Bug report

Bug description:

I mentioned regex but this probably applies to other modules as well. In the code below, if the # line right after the findall is commented out (as it is right now), the code raises the exception past the try-except block on the print("Safely reached EOF.") statement. The exception happens one statement later than expected. NB: I tested all Python versions on Windows but only 3.11 on Linux.

import _thread, re
from threading import Timer

s = "ab"*20000000
pattern = re.compile("ab+")
Timer(0.2, _thread.interrupt_main).start()
try:
    pattern.findall(s)
#    print() ###################################################################
except:
    print("Exception block")
print("Safely reached EOF.")

CPython versions tested on:

3.9, 3.10, 3.11, 3.12, CPython main branch

Operating systems tested on:

Linux, Windows

Linked PRs

• gh-109631: Allow interruption of short repeated regex matches #109867
• [3.11] gh-109631: Allow interruption of short repeated regex matches (GH-109867) #109885
• [3.12] gh-109631: Allow interruption of short repeated regex matches (GH-109867) #109886