too many file descriptors in select() with NGINX on Windows

[mhdaouas]

I have a Vue 2 SPA app which opens several websocket connections upon mounting specific components and closes them when the user leaves those components (during their destruction) or in other words when accessing/leaving specific pages.

The app is served with a NGINX server on a Windows Server 2016 VM.

An instance of Daphne runs with the following command:
daphne -b <VM IP adress> -p <port> <django app>

It looks like I need to optimize my code and avoid opening and closing the same websockets each time I access/leave specific pages of the app.

I noticed that each time a connection is opened, a new incremented port is opened (I start with 8443 and reach ports like 15078).

After some time Daphne crashes with the following Python error message:
too many file descriptors in select()

Is there a way to force opening the same port for each websocket at least (each "URL") instead of using a new one for the same websocket or any way to limit file descriptor usage?

I saw also that there is a possibility to run several Daphne instances. Can this method resolve my issue ? If yes, how to implement it with NGINX?

Thank you for your kind support.

[carltongibson]

Hi. There's not really enough to go in here but first step would be to check and raise the open file descriptor limit.

Then it would be look into whether sockets are being closed. How many connections are open are once? If you have regular disconnects shouldn't that balance? Etc. 🤔

This isn't really something Incan help you with directly unless you can pin down an addressable issue...

[mhdaouas]

I have 39 websockets that I keep opening and closing in an erratic way. Maybe I need to open them once after user logs in and keep them in that state because it looks like file descriptors are not freed when I close a websocket.

Also it looks like it is impossible to raise the fd limit in Windows/Python (I couldn't find any way).

[carltongibson]

Also it looks like it is impossible to raise the fd limit in Windows/Python (I couldn't find any way).

I didn't experiment yet but, a quick Google search suggested this: https://stackoverflow.com/a/28212496

[carltongibson]

Some idea of the existing limit, and the progression over time would be interesting to see. If it's just set at 255, it's not much of a surprise to see it being exceeded...