How to handle 20k concurrent listeners on an Icecast server

Question

I want to know how to handle more than 20k listeners concurrently on an Icecast server. I am using liquidsoap as the audio stream generator (Only one audio stream is distributed through the Icecast server ). The server is configured on AWS. Further, I want to know whether I need to use LB and CDN to handle this much traffic.

Answer 1

Your main concern is bandwidth. Nothing else, bandwidth. You always run out of bandwidth first. Really.

You'll likely want to spread the load across multiple servers and e.g. do simple DNS round-robin. Also because multiple servers means more bandwidth available.

Feeding in a Primary+Relays (master/slave) topology is typical and documented. For more details I'd recommend the Icecast documentation and searching the Icecast mailing list archives.

There are some minor things like making sure that your ulimit for file descriptors is high enough for the Icecast process.

PS: In theory you can squeeze around 20k concurrent connections out of Icecast, but most of the time you won't have enough actual bandwidth to feed those anyway.