var cluster = require('cluster');
var os = require('os');
//获取CPU数量
var numCPUs=os.cpus().length;
var workers = {};
if(cluster.isMaster) {
  //主进程分支
  cluster.on('death', function (worker) {
     //当一个工作进程结束时，重启工作进程
    delete workers[worker.pid];
    worker = cluster.fork();
    workers[worker.pid] = worker;
  });
  //初始开启与CPU数量相同的工作进程
  for (var i = 0; i < numCPUs; i++) {
    var worker = cluster.fork();
    workers[worker.pid] = worker;
  }
}
else {
  //工作进程分支，启动服务器
  var app = require('./app');
  app.listen(8080);
  console.log("Express服务器启动, 开始监听8080端口, 以 %s 模式运行.", app.settings.env);
}
//当主进程被终止时，关闭所有工作进程
process.on('SIGTERM', function () {
  for (var pid in workers) {
    process.kill(pid);
  }
  process.exit(0);
});