cluster.example.js

var cluster = require('cluster')
var http = require('http')
var numCPUs = require('os').cpus().length

if (cluster.isMaster) {
  console.log('[master] ' + 'start master...')

  for (var i = 0; i < numCPUs; i++) {
    var wk = cluster.fork()
    wk.send('[master] ' + 'hi worker' + wk.id)
  }

  cluster.on('fork', (worker) => {
    console.log('[master] ' + 'fork: worker' + worker.id)
  })

  cluster.on('online', (worker) => {
    console.log('[master] ' + 'online: worker' + worker.id)
  })

  cluster.on('listening', (worker, address) => {
    console.log('[master] ' + 'listening: worker' + worker.id + ',pid:' + worker.process.pid + ', Address:' + address.address + ':' + address.port)
  })

  cluster.on('disconnect', (worker) => {
    console.log('[master] ' + 'disconnect: worker' + worker.id)
  })

  cluster.on('exit', (worker, code, signal) => {
    console.log('[master] ' + 'exit worker' + worker.id + ' died')
  })

  function eachWorker (callback) {
    for (var id in cluster.workers) {
      callback(cluster.workers[id])
    }
  }

  setTimeout(() => {
    eachWorker((worker) => {
      worker.send('[master] ' + 'send message to worker' + worker.id)
    })
  }, 3000)

  Object.keys(cluster.workers).forEach((id) => {
    cluster.workers[id].on('message', (msg) => {
      console.log('[master] ' + 'message ' + msg)
    })
  })
} else if (cluster.isWorker) {
  console.log('[worker] ' + 'start worker ...' + cluster.worker.id)

  process.on('message', (msg) => {
    console.log('[worker] ' + msg)
    process.send('[worker] worker' + cluster.worker.id + ' received!')
  })

  http.createServer((req, res) => {
    res.writeHead(200, {'content-type': 'text/html'})
    res.end('worker' + cluster.worker.id + ',PID:' + process.pid)
  }).listen(3000)
}

// test curl localhost:3000