Make force_exit configure-able from command line

[devxpy]

Hello!

In development mode, with --debug, uvicorn waits for background tasks before reloading the server.

This is annoying if the server has background tasks in an infinite loop. You have to manually press Ctrl+C to reload code, which (I think) defeats the whole purpose of having an "automatic" reloader.

 $ uvicorn <app> --debug
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
INFO:     Started reloader process [84365] using statreload
INFO:     Started server process [84367]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
.
.
.
.
WARNING:  Detected file change in '<file>'. Reloading...
INFO:     Shutting down
INFO:     Waiting for background tasks to complete. (CTRL+C to force quit) <--- ???
^CINFO:     Shutting down <--- Ctrl+C

---

As a workaround, I tried setting force_exit = True manually and it seems to work great.

config = uvicorn.Config("<app>", debug=True)
server = uvicorn.Server(config=config)

server.force_exit = True  # <---

sock = config.bind_socket()
supervisor = ChangeReload(config, target=server.run, sockets=[sock])
supervisor.run()

---

Happy to submit a PR adding this as a click option if you think this is a valid concern.

Thanks for this great project and others :)

[jjehl]

I need this option. Could you please explain where you change the force_exit, is it in the source code ?

Edit : it is in uvicorn/main.py

here the code to force reload line 422

if config.should_reload:
    server.force_exit = True 
    sock = config.bind_socket()
    ChangeReload(config, target=server.run, sockets=[sock]).run()

[MatthewScholefield]

Actually, force_exit=True is a straightforward solution but a small detail is that when using this approach we get CancelledError when stopping with ctrl+c because self.lifespan.shutdown isn't called in server.shutdown. So it'd be nice if the override was just for in-progress connections. Like a wait_for_background_tasks=True parameter.

Side note, for anyone launching from Python, I've allowed customizing force_exit here.

[anishjirel123]

INFO Server running on [http://127.0.0.1:8000].

Press Ctrl+C to stop the server why my serve is not stop giving me reason

[Kludex]

What I said on https://github.com/encode/uvicorn/issues/451#issuecomment-1367828755 also solves the issue here.

[Kludex]

If we set --timeout-graceful-shutdown to 0, then this will be achieved. Let's do that. :+1:

[AntonOfTheWoods]

Actually @Kludex , it appears that this doesn't work with the --timeout-graceful-shutdown option - is there any official way to have this yet?

[gauravg713]

Question to this, I am getting "INFO: Waiting for background tasks to complete. (CTRL+C to force quit)" on logs in cloud run . I am using background task with fastapi. I am not getting why this shutdown happening and how we can check which background task is blocking the process. Can anyone help please ?