Hi everyone,

python-trio sometimes exhibits test failures, as in the following

--8<---------------cut here---------------start------------->8---
=================================== FAILURES ===================================
____________________ test_wait_reapable_fails[open_process] ____________________
[gw15] linux -- Python 3.10.7 /gnu/store/375350pi1l1izgnx6dnsqmg4xjyprx8q-python-wrapper-3.10.7/bin/python

background_process = <function open_process_then_kill at 0x7ffff40fed40>

    @pytest.mark.skipif(not posix, reason="POSIX specific")
    @background_process_param
    async def test_wait_reapable_fails(background_process):
>       old_sigchld = signal.signal(signal.SIGCHLD, signal.SIG_IGN)

trio/tests/test_subprocess.py:449: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

signalnum = <Signals.SIGCHLD: 17>, handler = <Handlers.SIG_IGN: 1>

    @_wraps(_signal.signal)
    def signal(signalnum, handler):
>       handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
E       ValueError: signal only works in main thread of the main interpreter

/gnu/store/91wasjkmy50p8fq0rf9jby80mnmq1fxr-python-3.10.7/lib/python3.10/signal.py:56: ValueError
_______________ test_wait_reapable_fails[run_process in nursery] _______________
[gw15] linux -- Python 3.10.7 /gnu/store/375350pi1l1izgnx6dnsqmg4xjyprx8q-python-wrapper-3.10.7/bin/python

background_process = <function run_process_in_nursery at 0x7ffff40fee60>

    @pytest.mark.skipif(not posix, reason="POSIX specific")
    @background_process_param
    async def test_wait_reapable_fails(background_process):
>       old_sigchld = signal.signal(signal.SIGCHLD, signal.SIG_IGN)

trio/tests/test_subprocess.py:449: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

signalnum = <Signals.SIGCHLD: 17>, handler = <Handlers.SIG_IGN: 1>

    @_wraps(_signal.signal)
    def signal(signalnum, handler):
>       handler = _signal.signal(_enum_to_int(signalnum), _enum_to_int(handler))
E       ValueError: signal only works in main thread of the main interpreter

/gnu/store/91wasjkmy50p8fq0rf9jby80mnmq1fxr-python-3.10.7/lib/python3.10/signal.py:56: ValueError
=========================== short test summary info ============================
FAILED trio/tests/test_subprocess.py::test_wait_reapable_fails[open_process]
FAILED trio/tests/test_subprocess.py::test_wait_reapable_fails[run_process in nursery]
================== 2 failed, 371 passed, 17 skipped in 3.82s ===================
--8<---------------cut here---------------end--------------->8---

Note that I am on Linux 6.8-rc3 currently.  Can anyone reproduce?

Best,
-- 
Josselin Poiret