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Add fallback implementation of PyCriticalSection_BeginMutex for Python 3.13t #5981

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Merged
rwgk merged 20 commits into from
Feb 10, 2026
Merged

Add fallback implementation of PyCriticalSection_BeginMutex for Python 3.13t #5981

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d569c4c
Add failback implementation of `PyCriticalSection_BeginMutex` for Pyt…
XuehaiPan Feb 2, 2026
5e7d423
Add comment for Python version
XuehaiPan Feb 2, 2026
9de6d1a
Use `_PyCriticalSection_BeginSlow`
XuehaiPan Feb 2, 2026
00bcf66
Add forward declaration
XuehaiPan Feb 2, 2026
225cb46
Fix forward declaration
XuehaiPan Feb 2, 2026
0e6ffd3
Remove always true condition `defined(PY_VERSION_HEX)`
XuehaiPan Feb 2, 2026
862aa00
Merge remote-tracking branch 'upstream/master' into fix-py313t
XuehaiPan Feb 3, 2026
24db64d
Detect musllinux
XuehaiPan Feb 3, 2026
c17212a
Add manylinux test
XuehaiPan Feb 3, 2026
3d4af60
Use direct mutex locking for Python 3.13t
XuehaiPan Feb 3, 2026
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Empty commit to trigger CI
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f7a002c
Run apt update before apt install
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Remove unnecessary prefix
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f20f126
Add manylinux test with Python 3.13t
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89b2879
Simplify pycritical_section with std::unique_lock fallback for Python…
XuehaiPan Feb 5, 2026
9a039df
Fix potential deadlock in make_iterator_impl for Python 3.13t
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Merge remote-tracking branch 'upstream/master' into fix-py313t
XuehaiPan Feb 9, 2026
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5 changes: 5 additions & 0 deletions include/pybind11/detail/internals.h
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Original file line number Diff line number Diff line change
Expand Up @@ -245,7 +245,12 @@ class pycritical_section {

public:
explicit pycritical_section(pymutex &m) : mutex(m) {
// PyCriticalSection_BeginMutex was added in Python 3.15.0a1 and backported to 3.14.0rc1
# if defined(PY_VERSION_HEX) && PY_VERSION_HEX >= 0x030E00C1 // 3.14.0rc1
PyCriticalSection_BeginMutex(&cs, &mutex.mutex);
# else
_PyCriticalSection_BeginMutex(_PyThreadState_GET(), &cs, &mutex.mutex);
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@colesbury colesbury Feb 2, 2026

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I don't think this will compile on 3.13 without additional changes. _PyCriticalSection_BeginMutex is in an inline function in an internal-only header (pycore_critical_section.h).

I think we should use PyAPI_FUNC(void) _PyCriticalSection_BeginSlow(PyCriticalSection *c, PyMutex *m); instead. It's not inline, but you'll need to declare it above.

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@colesbury colesbury Feb 2, 2026

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Also, we'll still have the race condition with py::make_key_iterator in 3.13 due to the critical section implementation behaving differently in 3.13, but otherwise it should preserve compatibility.

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@rwgk rwgk Feb 2, 2026

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Also, we'll still have the race condition with py::make_key_iterator in 3.13 due to the critical section implementation behaving differently in 3.13, but otherwise it should preserve compatibility.

I think that's OK. We just want to limp through enough to make the pybind11 v3.0.2 release without breaking what worked with Python 3.13t before.

# endif
}
~pycritical_section() { PyCriticalSection_End(&cs); }

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