Is watchdog safe to run without GIL?

[tokeefe]

When running watchdog under Python 3.13t (with the GIL disabled), Python re-enables the GIL and prints the following warning

<frozen importlib._bootstrap>:488: RuntimeWarning: The global interpreter 
lock (GIL) has been enabled to load module '_watchdog_fsevents', which has 
not declared that it can run safely without the GIL. To override this behavior and 
keep the GIL disabled (at your own risk), run with PYTHON_GIL=0 or -Xgil=0.

At a glance, some basic watchdog applications seem to run properly with the GIL disabled. I also ran the test suite on macOS, which passed (at least no additional XPASS or warnings)

python3.13t -Xgil=0 -m tox -q -e py
...
163 passed, 10 skipped, 2 xpassed, 1 warning in 92.15s (0:01:32)
py: OK (94.21 seconds)
congratulations :) (94.33 seconds)

P.S. - After a quick search, it looks as though GitHub Actions is actively working on exposing a new Python version 3.13t that will allow developers to run tests with free-threading enabled. I'm not sure if this is available quite yet, but should be close.

[BoboTiG]

I would be more confident to change the C code when it will be possible to run tests on the CI, as you noted 👍

Note that I do not anymore own a Mac machine to work on that stuff, so if you have some C skills, please be my guest :)

[BoboTiG]

Concerned code:

watchdog/src/watchdog_fsevents.c

Lines 381 to 383 in 30bc010

	/* Acquire interpreter lock and save original thread state. */
	PyGILState_STATE gil_state = PyGILState_Ensure();
	saved_thread_state = PyThreadState_Swap(stream_callback_info_ref->thread_state);

watchdog/src/watchdog_fsevents.c

Lines 449 to 451 in 30bc010

	/* Release the lock and restore thread state. */
	PyThreadState_Swap(saved_thread_state);
	PyGILState_Release(gil_state);