aiorun hangs in wait_for_cancelled_tasks

Thank you for your library, it really enhances the user experience when working with asyncio. But in the course of exploitation we came across the fact that sometimes the program does not stop.

The program does not stop in such a situation

import asyncio
import logging

import aiorun


async def coro_with_exception():
    await asyncio.sleep(0.1)
    raise Exception


async def unstoppable_coro():
    # For some reason one of the tasks does not want to stop
    try:
        while True:
            await asyncio.sleep(0.1)
    except asyncio.CancelledError:
        while True:
            await asyncio.sleep(0.1)


async def main():
    asyncio.create_task(unstoppable_coro())
    asyncio.create_task(coro_with_exception())


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    aiorun.run(
        main(),
        stop_on_unhandled_errors=True,
    )

We see the following logs

ERROR:aiorun:Unhandled exception; stopping loop: 'Task exception was never retrieved'
Traceback (most recent call last):
  File "C:\git\aio_run_example.py", line 9, in coro_with_exception
    raise Exception
Exception
INFO:aiorun:Entering shutdown phase.
INFO:aiorun:Cancelling pending tasks.
INFO:aiorun:Running pending tasks till complete

I propose to introduce a correction.

Replace

async def wait_for_cancelled_tasks():
    return await gather(*tasks, *do_not_cancel, return_exceptions=True)

To

async def wait_for_cancelled_tasks():
    return await asyncio.wait([*tasks, *do_not_cancel], timeout=gracefull_shutdown_timeout)

And add argument to run

def run(
    coro: "Optional[Coroutine]" = None,
    *,
    loop: Optional[AbstractEventLoop] = None,
    shutdown_handler: Optional[Callable[[AbstractEventLoop], None]] = None,
    shutdown_callback: "ShutdownCallback" = None,
    executor_workers: Optional[int] = None,
    executor: Optional[Executor] = None,
    use_uvloop: bool = False,
    stop_on_unhandled_errors: bool = False,
    gracefull_shutdown_timeout: float = 60
) -> None:
    ...

If a correction is made, the program is guaranteed to stop.

[cjrh]

Thank you for checking. I take your point about None, but I think it would be better to bail out, since that at least shouldn’t happen silently, and then users can change it to a big number if they like. I think your sugges4tion in the report of 60s is a fine default.

Thanks again!

[cjrh]

@samigullinbulat The change is including in v2022.11.1 which I’ve just deployed: https://pypi.org/project/aiorun/