Nodejs cluster example

master.js

var cluster = require('cluster');
var numCPUs = require('os').cpus().length;
if(cluster.isMaster) {
    console.log('run master, cpus:', numCPUs);
     // Fork workers.
     function forkWorkers() {
         for (var i = 0; i < numCPUs; i++) {
             var worker = cluster.fork();
             worker.on('message', function(msg) {
                     console.log('on message', msg);
                     if(msg.cmd == 'reloadAll') {
                         console.log('reloadAll');
                         killWorkers();
                         forkWorkers();
                     }
             });
         }
     }
     function killWorkers() {
         for (var i = 0; i < cluster.workers; i++) {
             cluster.workers[i].kill();
         }
     }
     forkWorkers();
     cluster.on('exit', function(worker, code, signal) {
             console.log('worker ' + worker.process.pid + ' died');
     });
} else {
    // workers function
    // require('./server')
    require('./app').listen(3000);
}