集群示例

Node.js 的单个实例在单个线程中运行。为了利用多核系统，可以在 Node.js 进程集群中启动应用程序来处理负载。

cluster 模块允许你轻松创建所有共享服务器端口的子进程。

下面的示例在主进程中创建 worker 子进程，以处理跨多个核的负载。

例

const cluster = require('cluster');
const http = require('http');
const numCPUs = require('os').cpus().length; //number of CPUS

if (cluster.isMaster) {
  // Fork workers.
  for (var i = 0; i < numCPUs; i++) {
    cluster.fork();    //creating child process
  }

  //on exit of cluster
  cluster.on('exit', (worker, code, signal) => {
      if (signal) {
        console.log(`worker was killed by signal: ${signal}`);
      } else if (code !== 0) {
        console.log(`worker exited with error code: ${code}`);
      } else {
        console.log('worker success!');
      }
  });
} else {
  // Workers can share any TCP connection
  // In this case it is an HTTP server
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end('hello world\n');
  }).listen(3000);
}