[Python-Dev] Does anyone use threading debug PYTHONTHREADDEBUG=1 env var? Can I remove it?

[Victor Stinner]

Hi,

Does anyone use threading debug PYTHONTHREADDEBUG=1 env var on a
Python debug build? If not, can I just remove it?

--

To fix a race condition at thread exit on Linux using the glibc, I
removed calls to pthread_exit() (PyThread_exit_thread()) in the
_thread module:

   https://bugs.python.org/issue44434

A side effect of this change is the removal of the
"PyThread_exit_thread called" threading debug log when using
PYTHONTHREADDEBUG=1 environment variable.

I never used PYTHONTHREADDEBUG. I just tried it and it produces tons
of output in stdout about locks. It looks basically useless because it
produces way too many logs, and it pollutes stdout (ex: most Python
tests fail when it's enabled).

This debug mode requires to build Python in debug mode (./configure
--with-pydebug):

   https://docs.python.org/dev/using/configure.html#python-debug-build

IMO there are enough external debugging tools to debug threading
issues. Python no longer has to come with its built-in logs.

I propose to deprecate the feature in Python 3.11 and remove it in 2
releases (Python 3.13).

Victor
-- 
Night gathers, and now my watch begins. It shall not end until my death.
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[Python-Dev] Re: Does anyone use threading debug PYTHONTHREADDEBUG=1 env var? Can I remove it?

[Gregory P. Smith]

On Wed, Jul 7, 2021 at 2:28 AM Victor Stinner  wrote:

> Hi,
>
> Does anyone use threading debug PYTHONTHREADDEBUG=1 env var on a
> Python debug build? If not, can I just remove it?
>
> --
>
> To fix a race condition at thread exit on Linux using the glibc, I
> removed calls to pthread_exit() (PyThread_exit_thread()) in the
> _thread module:
>
>https://bugs.python.org/issue44434
>
> A side effect of this change is the removal of the
> "PyThread_exit_thread called" threading debug log when using
> PYTHONTHREADDEBUG=1 environment variable.
>
> I never used PYTHONTHREADDEBUG. I just tried it and it produces tons
> of output in stdout about locks. It looks basically useless because it
> produces way too many logs, and it pollutes stdout (ex: most Python
> tests fail when it's enabled).
>
> This debug mode requires to build Python in debug mode (./configure
> --with-pydebug):
>
>https://docs.python.org/dev/using/configure.html#python-debug-build
>
> IMO there are enough external debugging tools to debug threading
> issues. Python no longer has to come with its built-in logs.
>
> I propose to deprecate the feature in Python 3.11 and remove it in 2
> releases (Python 3.13).
>

I agree with its removal.


> Victor
> --
> Night gathers, and now my watch begins. It shall not end until my death.
> ___
> Python-Dev mailing list -- python-dev@python.org
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> Code of Conduct: http://python.org/psf/codeofconduct/
>
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[Python-Dev] Re: Does anyone use threading debug PYTHONTHREADDEBUG=1 env var? Can I remove it?

[Guido van Rossum]

I agree, that flag was probably last useful when we were debugging the
threading machinery itself. (Evidenced by it only working on
--with-pydebug, which is for when you're debugging CPython itself, not any
user apps.)

On Wed, Jul 7, 2021 at 9:33 AM Gregory P. Smith  wrote:

>
>
> On Wed, Jul 7, 2021 at 2:28 AM Victor Stinner  wrote:
>
>> Hi,
>>
>> Does anyone use threading debug PYTHONTHREADDEBUG=1 env var on a
>> Python debug build? If not, can I just remove it?
>>
>> --
>>
>> To fix a race condition at thread exit on Linux using the glibc, I
>> removed calls to pthread_exit() (PyThread_exit_thread()) in the
>> _thread module:
>>
>>https://bugs.python.org/issue44434
>>
>> A side effect of this change is the removal of the
>> "PyThread_exit_thread called" threading debug log when using
>> PYTHONTHREADDEBUG=1 environment variable.
>>
>> I never used PYTHONTHREADDEBUG. I just tried it and it produces tons
>> of output in stdout about locks. It looks basically useless because it
>> produces way too many logs, and it pollutes stdout (ex: most Python
>> tests fail when it's enabled).
>>
>> This debug mode requires to build Python in debug mode (./configure
>> --with-pydebug):
>>
>>https://docs.python.org/dev/using/configure.html#python-debug-build
>>
>> IMO there are enough external debugging tools to debug threading
>> issues. Python no longer has to come with its built-in logs.
>>
>> I propose to deprecate the feature in Python 3.11 and remove it in 2
>> releases (Python 3.13).
>>
>
> I agree with its removal.
>
>
>> Victor
>> --
>> Night gathers, and now my watch begins. It shall not end until my death.
>> ___
>> Python-Dev mailing list -- python-dev@python.org
>> To unsubscribe send an email to python-dev-le...@python.org
>> https://mail.python.org/mailman3/lists/python-dev.python.org/
>> Message archived at
>> https://mail.python.org/archives/list/python-dev@python.org/message/NMLGCDRUKLZSTK4UICJTKR54WRXU2ZGJ/
>> Code of Conduct: http://python.org/psf/codeofconduct/
>>
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>


-- 
--Guido van Rossum (python.org/~guido)
*Pronouns: he/him **(why is my pronoun here?)*

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