Node.js's "cluster" module usage

server.js

var cluster = require("cluster");
var os = require("os");

var numCPUs = os.cpus().length;

if (cluster.isMaster) {
    // Fork workers.
    for (var i = 0; i < numCPUs; i++) {
      cluster.fork();
    }

    cluster.on('exit', function(worker, code, signal) {
      console.log('worker ' + worker.process.pid + ' died');
    });
    return;
}

// worker logic here...