Destructing `_datetime` in sub-interpreters in the same time may crash the process

[aisk]

Crash report

What happened?

from concurrent.futures import InterpreterPoolExecutor


executor = InterpreterPoolExecutor()


def f():
    import _datetime
    print(_datetime)


executor.submit(f)
executor.submit(f)

executor.shutdown()

This code may lead to a interpreter crash:

PS C:\Users\xxxxx\Source\cpython> .\python.bat .\a.py
Running Debug|x64 interpreter...
<module '_datetime' (built-in)>
<module '_datetime' (built-in)>
Debug memory block at address p=000002340D505A70: API '?
    15987178197214944733 bytes originally requested
    The 7 pad bytes at p-7 are not all FORBIDDENBYTE (0xfd):
        at p-7: 0xdd *** OUCH
        at p-6: 0xdd *** OUCH
        at p-5: 0xdd *** OUCH
        at p-4: 0xdd *** OUCH
        at p-3: 0xdd *** OUCH
        at p-2: 0xdd *** OUCH
        at p-1: 0xdd *** OUCH
    Because memory is corrupted at the start, the count of bytes requested
       may be bogus, and checking the trailing pad bytes may segfault.
    The 8 pad bytes at tail=DDDDE011EB2E384D are

I think there is a double free here.

Please note that there is a similar issue may crash the interpreter but in the initializing phase: #136421

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS, Windows

Output from running 'python -VV' on the command line:

Python 3.15.0a0 (heads/main:ba9c1986305, Jul 8 2025, 22:13:18) [MSC v.1943 64 bit (AMD64)]

[aisk]

cc @ericsnowcurrently

[seuwebber]

I encountered the same bug while using the C Python API.