node/doc/api/cluster.markdown

Cluster

A single instance of Node runs in a single thread. To take advantage of multi-core systems the user will sometimes want to launch a cluster of Node processes to handle the load.

The cluster module allows you to easily create a network of processes all which share server ports.

var cluster = require('cluster'); var http = require('http');

if (!cluster.isWorker()) { // Start the master process, fork workers. cluster.startMaster({ workers: 2 }); } else { // Worker processes have a http server. http.Server(function(req, res) { res.writeHead(200); res.end("hello world\n"); }).listen(8000); }

If we start it like this

% node cluster server.js 
Detected 2 cpus
Worker 2438 online
Worker 2437 online

Node will automatically share port 8000 between the multiple instances.