id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35059	ASGI server leaves stale DB connections	James Thorniley	James Thorniley	"This seems to be a regression from 4.2 to 5.0.

We are using Django ASGI server via uvicorn, with a mariadb database. When updating our app servers from Django 4.2.8 to 5.0, we experienced a spike in the number of database connections, eventually going over the limit set for the DB and causing 500 errors due to 

`django.db.utils.OperationalError: (1040, 'Too many connections')`

I've created a minimal project to reproduce what I think is the phenomenon here using local docker container for the DB:

https://github.com/jthorniley/django-asgi

I've put complete reproduction steps in that github link, but I will summarise here:

* When running a Django 5.0 ASGI server, some connections are not closed when requests complete, leaving stale connections in the DB. This can be confirmed by running curl against a local server and then `show processlist` in the mysql CLI when the requests are complete.
* As a result, if you send a moderate number of parallel requests to the server, it will go past the limit of DB connections (I think the out-of-the-box limit for the mariadb docker container is around 150, but it is configurable). Then new connections will fail with the `Too many connections` error. Obviously its theoretically possible to go over this limit anyway but it happens sooner due to server processes not cleaning up connections after requests complete.
* You can downgrade to 4.2.8 and run the same reproduction project and see that there is no issue there. The DB connections are closed after every individual request and hence provided there aren't more parallel requests than allowed connections to the DB you are safe.

"	Bug	closed	HTTP handling	5.0	Release blocker	fixed		Carlton Gibson Andrew Godwin	Ready for checkin	1	0	0	0	0	0