Node.js-socket.io的cluster兼容性

Question

socket.io是node.js中很一个重要的处理websocket的模块，node.js中的cluster模块也很重要，可以充分发挥多核cpu的性能。但是将两者结合在一起使用的时候，却出现了问题。
在使用中发现浏览器（chrome）控制台会爆出WebSocket is closed before the connection is established错误。

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

 if (cluster.isMaster) { 
    console.log('start cluster with %s workers', workers);  
    for (var i = 0; i < workers; ++i) {  
        var worker = cluster.fork().process;  
        console.log('worker %s started.', worker.pid);  
    }   
    cluster.on('exit', function(worker) {   
        console.log('worker %s died. restart...', worker.process.pid);  
        cluster.fork();   
    });  
} else {
    var express = require('express');
    var app = express();
    var server = require('http').createServer(app);
    var io = require('socket.io').listen(server);//socket.io对象

    server.listen(8000);

    io.configure('production', function(){
      io.enable('browser client etag');
      io.set('log level', 1);

      io.set('transports', [
        'websocket'
      , 'flashsocket'
      , 'htmlfile'
      , 'xhr-polling'
      , 'jsonp-polling'
      ]);
    });
    /*
    io.configure('development', function(){
      io.set('transports', ['websocket']);
    });
    */
    app.configure('production',function() {
        app.error(function(err,req,res,next) {
            console.log(err.stack);
            next();
        });
    });

    app.get('/', function (req, res) {
      res.sendfile(__dirname + '/static/index.html');//首页的位置
    });
    app.use('/static', express.static(__dirname + '/static'));//地址static映射static目录

    io.sockets.on('connection', function (socket) {//接收connection事件
      socket.emit('news', { hello: 'world' });//发送news事件
     
      socket.on('add', function (username) {//接收add事件
        console.log(username);
        socket.set('nickname', username, function () {
          socket.emit('ready');//发送ready事件
        });
         io.sockets.emit('online add',username);//向全体用户发送online add事件
      });
      
    });
}