a simple load tester for websocket server which connects a desired number of clients, sends "client _RANDOM_UNIQUE_ID_" and then in a given interval "ping _RANDOM_NUMBER_" prints out any messages sent by the server

websocket_loadtester.js

#!/usr/bin/env node
// to run install: nodejs and the module "websocket"
// npm install websocket
// then execute
// node tester.js _NUMBER_OF_CLIENTS_

var WebSocketClient = require('websocket').client;

var HOST = 'ws://localhost:8449/ws/endpoint';
var PING_TIME_MS = 20000;
var DELAY_BETWEEN_TESTERS_MS=100;

var append = new Date().getTime().toString();
var PREFIX = append.substring(append.length-8, append.length-1);
var counter = 0;

function Tester() {
  this.client = new WebSocketClient();
	
	var clientName = "client_" + PREFIX + "_" + (counter++);
	
	this.client.on('connectFailed', function(error) {
		console.log('Connect Error: ' + error.toString());
	});
	
	this.client.on('connect', function(connection) {
		connection.sendUTF("client " + clientName);
		console.log('WebSocket client connected');
		connection.on('error', function(error) {
			console.log("Connection Error: " + error.toString());
		});
		connection.on('close', function() {
			console.log('echo-protocol Connection Closed');
		});
		connection.on('message', function(message) {
			if (message.type === 'utf8') {
				console.log(new Date().getTime().toString() + " - Received: '" + message.utf8Data + "'");
			}
		});
		
		function sendNumber(connection) {
			if (connection.connected) {
				var number = Math.round(Math.random() * 0xFFFFFF);
				connection.sendUTF("ping " + number.toString());
				setTimeout(function(_this) {sendNumber(_this)}, PING_TIME_MS, connection);
			}
		}
		sendNumber(connection);
	});
	
}

Tester.prototype.go = function() {
	this.client.connect(HOST);
};

var args = process.argv.splice(2);
var testerCount = args.length > 0 ? args[0] : 100;

for (var i=0; i<testerCount; i++) {
	setTimeout(function() {
		new Tester().go();
	}, i*DELAY_BETWEEN_TESTERS_MS);
}