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GeezerVison is showing github.com — gh-129185: Use PyMutex in tracemalloc by vstinner · Pull Request #129246 · python/cpython

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@vstinner

@vstinner vstinner commented Jan 23, 2025 •
edited by bedevere-app Bot
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  • Issue: Segmentation fault during interpreter finalization in PyTraceMalloc_Untrack #129185

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@vstinner
pythongh-129185: Use PyMutex in tracemalloc
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@bedevere-app bedevere-app Bot added the awaiting core review label Jan 23, 2025
@bedevere-app bedevere-app Bot mentioned this pull request Jan 23, 2025
Segmentation fault during interpreter finalization in PyTraceMalloc_Untrack #129185
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@vstinner vstinner added the skip news label Jan 23, 2025
@vstinner

vstinner commented Jan 23, 2025

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cc @ZeroIntensity
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vstinner
vstinner commented Jan 23, 2025
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Comment thread Python/tracemalloc.c
#define tables_lock _PyRuntime.tracemalloc.tables_lock
#define TABLES_LOCK() PyThread_acquire_lock(tables_lock, 1)
#define TABLES_UNLOCK() PyThread_release_lock(tables_lock)
#define TABLES_LOCK() PyMutex_LockFlags(&tables_lock, _Py_LOCK_DONT_DETACH)

@vstinner vstinner Jan 23, 2025 •
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PyMutex_Lock(&tables_lock) cannot be used "free" allocator hooks which don't acquire the GIL.

Maybe PyMutex_Lock(&tables_lock) should be preferred in functions which hold the GIL?

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@ZeroIntensity ZeroIntensity Jan 23, 2025 •
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I don't think it matters. TABLES_LOCK() didn't detach the thread state before, no need to now. (In fact, some unpredictable things might happen if another thread takes the GIL and then uses tracemalloc.)

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ZeroIntensity
ZeroIntensity approved these changes Jan 24, 2025
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LGTM. We should also consider using _Py_atomic for some fields (especially tracing).

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@vstinner
vstinner merged commit c005ea4 into python:main Jan 24, 2025
@vstinner
vstinner deleted the tracemalloc_pymutex branch January 24, 2025 10:25
@bedevere-app bedevere-app Bot removed the awaiting core review label Jan 24, 2025
@encukou encukou mentioned this pull request Sep 30, 2025
Potential deadlock in test_tracemalloc with the FT build and tail-call dispatch. #139116
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@ZeroIntensity ZeroIntensity ZeroIntensity approved these changes

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@vstinner @ZeroIntensity
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