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GeezerVison is showing github.com — gh-108724: Fix _PySemaphore_Wait call during thread deletion by colesbury · Pull Request #116483 · python/cpython

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@colesbury

@colesbury colesbury commented Mar 7, 2024 •
edited by bedevere-app Bot
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In general, when _PyThreadState_GET() is non-NULL then the current thread is "attached", but there is a small window during PyThreadState_DeleteCurrent() where that's not true: tstate_delete_common() is called when the thread is detached, but before current_fast_clear().

This updates _PySemaphore_Wait() to handle that case.

  • Issue: Add lightweight locking C API #108724

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@colesbury colesbury added skip news topic-free-threading labels Mar 7, 2024
@colesbury
colesbury requested review from DinoV and ericsnowcurrently March 7, 2024 23:28
@bedevere-app bedevere-app Bot added the awaiting core review label Mar 7, 2024
@colesbury
pythongh-108724: Fix _PySemaphore_Wait call during thread deletion
6a6ca9e 
In general, when `_PyThreadState_GET()` is non-NULL then the current
thread is "attached", but there is a small window during
`PyThreadState_DeleteCurrent()` where that's not true:
tstate_delete_common is called when the thread is detached, but before
current_fast_clear().

This updates _PySemaphore_Wait() to handle that case.
@colesbury
colesbury force-pushed the gh-108724-sema-wait branch from e4aa866 to 6a6ca9e Compare March 7, 2024 23:29
@colesbury colesbury changed the title gh-116480: Fix _PySemaphore_Wait call during thread deletion gh-108724: Fix _PySemaphore_Wait call during thread deletion Mar 7, 2024
@bedevere-app bedevere-app Bot mentioned this pull request Mar 7, 2024
Add lightweight locking C API #108724
Closed
ericsnowcurrently
ericsnowcurrently approved these changes Mar 8, 2024
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LGTM

I have one very minor comment about the applicability of the PyEval_ReleaseThread() call. Feel free to address it (or not) how you think makes sense.

As to the motivation for this PR, should we aim for eliminating the small window you described in PR description? It vaguely feels like something is our of whack with that.

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Comment thread Python/parking_lot.c Resolved

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@bedevere-app bedevere-app Bot added awaiting merge and removed awaiting core review labels Mar 8, 2024
colesbury and others added 2 commits March 8, 2024 14:52
@colesbury @ericsnowcurrently
Update Python/parking_lot.c
341650b 
Co-authored-by: Eric Snow <[email protected]>
@colesbury
Use variant of Eric's second suggestion
69dc393
@colesbury

colesbury commented Mar 8, 2024

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As to the motivation for this PR, should we aim for eliminating the small window you described in PR description? It vaguely feels like something is our of whack with that.

Yeah, I'll put up another PR that does that as well.
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@colesbury colesbury mentioned this pull request Mar 8, 2024
Ensure current thread state is cleared before deleting it in _PyThreadState_DeleteCurrent #116515
Closed
@colesbury
colesbury merged commit 3cdfdc0 into python:main Mar 8, 2024
@bedevere-app bedevere-app Bot removed the awaiting merge label Mar 8, 2024
@colesbury
colesbury deleted the gh-108724-sema-wait branch March 8, 2024 20:26
adorilson pushed a commit to adorilson/cpython that referenced this pull request Mar 25, 2024
@colesbury @ericsnowcurrently @adorilson
pythongh-108724: Fix _PySemaphore_Wait call during thread deletion (p…
69af643 
…ython#116483)

In general, when `_PyThreadState_GET()` is non-NULL then the current
thread is "attached", but there is a small window during
`PyThreadState_DeleteCurrent()` where that's not true:
tstate_delete_common() is called when the thread is detached, but before
current_fast_clear().

Co-authored-by: Eric Snow <[email protected]>
diegorusso pushed a commit to diegorusso/cpython that referenced this pull request Apr 17, 2024
@colesbury @ericsnowcurrently @diegorusso
pythongh-108724: Fix _PySemaphore_Wait call during thread deletion (p…
9fe596e 
…ython#116483)

In general, when `_PyThreadState_GET()` is non-NULL then the current
thread is "attached", but there is a small window during
`PyThreadState_DeleteCurrent()` where that's not true:
tstate_delete_common() is called when the thread is detached, but before
current_fast_clear().

Co-authored-by: Eric Snow <[email protected]>
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@ericsnowcurrently ericsnowcurrently ericsnowcurrently approved these changes
@DinoV DinoV Awaiting requested review from DinoV

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@colesbury @ericsnowcurrently
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