http.js

'use strict'

const http = require('http')

http.createServer((req, res) => {
  res.end()
}).listen(8000, (err) => {
  if (err) throw err
})

http_cluster.js

'use strict'
const cluster = require('cluster')
const http = require('http')
const cpus = require('os').cpus().length

if (cluster.isMaster) {
  for (var i = 0; i < cpus; i++) {
    cluster.fork()
  }

  cluster.on('exit', function(w, c, s) {
    console.log(`exit ${w.process.pid} died`)
  })
} else {
  http.createServer((req, res) => {
    res.end()
  }).listen(8000, (err) => {
    if (err) throw err
  })
}