Demonstrates bug in NodeJS 'net' module under clustering

net-no-cluster-good.js

/**
 * This demonstrates how server.listen with port set to zero
 * does not function properly in a cluster environment.
 *
 * EXPECTED RESULT: each worker's server starts listening on a
 * unique port as per documentation "A port value of zero will assign a random port."
 *
 * ACTUAL DEMONSTRATED RESULT: each worker's server starts listening
 * on the exact same port as every other worker.
 */
"use strict";

var cluster = require('cluster')
  , net = require('net')
  , numForks = 5
  , i
  ;

if (cluster.isMaster) {
  // fork workers
  for (i = 0; i < numForks; ++i) {
    cluster.fork();
  }
} else {
  // worker code - create variable scope with executed function
  (function() {
    var server = net.createServer();
    /** 
     * server.listen(port, [host], [listeningListener])
     * Begin accepting connections on the specified port and host. If the host 
     * is omitted, the server will accept connections directed to any IPv4 address 
     * (INADDR_ANY). A port value of zero will assign a random port.
     */
    server.listen(0);
    server.on('listening', function() {
      var address = server.address()
        , port = address.port
        ;

      console.log(port);      
    });
  })();
}