Bruno Desthuilliers wrote:
> mk a écrit :
>> Obviously, don't try this on low-memory machine:
>>
>>>>> a={}
>>>>> for i in range(10000000):
> Note that in Python 2, this will build a list of 10000000 int objects.
> You may want to use xrange instead...
Huh? I was under impression that some time after 2.0 range was made to
work "under the covers" like xrange when used in a loop? Or is it 3.0
that does that?
> And this build yet another list of 10000000 int objects.
Well this explains much of the overhead.
> (overly simplified)
>
> When an object is garbage-collected, the memory is not necessarily
> "returned" to the system - and the system doesn't necessarily claim it
> back neither until it _really_ needs it.
>
> This avoid a _lot_ of possibly useless work for both the python
> interpreter (keeping already allocated memory costs less than immediatly
> returning it, just to try and allocate some more memory a couple
> instructions later) and the system (ditto - FWIW, how linux handles
> memory allocations is somewhat funny, if you ever programmed in C).
Ah! That explains a lot. Thanks to you, I have again expanded my
knowledge of Python!
Hmm I would definitely like to read smth on how CPython handles memory
on Python wiki. Thanks for that doc on wiki on "functions & methods" to
you and John Posner, I'm reading it every day like a bible. ;-)
Regards,
mk
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