If you find that Sentry's tracing functionality is generating too much data, for example, if you notice your spans quota is quickly being exhausted, you can choose to sample your traces.
Effective sampling is key to getting the most value from Sentry's performance monitoring while minimizing overhead. The Python SDK provides two ways to control the sampling rate. You can review the options and examples below.
Sampling Configuration Options 1. Uniform Sample Rate (traces_sample_rate
)
traces_sample_rate
is a floating-point value between 0.0
and 1.0
, inclusive, which controls the probability with which each transaction will be sampled:
Copied
sentry_sdk.init(
traces_sample_rate=1.0,
)
With traces_sample_rate
set to 0.25
, each transaction in your application is randomly sampled with a probability of 0.25
, so you can expect that one in every four transactions will be sent to Sentry.
traces_sampler
)
For more granular control, you can provide a traces_sampler
function. This approach allows you to:
It is strongly recommended when using a custom traces_sampler
that you respect the parent sampling decision. This ensures your traces will be complete.
In distributed systems, implementing inheritance logic when trace information is propagated between services will ensure consistent sampling decisions across your entire distributed trace.
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
if "...":
return 0.5
elif "...":
return 0.01
elif "...":
return 0
return 0.1
sentry_sdk.init(
traces_sampler=traces_sampler,
)
Traces Sampler Examples Traces Sampler Examples
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
transaction_ctx = sampling_context["transaction_context"]
name = transaction_ctx["name"]
op = transaction_ctx["op"]
if name and ('/checkout' in name or op == 'checkout'):
return 1.0
if name and ('/login' in name or op == 'login'):
return 0.5
return 0.1
sentry_sdk.init(
dsn="your-dsn",
traces_sampler=traces_sampler,
)
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
custom_sampling_ctx = sampling_context["custom_sampling_context"]
environment = os.environ.get("ENVIRONMENT", "development")
if environment == "development":
return 1.0
if custom_sampling_ctx.get("hasRecentErrors") is True:
return 0.8
if environment == "production":
return 0.05
elif environment == "staging":
return 0.2
return 0.1
sentry_sdk.init(
dsn="your-dsn",
traces_sampler=traces_sampler,
)
with sentry_sdk.start_transaction(
name="GET /api/users",
op="http.request",
custom_sampling_context={"hasRecentErrors": True},
) as transaction:
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
custom_sampling_ctx = sampling_context["custom_sampling_context"]
if custom_sampling_ctx.get("user", {}).get("tier") == "premium":
return 1.0
if custom_sampling_ctx.get("hasRecentErrors") is True:
return 0.8
name = sampling_context["transaction_context"]["name"]
if name and name.startswith("/api/metrics"):
return 0.01
return 0.2
sentry_sdk.init(
dsn="your-dsn",
traces_sampler=traces_sampler,
)
with sentry_sdk.start_transaction(
name="GET /api/users",
op="http.request",
custom_sampling_context={"user": {"tier": "premium"}, "hasRecentErrors": True},
) as transaction:
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
transaction_ctx = sampling_context["transaction_context"]
if transaction_ctx["op"] in ["payment.process", "order.create", "user.verify"]:
return 1.0
custom_sampling_context = sampling_context["custom_sampling_context"]
user_segment = custom_sampling_context.get("user", {}).get("segment")
if user_segment == "enterprise":
return 0.8
elif user_segment == "premium":
return 0.5
transaction_value = custom_sampling_context.get("transaction", {}).get("value")
if transaction_value is not None and transaction_value > 1000:
return 0.7
error_rate = custom_sampling_context.get("service", {}).get("error_rate")
if error_rate is not None and error_rate > 0.05:
return 0.9
return 0.1
sentry_sdk.init(
dsn="your-dsn",
traces_sampler=traces_sampler,
)
with sentry_sdk.start_transaction(
name="Process Payment",
op="payment.process",
custom_sampling_context={"user": {"segment": "enterprise"}, "transaction": {"value": 1500}, "service": {"error_rate": 0.03}},
) as transaction:
Copied
import sentry_sdk
from sentry_sdk.types import SamplingContext
def traces_sampler(sampling_context: SamplingContext) -> float:
parent_sampling_decision = sampling_context["parent_sampled"]
if parent_sampling_decision is not None:
return float(parent_sampling_decision)
custom_sampling_ctx = sampling_context["custom_sampling_context"]
memory_usage = custom_sampling_ctx.get("memory_usage_mb")
if memory_usage is not None and memory_usage > 500:
return 0.8
cpu_percent = custom_sampling_ctx.get("cpu_percent")
if cpu_percent is not None and cpu_percent > 80:
return 0.8
db_connections = custom_sampling_ctx.get("db_connections")
if db_connections is not None and db_connections > 100:
return 0.7
return 0.1
sentry_sdk.init(
dsn="your-dsn",
traces_sampler=traces_sampler,
)
with sentry_sdk.start_transaction(
name="Process Data",
op="data.process",
custom_sampling_context={"memory_usage_mb": 600, "cpu_percent": 85, "db_connections": 120},
) as transaction:
The Sampling Context Object
When the traces_sampler
function is called, the Sentry SDK passes a sampling_context
object with information from the relevant span to help make sampling decisions:
Copied
{
"transaction_context": {
"name": str,
"op": str,
"data": Optional[dict[str, Any]]
},
"parent_sampled": Optional[bool],
"parent_sample_rate": Optional[float],
"custom_sampling_context": Optional[dict[str, Any]]
}
SDK-Provided vs. Custom Attributes
The sampling context contains both SDK-provided attributes and custom attributes:
SDK-Provided Attributes:
transaction_context.name
: The name of the transactiontransaction_context.op
: The operation typeparent_sampled
: Whether the parent transaction was sampledparent_sample_rate
: The sample rate used by the parentCustom Attributes:
custom_sampling_context
parameter in start_transaction
. Use this for data that you want to use for sampling decisions but don't want to include in the transaction data that gets sent to Sentry. Read more about sampling context here.When multiple sampling mechanisms could apply, Sentry follows this order of precedence:
start_transaction
, that decision is usedtraces_sampler
is defined, its decision is used. Although the traces_sampler
can override the parent sampling decision, most users will want to ensure their traces_sampler
respects the parent sampling decisiontraces_sampler
is defined, but there is a parent sampling decision from an incoming distributed trace, we use the parent sampling decisiontraces_sample_rate
is usedtraces_sample_rate=0.0
Sentry uses a "head-based" sampling approach:
The two key headers are:
sentry-trace
: Contains trace ID, span ID, and sampling decisionbaggage
: Contains additional trace metadata including sample rateThe Sentry Python SDK automatically attaches these headers to outgoing HTTP requests when using auto-instrumentation with libraries like requests
, urllib3
, or httpx
. For other communication channels, you can manually propagate trace information. Learn more about customizing tracing in custom trace propagation
RetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.4