bpo-42972: Fix GC assertion error in _winapi by untracking Overlapped earlier

[Fidget-Spinner]

See #26381 (comment). This untracks a possible 'bad' object earlier so the GC stops having weird race conditions. Fixes a gc assertion error in debug mode in test_httplib.

python_d.exe -m test test_httplib -m test_local_bad_hostname ...\cpython\Modules\gcmodule.c:446: update_refs: Assertion "gc_get_refs(gc) != 0" failed Enable tracemalloc to get the memory block allocation traceback object address : 000002DADE2A99D0 object refcount : 0 object type : 000002DADDF72F60 object type name: _winapi.Overlapped object repr : <refcnt 0 at 000002DADE2A99D0> Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed Python runtime state: initialized 

https://bugs.python.org/issue42972

[Fidget-Spinner]

@vstinner seems like your gut feeling about UnTrack was right

[vstinner]

test_httplib doesn't use asyncio, so it's unrelated. The test_httplib crash is: https://bugs.python.org/issue44252

python_d.exe -m test test_httplib -m test_local_bad_hostname ...\cpython\Modules\gcmodule.c:446: update_refs: Assertion "gc_get_refs(gc) != 0" failed Enable tracemalloc to get the memory block allocation traceback 

[vstinner]

If you want to modify overlapped_dealloc(), I suggest to also remove the compatibility code for Windows XP.

 if (self->pending){if (check_CancelIoEx() && Py_CancelIoEx(self->handle, &self->overlapped) && GetOverlappedResult(self->handle, &self->overlapped, &bytes, TRUE)){/* The operation is no longer pending -- nothing to do. */ } else if (_Py_IsFinalizing()){/* The operation is still pending -- give a warning. This will probably only happen on Windows XP. */ PyErr_SetString(PyExc_RuntimeError, "I/O operations still in flight while destroying " "Overlapped object, the process may crash"); PyErr_WriteUnraisable(NULL)} else{/* The operation is still pending, but the process is probably about to exit, so we need not worry too much about memory leaks. Leaking self prevents a potential crash. This can happen when a daemon thread is cleaned up at exit -- see #19565. We only expect to get here on Windows XP. */ CloseHandle(self->overlapped.hEvent); SetLastError(err); return} } 

check_CancelIoEx() can be removed and CancelIoEx() can be used directly. It's available since Windows Vista and Python 3.11 requires Windows Vista or newer:
https://docs.microsoft.com/en-us/windows/win32/fileio/cancelioex-func

See also bpo-32592 "Drop support of Windows Vista and Windows 7".

Please open a separated PR for that.

I don't think that it's worth it to only move the PyObject_GC_UnTrack() call.

[Fidget-Spinner]

test_httplib doesn't use asyncio, so it's unrelated. The test_httplib crash is: https://bugs.python.org/issue44252

python_d.exe -m test test_httplib -m test_local_bad_hostname ...\cpython\Modules\gcmodule.c:446: update_refs: Assertion "gc_get_refs(gc) != 0" failed Enable tracemalloc to get the memory block allocation traceback 

Sorry, I was referring to another crash. These 2 build bots crashed when running in python debug mode due to my previous commit:
https://buildbot.python.org/all/#/builders/146/builds/294/steps/4/logs/stdio
https://buildbot.python.org/all/#/builders/596/builds/323/steps/4/logs/stdio

Both due to assertion errors in the GC. So I wanted to fix those first. The Windows support ones can come another time.

[vstinner]

Sorry, I was referring to another crash. These 2 build bots crashed when running in python debug mode due to my previous commit:

Ah ok, I merged your PR.

[vstinner]

Can you please create a 3.10 backport which contains your two commits? Use git cherry-pick -x.

[vstinner]

I closed #26431 which only contained the first fix.

[Fidget-Spinner]

Can you please create a 3.10 backport which contains your two commits? Use git cherry-pick -x.

Yep, #26430 has both fixes. Thanks!