memory for all class instances and arrays are allocated.JVMTI_RESOURCE_EXHAUSTED_THREADS0x0004 The VM was unable to create a thread.
sent only during the live phase
JVMTI_EVENT_RESOURCE_EXHAUSTED
80
1.1
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread flags jint Flags defining the properties of the of resource exhaustion as specified by the Resource Exhaustion Flags. reserved const void* Reserved. description const char* Description of the resource exhaustion, encoded as a modified UTF-8 string. VM Object Allocation
void JNICALL
VMObjectAlloc(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object,
jclass object_klass,
jlong size)
Sent when a method causes the virtual machine to directly allocate an Object visible to Java programming language code. Generally object allocation should be detected by instrumenting the bytecodes of allocating methods. Object allocation generated in native code by JNI function calls should be detected using JNI function interception. Some methods might not have associated bytecodes and are not native methods, they instead are executed directly by the VM. These methods should send this event. Virtual machines which are incapable of bytecode instrumentation for some or all of their methods can send this event. Note that the SampledObjectAlloc event is triggered on all Java object allocations, including those caused by bytecode method execution, JNI method execution, and directly by VM methods. Typical examples where this event might be sent:
java.lang.Class.newInstance()new and newarray VM instructionsAllocObjectsent only during the live phase
JVMTI_EVENT_VM_OBJECT_ALLOC
84
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_vm_object_alloc_events Can generate events on VM allocation of an object Parameters Name Type Description jni_env JNIEnv * The JNI environment of the event (current) thread thread jthread Thread allocating the object. object jobject JNI local reference to the object that was allocated. object_klass jclass JNI local reference to the class of the object. size jlong Size of the object (in bytes). See GetObjectSize. Sampled Object Allocation
void JNICALL
SampledObjectAlloc(jvmtiEnv *jvmti_env,
JNIEnv* jni_env,
jthread thread,
jobject object,
jclass object_klass,
jlong size)
Sent when an allocated object is sampled. By default, the sampling interval is set to 512KB. The sampling is semi-random to avoid pattern-based bias and provides an approximate overall average interval over long periods of sampling. Each thread tracks how many bytes it has allocated since it sent the last event. When the number of bytes exceeds the sampling interval, it will send another event. This implies that, on average, one object will be sampled every time a thread has allocated 512KB bytes since the last sample. Note that the sampler is pseudo-random: it will not sample every 512KB precisely. The goal of this is to ensure high quality sampling even if allocation is happening in a fixed pattern (i.e., the same set of objects are being allocated every 512KB). If another sampling interval is required, the user can call SetHeapSamplingInterval with a strictly positive integer value, representing the new sampling interval. This event is sent once the sampled allocation has been performed. It provides the object, stack trace of the allocation, the thread allocating, the size of allocation, and the object's class. A typical use case of this system is to determine where heap allocations originate. In conjunction with weak references and the function GetStackTrace, a user can track which objects were allocated from which stack trace, and which are still live during the execution of the program.
sent only during the live phase
JVMTI_EVENT_SAMPLED_OBJECT_ALLOC
86
11
Parameters Name Type Descriptionjni_env JNIEnv * The JNI environment of the event (current) thread. thread jthread Thread allocating the object. object jobject JNI local reference to the object that was allocated. object_klass jclass JNI local reference to the class of the object size jlong Size of the object (in bytes). See GetObjectSize. Object Free
void JNICALL
ObjectFree(jvmtiEnv *jvmti_env,
jlong tag)
An Object Free event is sent when the garbage collector frees an object. Events are only sent for tagged objects--see heap functions. The event handler must not use JNI functions and must not use JVM TI functions except those which specifically allow such use (see the raw monitor, memory management, and environment local storage functions).
sent only during the live phase
JVMTI_EVENT_OBJECT_FREE
83
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_object_free_events Can generate events when the garbage collector frees an object Parameters Name Type Description tag jlong The freed object's tag Garbage Collection Start
A Garbage Collection Start event is sent when a garbage collection pause begins. Only stop-the-world collections are reported--that is, collections during which all threads cease to modify the state of the Java virtual machine. This means that some collectors will never generate these events. This event is sent while the VM is still stopped, thus the event handler must not use JNI functions and must not use JVM TI functions except those which specifically allow such use (see the raw monitor, memory management, and environment local storage functions). This event is always sent as a matched pair withvoid JNICALL GarbageCollectionStart(jvmtiEnv *jvmti_env)
GarbageCollectionFinish (assuming both events are enabled) and no garbage collection events will occur between them.
sent only during the live phase
JVMTI_EVENT_GARBAGE_COLLECTION_START
81
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_garbage_collection_events Can generate events when garbage collection begins or ends Garbage Collection Finish
A Garbage Collection Finish event is sent when a garbage collection pause ends. This event is sent while the VM is still stopped, thus the event handler must not use JNI functions and must not use JVM TI functions except those which specifically allow such use (see the raw monitor, memory management, and environment local storage functions). Some agents may need to do post garbage collection operations that require the use of the disallowed JVM TI or JNI functions. For these cases an agent thread can be created which waits on a raw monitor, and the handler for the Garbage Collection Finish event simply notifies the raw monitor This event is always sent as a matched pair withvoid JNICALL GarbageCollectionFinish(jvmtiEnv *jvmti_env)
GarbageCollectionStart (assuming both events are enabled).
sent only during the live phase
JVMTI_EVENT_GARBAGE_COLLECTION_FINISH
82
1.0
Capabilities
Optional Functionality:might not be implemented for all virtual machines. The following capability (as returned by
GetCapabilities
) must be true to use this event.
Capability Effectcan_generate_garbage_collection_events Can generate events when garbage collection begins or ends Constant Index
Change History Last update: 09/05/07JVMTI_CLASS_STATUS_ARRAYJVMTI_CLASS_STATUS_ERRORJVMTI_CLASS_STATUS_INITIALIZEDJVMTI_CLASS_STATUS_PREPAREDJVMTI_CLASS_STATUS_PRIMITIVEJVMTI_CLASS_STATUS_VERIFIEDJVMTI_DISABLEJVMTI_ENABLEJVMTI_HEAP_FILTER_CLASS_TAGGEDJVMTI_HEAP_FILTER_CLASS_UNTAGGEDJVMTI_HEAP_FILTER_TAGGEDJVMTI_HEAP_FILTER_UNTAGGEDJVMTI_HEAP_OBJECT_EITHERJVMTI_HEAP_OBJECT_TAGGEDJVMTI_HEAP_OBJECT_UNTAGGEDJVMTI_HEAP_REFERENCE_ARRAY_ELEMENTJVMTI_HEAP_REFERENCE_CLASSJVMTI_HEAP_REFERENCE_CLASS_LOADERJVMTI_HEAP_REFERENCE_CONSTANT_POOLJVMTI_HEAP_REFERENCE_FIELDJVMTI_HEAP_REFERENCE_INTERFACEJVMTI_HEAP_REFERENCE_JNI_GLOBALJVMTI_HEAP_REFERENCE_JNI_LOCALJVMTI_HEAP_REFERENCE_MONITORJVMTI_HEAP_REFERENCE_OTHERJVMTI_HEAP_REFERENCE_PROTECTION_DOMAINJVMTI_HEAP_REFERENCE_SIGNERSJVMTI_HEAP_REFERENCE_STACK_LOCALJVMTI_HEAP_REFERENCE_STATIC_FIELDJVMTI_HEAP_REFERENCE_SUPERCLASSJVMTI_HEAP_REFERENCE_SYSTEM_CLASSJVMTI_HEAP_REFERENCE_THREADJVMTI_HEAP_ROOT_JNI_GLOBALJVMTI_HEAP_ROOT_JNI_LOCALJVMTI_HEAP_ROOT_MONITORJVMTI_HEAP_ROOT_OTHERJVMTI_HEAP_ROOT_STACK_LOCALJVMTI_HEAP_ROOT_SYSTEM_CLASSJVMTI_HEAP_ROOT_THREADJVMTI_ITERATION_ABORTJVMTI_ITERATION_CONTINUEJVMTI_ITERATION_IGNOREJVMTI_JAVA_LANG_THREAD_STATE_BLOCKEDJVMTI_JAVA_LANG_THREAD_STATE_MASKJVMTI_JAVA_LANG_THREAD_STATE_NEWJVMTI_JAVA_LANG_THREAD_STATE_RUNNABLEJVMTI_JAVA_LANG_THREAD_STATE_TERMINATEDJVMTI_JAVA_LANG_THREAD_STATE_TIMED_WAITINGJVMTI_JAVA_LANG_THREAD_STATE_WAITINGJVMTI_JLOCATION_JVMBCIJVMTI_JLOCATION_MACHINEPCJVMTI_JLOCATION_OTHERJVMTI_KIND_ALLOC_ALLOC_BUFJVMTI_KIND_ALLOC_BUFJVMTI_KIND_INJVMTI_KIND_IN_BUFJVMTI_KIND_IN_PTRJVMTI_KIND_OUTJVMTI_KIND_OUT_BUFJVMTI_PHASE_DEADJVMTI_PHASE_LIVEJVMTI_PHASE_ONLOADJVMTI_PHASE_PRIMORDIALJVMTI_PHASE_STARTJVMTI_PRIMITIVE_TYPE_BOOLEANJVMTI_PRIMITIVE_TYPE_BYTEJVMTI_PRIMITIVE_TYPE_CHARJVMTI_PRIMITIVE_TYPE_DOUBLEJVMTI_PRIMITIVE_TYPE_FLOATJVMTI_PRIMITIVE_TYPE_INTJVMTI_PRIMITIVE_TYPE_LONGJVMTI_PRIMITIVE_TYPE_SHORTJVMTI_REFERENCE_ARRAY_ELEMENTJVMTI_REFERENCE_CLASSJVMTI_REFERENCE_CLASS_LOADERJVMTI_REFERENCE_CONSTANT_POOLJVMTI_REFERENCE_FIELDJVMTI_REFERENCE_INTERFACEJVMTI_REFERENCE_PROTECTION_DOMAINJVMTI_REFERENCE_SIGNERSJVMTI_REFERENCE_STATIC_FIELDJVMTI_RESOURCE_EXHAUSTED_JAVA_HEAPJVMTI_RESOURCE_EXHAUSTED_OOM_ERRORJVMTI_RESOURCE_EXHAUSTED_THREADSJVMTI_THREAD_MAX_PRIORITYJVMTI_THREAD_MIN_PRIORITYJVMTI_THREAD_NORM_PRIORITYJVMTI_THREAD_STATE_ALIVEJVMTI_THREAD_STATE_BLOCKED_ON_MONITOR_ENTERJVMTI_THREAD_STATE_IN_NATIVEJVMTI_THREAD_STATE_IN_OBJECT_WAITJVMTI_THREAD_STATE_INTERRUPTEDJVMTI_THREAD_STATE_PARKEDJVMTI_THREAD_STATE_RUNNABLEJVMTI_THREAD_STATE_SLEEPINGJVMTI_THREAD_STATE_SUSPENDEDJVMTI_THREAD_STATE_TERMINATEDJVMTI_THREAD_STATE_VENDOR_1JVMTI_THREAD_STATE_VENDOR_2JVMTI_THREAD_STATE_VENDOR_3JVMTI_THREAD_STATE_WAITINGJVMTI_THREAD_STATE_WAITING_INDEFINITELYJVMTI_THREAD_STATE_WAITING_WITH_TIMEOUTJVMTI_TIMER_ELAPSEDJVMTI_TIMER_TOTAL_CPUJVMTI_TIMER_USER_CPUJVMTI_TYPE_CCHARJVMTI_TYPE_CVOIDJVMTI_TYPE_JBOOLEANJVMTI_TYPE_JBYTEJVMTI_TYPE_JCHARJVMTI_TYPE_JCLASSJVMTI_TYPE_JDOUBLEJVMTI_TYPE_JFIELDIDJVMTI_TYPE_JFLOATJVMTI_TYPE_JINTJVMTI_TYPE_JLONGJVMTI_TYPE_JMETHODIDJVMTI_TYPE_JNIENVJVMTI_TYPE_JOBJECTJVMTI_TYPE_JSHORTJVMTI_TYPE_JTHREADJVMTI_TYPE_JVALUEJVMTI_VERBOSE_CLASSJVMTI_VERBOSE_GCJVMTI_VERBOSE_JNIJVMTI_VERBOSE_OTHERJVMTI_VERSION_INTERFACE_JNIJVMTI_VERSION_INTERFACE_JVMTIJVMTI_VERSION_MASK_INTERFACE_TYPEJVMTI_VERSION_MASK_MAJORJVMTI_VERSION_MASK_MICROJVMTI_VERSION_MASK_MINORJVMTI_VERSION_SHIFT_MAJORJVMTI_VERSION_SHIFT_MICROJVMTI_VERSION_SHIFT_MINORJVMTI_VISIT_ABORTJVMTI_VISIT_OBJECTS
GetVersionNumber function. Version
VMObjectAlloc event. 30 Nov 2002 Add DynamicCodeGenerated event. 30 Nov 2002 Add const to declarations. 30 Nov 2002 Change method exit and frame pop to send on exception. 1 Dec 2002 Add ForceGarbageCollection. 2 Dec 2002 Redo Xrun section; clarify GetStackTrace and add example; Fix width problems; use "agent" consistently. 8 Dec 2002 Remove previous start-up intro. Add JVM TI Environments section. 8 Dec 2002 Add DisposeEnvironment. 9 Dec 2002 Numerous minor updates. 15 Dec 2002 Add heap profiling functions added: get/set annotation, iterate live objects/heap. Add heap profiling functions place holder added: heap roots. Heap profiling event added: object free. Heap profiling event redesigned: vm object allocation. Heap profiling event placeholders added: garbage collection start/finish. Native method bind event added. 19 Dec 2002 Revamp suspend/resume functions. Add origin information with jvmdi tag. Misc fixes. 24 Dec 2002 Add semantics to types. 27 Dec 2002 Add local reference section. Autogenerate parameter descriptions from types. 28 Dec 2002 Document that RunAgentThread sends threadStart. 29 Dec 2002 Remove redundant local ref and dealloc warning. Convert GetRawMonitorName to allocated buffer. Add GenerateEvents. 30 Dec 2002 Make raw monitors a type and rename to "jrawMonitorID". 1 Jan 2003 Include origin information. Clean-up JVMDI issue references. Remove Deallocate warnings which are now automatically generated. 2 Jan 2003 Fix representation issues for jthread. 3 Jan 2003 Make capabilities buffered out to 64 bits - and do it automatically. 4 Jan 2003 Make constants which are enumeration into enum types. Parameters now of enum type. Clean-up and index type section. Replace remaining datadef entities with callback. 7 Jan 2003 Correct GenerateEvents description. More internal semantics work. 9 Jan 2003 Replace previous GetSystemProperties with two functions which use allocated information instead fixed. Add SetSystemProperty. More internal semantics work. 12 Jan 2003 Add varargs to end of SetEventNotificationMode. 20 Jan 2003 Finish fixing spec to reflect that alloc sizes are jlong. 22 Jan 2003 Allow NULL as RunAgentThread arg. 22 Jan 2003 Fixed names to standardized naming convention Removed AsyncGetStackTrace. 29 Jan 2003 Since we are using jthread, removed GetThread. 31 Jan 2003 Change GetFieldName to allow NULLs like GetMethodName. v40
GetThreadStatus. GetClassLoader return NULL for the bootstrap class loader. Add GetClassName issue. Define local variable signature. Disallow zero in annotations array of GetObjectsWithAnnotations. Remove over specification in GetObjectsWithAnnotations. Elide SetAllocationHooks. Elide SuspendAllThreads. v63
jvmtiEventCallbacks. Zero length allocations return NULL. Keep SetAllocationHooks in JVMDI, but remove from JVM TI. Add JVMTI_THREAD_STATUS_FLAG_INTERRUPTED. v64
can_redefine_any_class and can_generate_all_class_hook_events) and an error (JVMTI_ERROR_UNMODIFIABLE_CLASS) which allow some classes to be unmodifiable. 0.3.11
RetransformClasses. Revamp the bytecode instrumentation documentation. Change IsMethodObsolete to no longer require the can_redefine_classes capability. 1.1.63
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