Graceful server shutdown

[genericmoniker]

When running the server in a terminal and sending Ctrl+C, it logs:

2021-03-13 09:11:51,204 INFO:     uvicorn.error -> Shutting down
2021-03-13 09:11:51,312 INFO:     uvicorn.error -> Waiting for connections to close. (CTRL+C to force quit)

I had hoped to have clean shutdown using hooks to cancel active tasks and return from any SSE event handlers:

    application = Starlette(
        debug=True,
        routes=routes,
        on_startup=[plugins.startup],
        on_shutdown=[plugins.shutdown, event_bus.shutdown],
    )

But per the documentation:

The shutdown handlers will run once all connections have been closed, and any in-process background tasks have completed.

So it is bad timing. The on_shutdown functions won't get called until the things they are trying to do are already done. What I really need is a hypothetical before_shutdown hook that gets called when starting the shutdown process. There is a feature request for that in Starlette.

This SO question is the same problem, but with websockets: https://stackoverflow.com/questions/58133694/graceful-shutdown-of-uvicorn-starlette-app-with-websockets

The best answer so far has monkey-patching uvicorn's signal handling, which is pragmatic but not very elegant.