Who uses Socket IO in production

Maximum simultaneous Socket.IO connections

This question has been asked before but not recently and with no clear answer.

When using Socket.io, is there a maximum number of concurrent connections that can be kept before you need to add another server?

Does anyone know of active production environments where websockets (especially socket.io) are used extensively? I would really like to know what type of setup is best for maximum connections.

Since websockets are based on TCP, I believe they are bound to the 64K port limit as long as the ports are not shared between connections. But I've also seen reports of 512K connections with Gretty. So i don't know.


This article can help you with that: http://drewww.github.io/socket.io-benchmarking/

I asked myself the same question and at the end wrote a little test (with XHR polling) to see when the connections were failing (or falling back). I found (in my case) that the sockets started working around 1400-1800 concurrent connections.

This is a quick recap that I did, similar to the test I used: https://gist.github.com/jmyrland/5535279

I tried using socket.io on AWS. I can hold a maximum of 600 connections stable.

And I found out that it's because socket.io used long queries first and later updated to websocket.

After setting the configuration to only use websocket, I can keep around 9000 connections.

Set this configuration on the client side:

For + 300k simultaneous connection:

Put these variables in:

Also change these variables to:

And finally, increase the TCP buffers as well:

Further information can be found at https://www.linangran.com/?p=547

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