multiple async web frameworks in venv breaks aiohttp Server run

[atomscaler]

Hello,

Thank you for this amazing library.

Just a wee heads up I spotted a small issue.

Initially, I was running my socketio.AsyncServer perfectly fine like so:

import socketio
from aiohttp import web

sio = socketio.AsyncServer(async_mode='aiohttp')
app = web.Application()
sio.attach(app)

# event handlers and  stuff here...

if __name__ == '__main__':
    web.run_app(app)

then, in the same venv, for another thing (i was just experimenting) I pip installed eventlet.

With no changes to the above code at all, i then got the error posted at the end. My server wouldn not run.

After some head scratching, I tried installing eventlet, and the error went away.

Conscious having two async web frameworks in one venv may be bad practice, however the param async_mode='aiohttp' i guess implies you can force one to be selected.

It just surprised me that even having eventlet in my venv caused this error.

Many thanks

bus % python bus.py
Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/selector_events.py", line 261, in _add_reader
    key = self._selector.get_key(fd)
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/selectors.py", line 193, in get_key
    raise KeyError("{!r} is not registered".format(fileobj)) from None
KeyError: '5 is not registered'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/benjamindyer/fh/ptarmigan/src/bus/bus.py", line 43, in <module>
    web.run_app(app)
  File "/Users/benjamindyer/fh/ptarmigan/ptarmigan-venv/lib/python3.9/site-packages/aiohttp/web.py", line 479, in run_app
    loop = asyncio.get_event_loop()
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/events.py", line 639, in get_event_loop
    self.set_event_loop(self.new_event_loop())
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/events.py", line 659, in new_event_loop
    return self._loop_factory()
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/unix_events.py", line 54, in __init__
    super().__init__(selector)
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/selector_events.py", line 61, in __init__
    self._make_self_pipe()
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/selector_events.py", line 112, in _make_self_pipe
    self._add_reader(self._ssock.fileno(), self._read_from_self)
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/selector_events.py", line 263, in _add_reader
    self._selector.register(fd, selectors.EVENT_READ,
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/selectors.py", line 523, in register
    self._selector.control([kev], 0, 0)
TypeError: changelist must be an iterable of select.kevent objects
Exception ignored in: <function BaseEventLoop.__del__ at 0x1091fd700>
Traceback (most recent call last):
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/base_events.py", line 683, in __del__
    self.close()
  File "/usr/local/Cellar/python@3.9/3.9.5/Frameworks/Python.framework/Versions/3.9/lib/python3.9/asyncio/unix_events.py", line 63, in close
    if self._signal_handlers:
AttributeError: '_UnixSelectorEventLoop' object has no attribute '_signal_handlers'

[miguelgrinberg]

I can't reproduce this. I have a venv with all the frameworks installed, and aiohttp does not appear to have a collision with eventlet. I can run the aiohttp server example in this repo with and without the async_mode option set and both work fine.

The error that you have could indicate that you have monkey patched the standard library for eventlet, which will definitely prevent any asyncio app from running.

[miguelgrinberg]

@FifthHour I definitely welcome all reports of possible bugs. This problem you are seeing is definitely something that I wouldn't want to ignore, but given that I cannot reproduce it myself, maybe it would be a good idea if you can come up with a simple example that shows this problem. If you show me the code, the version of Python and the output of pip freeze I think I should be able to figure it out. Thanks!