Streaming request not being canceled when client disconnects

[nbilgrien-hbs]

Since upgrading to fastapi >= 0.115.7, which bumped my Startlette version from 0.38.5 to 0.45.3, no exception (not even the ClientDisconnect) is being raised when I cancel an http 2 streaming request, which is returning a StreamingResponse.

I have a long running task that is an async generator. Inside of that generator, I was previously catching the CancelledError that was raised when the request was canceled in order to do some cleanup work before re-raising the exception. Here is an example of how I was using this:

async def long_running_async_generator():
    try:
        for i in range(10):
            yield i
            await asyncio.sleep(5)
    except CancelledError as e:
        print("cleaning up")
        raise (e)
    except Exception as e:
        print("Other exception found:", e)
        raise(e)

Note that even the other open except clause (catching all other exceptions) is not being triggered either. The for loop would just continue to run.

This is almost certainly related to https://github.com/encode/starlette/pull/2732/files.

[Kludex]

Uvicorn version?

[nbilgrien-hbs]

0.29.0

[Kludex]

Bump it to the latest. It should solve the issue.

[Kludex]

What happened is that Uvicorn was with the wrong asgi_version for some versions, so when I pushed this: https://github.com/encode/starlette/pull/2732/files, I broke some flows.

To be fair, I corrected the issue in Uvicorn first, and waited a bit to add the change to starlette.

[nbilgrien-hbs]

that solved it, thank you for the quick response!