----- Original Message -----
> From: "Victor Stinner" <vstin...@python.org>
> To: "Python Dev" <Python-Dev@python.org>
> Sent: Wednesday, January 29, 2020 10:57:02 PM
> Subject: [Python-Dev] Remove COUNT_ALLOCS special build
>
> Hi,
>
> I would like to confirm that there is no user of the Python
> "COUNT_ALLOCS" special build, because I plan to remove it from Python
> 3.9. If you use it, please raise your hand and explain why other debug
> tools don't fit your specific use case.
>
> --
>
> I'm always annoyed by "#ifdef COUNT_ALLOCS" code which is common in
> code related to reference counting (object.h, object.c, typeobject.c).
> It makes the code harder to read and harder to maintain. It's a 27
> years old feature which always required to rebuild Python with
> COUNT_ALLOCS macro defined. In clear, you have to know about the
> feature and build your own Python binary to use it.
>
> COUNT_ALLOCS was used for 6 years (2010-2015) in the debug build of
> Python of the Fedora package. Sadly, C extensions provided by Fedora
> are only built in release mode, and so cannot be used by the debug
> build. python2.7-debug requires to rebuild all C extensions in debug
> mode. IMHO nobody ever used python2.7-debug to debug real
> applications.
>
> The feature was added to Fedora debug build by Dave Malcolm in 2010 to
> help him to debug memory leaks. Later, he wrote: "I don't think this
> patch ever really bought us much, and it sounds like there are better
> tools for this now, so feel free to drop the COUNT_ALLOC patches." So
> the feature was dropped from Python 3 package in 2015.
>
> I never ever used this feature. I consider that there are now way
> better tools to debug memory leaks in Python 3, like tracemalloc and
> multiple tools based on gc.get_objects().
>
> I failed to find any user of COUNT_ALLOCS on the Internet. I'm quite
> sure that many core developers never heard about this special build.
>
> I proposed https://bugs.python.org/issue39489 and
> https://github.com/python/cpython/pull/18259 to remove the feature. My
> PR basically only removes code:
>
> 34 files changed, 24 insertions(+), 470 deletions(-)
>
> Do you see any reason to keep COUNT_ALLOCS in Python 3.9? If yes,
> please elaborate :-)
>
> Victor
> --
> Night gathers, and now my watch begins. It shall not end until my death.
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>
>
I've never used this feature and it was quite the hassle to maintain those
patches downstream, so in my biased opinion, I would welcome the removal.
--
Regards,
Charalampos Stratakis
Software Engineer
Python Maintenance Team, Red Hat
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