Django 5.1, ASGI, SSE

[mamashin]

Hello.

Sorry, I have a question about Django and ASGI. I saw that a similar topic has already been discussed, but I couldn't find a solution for myself.

Unit 1.33
Django 5.1 (support async handling disconnects)
Python 3.11.2
Debian 12

Test Django code:

def sse(request: HttpRequest) -> HttpResponseBase:
    """Small demo of the basic idea of SSE without any redis or other complexity"""
    async def stream(request: HttpRequest) -> AsyncGenerator[str, None]:
        try:
            counter = 0
            while True:
                counter += 1
                if counter != 1:
                    await asyncio.sleep(1.0)
                yield f"data: <div>{counter}</div>\n\n"
        except asyncio.CancelledError:
            logger.debug("SSE Client disconnected")
            raise

    return StreamingHttpResponse(
        streaming_content=stream(request),
        content_type="text/event-stream"
    )

When I run this code under the Uvicorn ASGI server, after closing the connection, I see "SSE Client disconnected" in my dubug log. However, under Unit, nothing happens, with only in unit log:

2024/12/01 11:29:31 [info] 40085#40121 *11 writev(44, 2) failed (32: Broken pipe)

It seems that Django does not detect that the connection is closed, and this is only apparent when I restart Unit. In the logs:

2024/12/01 11:02:55 [warn] 34253#34253 [unit] #516: active request on ctx quit
2024/12/01 11:02:55 [warn] 34253#34253 [unit] #404: active request on ctx free

In a production environment when I use Redis, I see many connections with Unit and Redis in the ESTABLISHED state, even though many connections are already closed. This is a problem for me.

What am I doing wrong 🤔 ?

[mamashin]

small addon.

this is my debug ASGI entry point:

import os
from loguru import logger
from django.core.asgi import get_asgi_application

os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'conf.settings')
django_application = get_asgi_application()

async def application(scope, receive, send):
    if scope['type'] == 'http':
        # Let Django handle only ASGI HTTP requests
        async def receive_wrapper():
            message = await receive()
            logger.debug(f'ASGI application receive message: {message}')
            await logger.complete()
            return message
        await django_application(scope, receive_wrapper, send)
    else:
        pass

When I connected, I see:

ASGI application receive message: {'type': 'http.request'}

But when I disconnected - log is empty.

As I said, if I run this test under Uvicorn, I see:

ASGI application receive message: {'type': 'http.disconnect'}

Where I lost 'http.disconnect' while working with Unit ?