cluster management concept

master.js

'use strict';

var cluster = require('cluster'),
    cpus = require('os').cpus().length;

function single() {
  require('./worker');
}


function master() {
  var nodes = cpus * 4,
      workers = [];

  console.log('starting %d nodes', nodes);


  (function next(index) {
    if (index > nodes) {
      return done();
    }

    console.log('starting %d', index);

    var worker = cluster.fork();

    worker.on('message', function (msg) {
      if (msg.event === 'ready') {
        console.log('%d is up and running', index);
        index++;
        workers.push(worker);
        next(index);
      } else {
        console.log(require('util').inspect(msg, true, 10, true))
      }
    });
  }(1));

  function done() {
    console.log('started %d workers', workers.length);
  }

}

if (cluster.isMaster) {
  master();
} else {
  single();
}

worker.js

'use strict';

// worker

console.log('hi - i\'m a worker');

function wait(fn) {
  setTimeout(fn, 1000);
}

wait(function () {
  console.log('reading lots and lots of files');
  wait(function () {
    console.log('compressing stuff');
    wait(function () {
      console.log('building caches');
      wait(function () {
        console.log('ready');
        process.send({
          event: 'ready',
          pid: process.pid
        });
      });
    });
  });
});