purple-explorer/bin/cluster

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

if (cluster.isMaster) {
  fs.writeFile('./tmp/cluster.pid', process.pid.toString(), function (err) {
    if (err) {
      console.log('Error: unable to create cluster.pid');
      process.exit(1);
    } else {
      console.log('Starting cluster with pid: ' + process.pid);

      // ensure workers exit cleanly
      process.on('SIGINT', function() {
        console.log('Cluster shutting down..');

        for (var id in cluster.workers) {
          console.log('Worker shutting down (' + id + ')');
          cluster.workers[id].kill();
        }

        // exit the master process
        process.exit(0);
      });

      // count the machine's CPUs
      var cpuCount = require('os').cpus().length;

      // create a worker for each CPU
      for (var i = 0; i < cpuCount; i += 1)
        cluster.fork();

      // listen for dying workers
      cluster.on('exit', function (worker, code, signal) {
        if (worker['process']['exitCode'] === 0)
          console.log('Worker shut down.');
        else if ((signal != 'SIGINT') && (worker['process']['exitCode'] !== 0) && (worker.exitedAfterDisconnect !== true)) {
          console.log('Cluster restarting...');
          cluster.fork();
        }
      });
    }
  });
} else
  require('./instance');