Example with @socket.io/cluster-engine and Node.js cluster

How to use

# run the server
$ node server.js

# run the client
$ node client.js

Explanation

The server.js script will create one Socket.IO server per core, each listening on the same port (3000).

With the default engine (provided by the engine.io package), sticky sessions would be required, so that each HTTP request of the same Engine.IO session reaches the same worker.

The NodeClusterEngine is a custom engine which takes care of the synchronization between the servers by using the IPC channel and removes the need for sticky sessions when scaling horizontally.