pytest-aiohttp + pytest-xdist cause RuntimeError: set_wakeup_fd only works in main thread #3450
Description
Long story short
Combining pytest-aiohttp and pytest-xdist an error is triggered sometimes from the loop fixture.
Let me know if you think the issue is more on the pytest(-xdist) side.
Expected behaviour
No error.
Actual behaviour
=================================================================================================================== ERRORS ====================================================================================================================
_____________________________________________________________________________________________________ ERROR at setup of test_foo[pyloop] ______________________________________________________________________________________________________
[gw6] linux -- Python 3.7.0 /home/merlin/workspace/pytest-test/.venv/bin/python3.7
loop_factory = <class 'asyncio.unix_events._UnixDefaultEventLoopPolicy'>, fast = False, loop_debug = False
@pytest.fixture
def loop(loop_factory, fast, loop_debug):
"""Return an instance of the event loop."""
policy = loop_factory()
asyncio.set_event_loop_policy(policy)
> with loop_context(fast=fast) as _loop:
.venv/lib/python3.7/site-packages/aiohttp/pytest_plugin.py:205:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
/usr/local/lib/python3.7/contextlib.py:112: in __enter__
return next(self.gen)
.venv/lib/python3.7/site-packages/aiohttp/test_utils.py:404: in loop_context
loop = setup_test_loop(loop_factory)
.venv/lib/python3.7/site-packages/aiohttp/test_utils.py:427: in setup_test_loop
watcher.attach_loop(loop)
/usr/local/lib/python3.7/asyncio/unix_events.py:868: in attach_loop
loop.add_signal_handler(signal.SIGCHLD, self._sig_chld)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
self = <_UnixSelectorEventLoop running=False closed=False debug=False>, sig = <Signals.SIGCHLD: 17>, callback = <bound method BaseChildWatcher._sig_chld of <asyncio.unix_events.SafeChildWatcher object at 0x7fbf10c9b048>>, args = ()
def add_signal_handler(self, sig, callback, *args):
"""Add a handler for a signal. UNIX only.
Raise ValueError if the signal number is invalid or uncatchable.
Raise RuntimeError if there is a problem setting up the handler.
"""
if (coroutines.iscoroutine(callback) or
coroutines.iscoroutinefunction(callback)):
raise TypeError("coroutines cannot be used "
"with add_signal_handler()")
self._check_signal(sig)
self._check_closed()
try:
# set_wakeup_fd() raises ValueError if this is not the
# main thread. By calling it early we ensure that an
# event loop running in another thread cannot add a signal
# handler.
signal.set_wakeup_fd(self._csock.fileno())
except (ValueError, OSError) as exc:
> raise RuntimeError(str(exc))
E RuntimeError: set_wakeup_fd only works in main thread
/usr/local/lib/python3.7/asyncio/unix_events.py:94: RuntimeError
===================================================================================================== 10 passed, 1 error in 0.93 seconds ======================================================================================================
Steps to reproduce
I've copied the same test file 10 times (just to have some tests to work with).
async def test_foo(loop):
assert 42 == 42I use bash in order to run pytest several times until it fails:
while pytest tests/ -n auto -v; do :; doneNot sure why, but the verbose flag seems to affect it: -v
Your environment
Tested on 3.6 and 3.7.
8 Cores CPU
Python 3.6.7
Python 3.7.0b5
aiohttp==3.4.4
pytest==4.0.1
pytest-aiohttp==0.3.0
pytest-xdist==1.25.0