[Python-Dev] GC pauses in CPython

[Maciej Fijalkowski]

On Mon, Oct 14, 2013 at 2:34 PM, Antoine Pitrou <solipsis at pitrou.net> wrote:
> Le Mon, 14 Oct 2013 14:25:18 +0200,
> Maciej Fijalkowski <fijall at gmail.com> a écrit :
>> On Mon, Oct 14, 2013 at 2:11 PM, "Martin v. Löwis"
>> <martin at v.loewis.de> wrote:
>> > Am 14.10.13 13:49, schrieb Maciej Fijalkowski:
>> >> I'm working on an incremental GC for PyPy. How do I measure GC
>> >> pauses in CPython? (that is, the circular reference searching
>> >> stuff)
>> >
>> > I would instrument the interpreter. The tricky part may be to
>> > subtract the time for any resulting finalization (and whether or
>> > not to subtract that at all).
>> >
>> > Regards,
>> > Martin
>> >
>>
>> seems that:
>>
>> gc.set_debug(gc.DEBUG_STATS) does the job
>>
>> obviously timing gc.collect is quite the opposite of what I'm trying
>> to achieve (see how cpython deals with when to collect)
>
> Why "the opposite"? The time of a GC pause in CPython is the time
> executing gc.collect(). And most of the time gc.collect() will spend
> its time walking live objects, not dead ones, so executing it multiple
> times should only introduce a minor bias.

well, I'm not trying to measure it at *one point in time* but to
provide some statistics. invoking it kills the point quite a bit.