memo.js

const cluster = require('cluster');
const numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
  for (let i = 0; i < numCPUs; i++) cluster.fork()
  for (const id in cluster.workers) {
    cluster.workers[id].on('message', (data) => {
      console.log(data)
      cluster.workers[id].send({cmd: 'from master'})
    })
  }

  cluster.on('exit', (worker, code, signal) => {
    console.log(`worker ${worker.process.pid} died`);
  })
} else {
  process.on('message', (data) => {
    console.log(data)
  })
  process.send({cmd: 'from forked'});
}