Can't set a non-default event loop when running `adev runserver`

[Vlad George Ardelean]

This is the command that I'm running

adev runserver -v butler/app.py --app-factory create_app --pre-check

..And this is the traceback I get

Process Process-1:
Traceback (most recent call last):
  File "/home/username/.pyenv/versions/3.6.3/lib/python3.6/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/home/username/.pyenv/versions/3.6.3/lib/python3.6/multiprocessing/process.py", line 93, in run
    self._target(*self._args, **self._kwargs)
  File "/home/username/work/project/project-venv/lib/python3.6/site-packages/aiohttp_devtools/runserver/serve.py", line 127, in serve_main_app
    loop=loop,
  File "/home/username/work/project/project-venv/lib/python3.6/site-packages/aiohttp/web.py", line 250, in make_handler
    self._set_loop(loop)
  File "/home/username/work/project/project-venv/lib/python3.6/site-packages/aiohttp/web.py", line 128, in _set_loop
    "web.Application instance initialized with different loop")
RuntimeError: web.Application instance initialized with different loop

The problem is that I am instantiating my app like this: app = aiohttp.web.Application(loop=uvloop).
I have no way of making this change the default ioloop policy before a default ioloop is being instantiated.

This is the function that's killing my buzz:

def serve_main_app(config: Config, tty_path: Optional[str], loop: asyncio.AbstractEventLoop=None):
    with set_tty(tty_path):
        setup_logging(config.verbose)

        # THIS IS THE BUZZ-KILLING LINE
        # If only this line was AFTER the current line - but that is circular and can't be done currently.
        # However, if my factory function was loaded before this line was executed, then I'd be very happy :D
        # That would give me the chance to do `asyncio.set_event_loop_policy(uvloop.EventLoopPolicy())`
        loop = loop or asyncio.get_event_loop()

        app = config.load_app(loop)

        modify_main_app(app, config)

        loop.run_until_complete(check_port_open(config.main_port, loop))
        handler = app.make_handler(
            logger=dft_logger,
            access_log_format='%r %s %b',
            loop=loop,
        )

Do you need help with this? I'd gladly import the factory function before retrieving the loop. That could probably make a few people happy.

Thanks!

[Samuel Colvin]

What aiohttp version are you using and what version of aiohttp-devtools?

The loop argument to Application has been deprecated since at least 2.2.

[Vlad George Ardelean]

Hi
I have seen indeed that the argument is deprecated, however even if I'd be calling web.Application() with no loop argument, I'd have the problem that I still wouldn't want to use the default event loop.

I created a PR for this. Please review it, and if it's fine, I'd be very happy if this was integrated and released in some time, at your own leisure :)

Thanks a lot for the cool library!