Node.js cluster module with Socket.IO

app.js

/**
 * Module dependencies.
 */

var express = require('express')
  , routes = require('./routes')
  , socket = require('socket.io')
  , RedisStore = socket.RedisStore
  , cluster = require('cluster');

var app = module.exports = express.createServer();

// Configuration

app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(__dirname + '/public'));
app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));

/**
 * Handle `request` event.
 */

app.on('request', function(req, res) {
  if (!req.url.match(/^\/socket\.io\/1/)) {
    return;
  }
  console.log('*** request ***');
  console.log('handle request on %s', process.env.NODE_WORKER_ID || process.pid);
  console.log({ handshaken: io.handshaken, open: io.open, connected: io.connected });
});

/**
 * Handle `upgrade` event.
 */

app.on('upgrade', function(req, res) {
  console.log('*** upgrade ***');
  console.log('handle upgrade on %s', process.env.NODE_WORKER_ID || process.pid);
  console.log(req.url);
  console.log(req.headers);
  console.log({ handshaken: io.handshaken, open: io.open, connected: io.connected });
});

// Routes

app.get('/', routes.index);

if (!process.env.NODE_WORKER_ID) {
  
  var io = socket.listen(app, { store: new RedisStore() })
    , handleClient = io.handleClient;
  
  /**
   * Configure Socket.IO
   */
  
  io.set('transports', ['websocket']);

  /**
   * Hook `handleClient` method.
   */
  
  io.handleClient = function(data, req) {
    console.log('*** handleClient ***');
    console.log(data);
    handleClient.apply(io, arguments);
  };
  
  io.sockets.on('connection', function(client) {
    var timerId = setInterval(function() {
      client.emit('ping', process.env.NODE_WORKER_ID || process.pid);
    }, 1000);
  });
  
  /**
   * Boot.
   */

  app.listen(process.env.PORT || 3000);
  console.log("Express server listening on port %d in %s mode", app.address().port, app.settings.env);
}

cluster.js

/**
 * Module dependencies.
 */

var cluster = require('cluster')
  , app = require('./app');

/**
 * Set number of worker process.
 * Default is number of CPUs.
 */

var workers = process.env.WORKERS || require('os').cpus().length;

/**
 * Start cluster.
 */

if (cluster.isMaster) {

  /**
   * Fork process.
   */
  
  console.log('start cluster with %s workers', workers);
  
  for (var i = 0; i < workers; ++i) {
    var worker = cluster.fork();
    console.log('worker %s started.', worker.pid);
  }
  
  /**
   * Restart process.
   */
  
  cluster.on('death', function(worker) {
    console.log('worker %s died. restart...', worker.pid);
    cluster.fork();
  });
} else {
  
  /**
   * Start worker.
   */
  
  app.listen(process.env.PORT || 3000);
}

no such a thing as on('death') http://nodejs.org/api/cluster.html
perhaps you mean disconnect / exit?