Import application before running the event loop

[Kludex]

• Replaces Import application before running the event loop #1110
• Solves Eventloop running at import time from CLI #346

[graingert]

how does this interact with reload?

[Kludex]

@graingert With the simple application:

import anyio


async def example():
    await anyio.sleep(0)
    print("All good!")


anyio.run(example)


async def app(scope, receive, send):
    pass

Running uvicorn with reload:

(uvicorn3.8.12) ➜  uvicorn git:(feat/import-app-before-event-loop) ✗ uvicorn main:app --reload --port 8005
INFO:     Will watch for changes in these directories: ['/Users/marcelotryle/Development/encode/uvicorn']
INFO:     Uvicorn running on http://127.0.0.1:8005 (Press CTRL+C to quit)
INFO:     Started reloader process [6724] using watchgod
All good!
INFO:     Started server process [6738]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
WARNING:  WatchGodReload detected file change in '['/Users/marcelotryle/Development/encode/uvicorn/main.py']'. Reloading...
INFO:     Shutting down
INFO:     Waiting for application shutdown.
INFO:     Application shutdown complete.
INFO:     Finished server process [6738]
All good!
INFO:     Started server process [6774]
INFO:     Waiting for application startup.
INFO:     Application startup complete.

[euri10]

lgtm thanks @Kludex

[graingert]

I think you should call setup_event_loop as close to asyncio.run as possible

[Kludex]

In other words... 🤔

[Kludex]

I'm not able to reproduce the issue that motivated this PR.

I'm going to close this. If someone wants to try to reproduce, and come back with the proof again, we take a decision then.