阿里校招在线笔试nodejs题

alibaba_online_test_nodejs.js

/**
 * 实现一个nodejs的Master-Worker的小程序，要求：
 * 1. Master维护与cpu核数相同的Worker的数量；
 * 2. Master接收到Worker的disconnect消息时，重启新的Worker进程；
 * 3. Worker监听1024端口并输出“Hello World”；
 * 4. 在Worker遇到uncaughtException时，通知Master进程并等待3s后退出
 */

var os = require('os'),
  cluster = require('cluster'),
  http = require('http'),
  cpuNum = os.cpus().length;

if (cluster.isMaster) {

  for (var i = 0; i < cpuNum; i++) {
    cluster.fork();
  }

  process.on('message', function(m) {
    console.log('message recv!');
    if (m.msg === 'error') {
      console.log('error occured on worker #' + m.worker.id);
      cluster.fork();
    }
  });

  cluster.on('online', function(worker) {
    console.log('worker #' + worker.id + ' is online on process #' + worker.process.pid);
  });

  cluster.on('disconnect', function(worker) {
    console.log('disconnect worker#', worker.id);
    worker.kill();
    cluster.fork();
  });

} else {

  http.createServer(function(req, res) {
    res.writeHead(200);
    res.end('Hello world!');
  }).listen(2014);

  cluster.worker.on('error', function(code, signal) {
    console.log('error', process.pid, code, signal);
    process.send({
      msg: 'error',
      worker: cluster.worker
    });
    setTimeout(function() {
      cluster.worker.kill();
    }, 3000);
  });
}