Even with PR 30454, I can still reproduce the crash on Python 3.9 (randomly, it takes a few attempts to reproduce the crash):
vstinner@DESKTOP-DK7VBIL C:\vstinner\python\3.9>python -X dev win_py399_crash_reproducer.py
Running Debug|x64 interpreter...
exit subinterpreter
exit subinterpreter
exit subinterpreter
Windows fatal exception: access violation
Thread 0x00002230 (most recent call first):
<no Python frame>
Thread 0x00002124 (most recent call first):
File "C:\vstinner\python\3.9\win_py399_crash_reproducer.py", line 13 in doIt
File "C:\vstinner\python\3.9\lib\threading.py", line 910 in run
File "C:\vstinner\python\3.9\lib\threading.py", line 973 in _bootstrap_inner
File "C:\vstinner\python\3.9\lib\threading.py", line 930 in _bootstrap
Current thread 0x000027f0 (most recent call first):
File "C:\vstinner\python\3.9\win_py399_crash_reproducer.py", line 13 in doIt
File "C:\vstinner\python\3.9\lib\threading.py", line 910 in run
File "C:\vstinner\python\3.9\lib\threading.py", line 973 in _bootstrap_inner
File "C:\vstinner\python\3.9\lib\threading.py", line 930 in _bootstrap
Thread 0x00001c18 (most recent call first):
File "C:\vstinner\python\3.9\lib\threading.py", line 312 in wait
File "C:\vstinner\python\3.9\lib\threading.py", line 574 in wait
File "C:\vstinner\python\3.9\lib\threading.py", line 897 in start
File "C:\vstinner\python\3.9\win_py399_crash_reproducer.py", line 19 in <module>