start server.js in cluster mode

node_modules/throng/lib/throng.js

@@ -0,0 +1,74 @@
+'use strict';
+
+const cluster = require('cluster');
+const EventEmitter = require('events').EventEmitter;
+const defaults = require('lodash.defaults');
+const cpuCount = require('os').cpus().length;
+
+const DEFAULT_OPTIONS = {
+  workers: cpuCount,
+  lifetime: Infinity,
+  grace: 5000
+};
+
+const NOOP = () => {};
+
+module.exports = function throng(options, startFunction) {
+  options = options || {};
+  let startFn = options.start || startFunction || options;
+  let masterFn = options.master || NOOP;
+
+  if (typeof startFn !== 'function') {
+    throw new Error('Start function required');
+  }
+  if (cluster.isWorker) {
+    return startFn(cluster.worker.id);
+  }
+
+  let opts = isNaN(options) ?
+    defaults(options, DEFAULT_OPTIONS) : defaults({ workers: options }, DEFAULT_OPTIONS);
+  let emitter = new EventEmitter();
+  let running = true;
+  let runUntil = Date.now() + opts.lifetime;
+
+  listen();
+  masterFn();
+  fork();
+
+  function listen() {
+    cluster.on('exit', revive);
+    emitter.once('shutdown', shutdown);
+    process
+      .on('SIGINT', proxySignal)
+      .on('SIGTERM', proxySignal);
+  }
+
+  function fork() {
+    for (var i = 0; i < opts.workers; i++) {
+      cluster.fork();
+    }
+  }
+
+  function proxySignal() {
+    emitter.emit('shutdown');
+  }
+
+  function shutdown() {
+    running = false;
+    for (var id in cluster.workers) {
+      cluster.workers[id].process.kill();
+    }
+    setTimeout(forceKill, opts.grace).unref();
+  }
+
+  function revive(worker, code, signal) {
+    if (running && Date.now() < runUntil) cluster.fork();
+  }
+
+  function forceKill() {
+    for (var id in cluster.workers) {
+      cluster.workers[id].kill();
+    }
+    process.exit();
+  }
+};