Optimal nginx settings for websockets sending images

[Maxim Dounin]

Hello!

On Mon, Feb 25, 2013 at 10:15:55PM -0500, michael.heuberger wrote:

> The recent nginx 1.3.13 websocket support is fantastic! Big thanks to the
> nginx devs, it works like a charm.

Good to hear.  :)

> I only have performance issues. Sending images through websockets turns out
> to be difficult and slow. I have a website sending 5 images per seconds to
> the server.
> 
> Sometimes I have warnings like "an upstream response is buffered to a
> temporary file", then sometimes it's lagging and the server isn't that
> fast.

This messages are not related to websocket connections, as 
websocket connections doesn't do any disk buffering and only use 
in-memory buffers.  (More specifically, a connection uses two 
in-memory buffers with size of proxy_buffer_size - one for 
backend-to-client data, and one for client-to-backend data.)

Given the above, I would suppose that you actually have 
performance problems unrelated to websockets.

> I'm not sure if my settings for this scenario are optimal. Below you will
> find extracts of my nginx conf files. Maybe you spot some mistakes or have
> suggestions?

[...]

>         proxy_buffers 8 2m;
>         proxy_buffer_size 10m;
>         proxy_busy_buffers_size 10m;

Buffers used looks huge, make sure you have enough memory.

>         proxy_cache one;
>         proxy_cache_key "$request_uri|$request_body";

Usuing request body as a cache key isn't really a good idea unless 
all request bodies are known to be small.

[...]

-- 
Maxim Dounin
http://nginx.com/support.html