tests.patcher_test.test_fork_after_monkey_patch fails on py3.9

[mgorny]

This looks like a regression due to a new test.

$ python3.9 --version
Python 3.9.0rc2

tests.patcher_test.test_fork_after_monkey_patch ... Program /tmp/portage/dev-python/eventlet-0.28.0/work/eventlet-0.28.0/tests/isolated/patcher_fork_after_monkey_patch.py output:
---
Exception ignored in: <function _after_fork at 0x7f2c51f7d430>
Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 1492, in _after_fork
    thread._reset_internal_locks(False)
  File "/usr/lib/python3.9/threading.py", line 827, in _reset_internal_locks
    self._started._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 527, in _at_fork_reinit
    self._cond._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 253, in _at_fork_reinit
    self._lock._at_fork_reinit()
AttributeError: 'Semaphore' object has no attribute '_at_fork_reinit'
Exception ignored in: <function _after_fork at 0x7f2c51f4a670>
Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 1492, in _after_fork
    thread._reset_internal_locks(False)
  File "/usr/lib/python3.9/threading.py", line 827, in _reset_internal_locks
    self._started._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 527, in _at_fork_reinit
    self._cond._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 253, in _at_fork_reinit
    self._lock._at_fork_reinit()
AttributeError: 'Semaphore' object has no attribute '_at_fork_reinit'
Exception ignored in: <function _after_fork at 0x7f2c50813550>
Traceback (most recent call last):
  File "/usr/lib/python3.9/threading.py", line 1486, in _after_fork
    thread._reset_internal_locks(True)
  File "/usr/lib/python3.9/threading.py", line 827, in _reset_internal_locks
    self._started._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 527, in _at_fork_reinit
    self._cond._at_fork_reinit()
  File "/usr/lib/python3.9/threading.py", line 253, in _at_fork_reinit
    self._lock._at_fork_reinit()
AttributeError: 'Semaphore' object has no attribute '_at_fork_reinit'
Traceback (most recent call last):
  File "/tmp/portage/dev-python/eventlet-0.28.0/work/eventlet-0.28.0/tests/isolated/patcher_fork_after_monkey_patch.py", line 42, in <module>
    check(1, threading, 'child post-fork patched')
  File "/tmp/portage/dev-python/eventlet-0.28.0/work/eventlet-0.28.0/tests/isolated/patcher_fork_after_monkey_patch.py", line 7, in check
    assert len(mod._active) == n, 'Expected {} {} threads, got {}'.format(n, tag, mod._active)
AssertionError: Expected 1 child post-fork patched threads, got {139828348036928: <_MainThread(MainThread, stopped 139828348036928)>, 139828306105792: <Thread(patched, started 139828306105792)>, 139828330865232: <_MainThread(MainThread, started 139828330865232)>}
pass

---
FAIL

[ziddey]

Seeing this on starting gunicorn with eventlet as well. Doesn't seem to have broken anything as far as I can tell.

python 3.9.0, eventlet 0.28.0

[temoto]

@tipabu ideas?

[temoto]

On surface it seems eventlet Semaphore must implement new API _at_fork_reinit, relevant to general 3.9 support besides #611

[ziddey]

Took a cursory look as well. Relevant lines:

_thread.Lock._at_fork_reinit() implementation: https://github.com/python/cpython/blob/3.9/Modules/_threadmodule.c#L210

should be fine to call self.__init__(1)? Seems to be working here.

Note threading.Semaphore doesn't have an _at_fork_reinit method

[aescobar-icc]

downgrade to python 3.8 works for me

[4383]

Hello,

I think this bug is now fixed, please can you check with the latest eventlet versions and confirm if you still reproduce the issue. I do not observe similar issue on my side.

Thanks in advance.