On 2025-04-06 14:32, dwes1--- via Cygwin wrote:
To the Python maintainer and anyone else testing Python 3.12:
A few weeks ago, the python developer requested help with evaluating the Python
3.12 release.
I downloaded the python312-test package, and worked out that
python -m test.test_threading -v
failed during the second test in the file, sometimes with an immediate segfault,
sometimes by hanging
until I tried to attach gdb, which immediately reported an empty stack and a
null stack pointer.
Adding print calls to the test narrowed the point of failure to some time during
thread cleanup,
so I ran the test under gdb, adding breakpoints to pthread_exit and
pthread::exit, which caught
the test before the segfault, and displayed a stack working back to
pthread_wrapper, whose caller
was set to null. Stepping through the function eventually reached a call to
ExitThread, then the
segfault with no reported stack.
My current guess is that ExitThread somehow returns, leading to control falling
off the end of
pthread_wrapper and failing to return. (This is rather more sensible than my
previous guess
that Python had somehow managed to call the NULL pointer recursively, and not
noticed until
gdb took a look at things) I suppose I could try to compile Cygwin with an
error message after
ExitThread to see if that prints, but I am otherwise out of ideas.
I first checked this around January on a Windows 10 machine from 2016, then on a
machine from
within the last year that is says it is also Windows 10.
I hope this helps
Thanks for helping!
Have you tried running under strace and looking at the output from:
$ strace -o python-312-test-threading.strace python -m test.test_threading -v
or
$ strace -o python-312-test-threading-hung.strace -p PID
--
Take care. Thanks, Brian Inglis Calgary, Alberta, Canada
La perfection est atteinte Perfection is achieved
non pas lorsqu'il n'y a plus rien à ajouter not when there is no more to add
mais lorsqu'il n'y a plus rien à retrancher but when there is no more to cut
-- Antoine de Saint-Exupéry
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