Django Channels memory leaks on opening new connections

Hello! First of all, this is a great project and I wanted to thank all the maintainers for keeping it amazing!

For last two months, django-channels websockets on our production service have been periodically failing with OOM. Having researched it, it looks like a django-channels memory leak.

I think it may be related to opening new channel connections and then improperly closing them in channels_layer object. Opening multiple browser tabs leading to a single channels group increases memory usage, and closing them does not release the memory (the disconnect occurs though).

I have also managed to reproduce it on a simple project with minimal dependencies and steps to reproduce, so please feel free to check it out: https://github.com/yuriymironov96/django-channels-leak. This is a project based on django-channels tutorial.

Here are dependencies of the sample project:

• python = “^3.8”
• channels = “^3.0.3”
• channels-redis = “^3.2.0”
• channels-rabbitmq = “^3.0.0”
• Pympler = “^0.9”
• daphne = “^3.0.2”

I have tries both channels_redis and channels_rabbitmq, multiple servers (django debug server, daphne, uvicorn) and the issue still persists.

The sample benchmarks are:

• Server is launched, no browser tabs open: 49.3 MB;
• First browser tab opened: 51.2 MB;
• 20 browser tabs opened: 52.2 MB;
• All browser tabs closed: 52.2 MB;
• 20 browser tabs opened: 52.6 MB;
• All browser tabs closed: 52.6 MB;

It may look like a minor leak at this rate, but it is scales quickly and occurs frequently due to high load of our application.

Could you please have a look at it and share any ideas you have?

[revoteon]

After a week of usage of Uvicorn instead Daphne in production environment, I’m now fully convinced that this leak is related to Daphne, not channels. In my use case, results are significant:

Not only that, the switch to Uvicorn proved to have significant effect on CPU usage as well. Its lower than that of Daphne. As a result, we have not only addressed memory leak, but also improved website performance as well.

[ax003d]

same here, it works well with python3.6, but when I upgrade to python3.8, Daphne began memory leak. I have these packages installed: channels==2.4.0 channels-redis==3.1.0