Node.js

https://www.npmjs.org/package/async

var async = require('async');
var queue = async.queue(worker, 40);
queue.push(ip);
queue.drain = function() {
  console.log("all done");
}
 
function worker (host, callback) {
  console.log("Hard Working");
  for(var i = 0; i <= 5; i++) {
    if(i == 5) 7
      callback();
    }  
  }  
}

https://www.npmjs.org/package/socket.io

server.js

var express = require('express');
var app = express();
var server = require('http').createServer(app);
var io = require('socket.io')(server);
var port = process.env.PORT || 8080;
 
server.listen(port, function () {
  console.log('Server listening at port %d', port);
});
 
app.use(express.static(__dirname + '/public'));
 
io.on('connection', function (socket) {
  socket.on('say', function (data) {
    //socket.emit('message', data); // send to all
    socket.broadcast.emit('message', data); // send to all other
  });
});

client.html

<html>
  <head></head>
  <body>
    <script src="/socket.io/socket.io.js"></script>
    <script>
      var socket = io();
      socket.emit('say', 'Hello from: ' + prompt("Your Name?"));
      socket.on('message', function (data) {
        console.log(data);
      });      
    </script>
  </body>
</html>