^{Originally posted by peterschutt April 5, 2024}
If the shutdown failure message isn't initiated by the app receiving a "lifespan.shutdown" from uvicorn, then the app continues to run after the "lifespan.shutdown.failure" message is received.

Reproducer:

import asyncio
import contextlib
from collections.abc import AsyncIterator

import anyio
import uvicorn
from starlette.applications import Starlette
from starlette.responses import JSONResponse
from starlette.routing import Route


async def homepage(_) -> JSONResponse:
    return JSONResponse({'hello': 'world'})


async def sleep_and_raise() -> None:
    await asyncio.sleep(1)
    raise RuntimeError("An error occurred")


@contextlib.asynccontextmanager
async def lifespan(_: Starlette) -> AsyncIterator[None]:
    async with contextlib.AsyncExitStack() as stack:
        tg = await stack.enter_async_context(anyio.create_task_group())
        tg.start_soon(sleep_and_raise)
        yield


app = Starlette(debug=True, routes=[Route('/', homepage)], lifespan=lifespan)


if __name__ == "__main__":
    uvicorn.run(app, lifespan="on")

After the error occurs in the lifespan task, the app continues to serve:

Given that apps like starlette and litestar encourage use of the lifespan context for orchestration of things that should have a lifespan equivalent to the application object, then I think it would make sense for the app to stop if something has failed within that lifespan after the app has sent "startup.complete" but before the server has sent "shutdown" to the app.

The spec seems to agree:

If a server sees this it should log/print the message provided and then terminate.

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