Node 8 - Cluster Express server

express.js

var cluster = require('cluster');

const PORT = 3000;

if (cluster.isMaster) {

    const numWorkers = require('os').cpus().length;

    console.log(`Master cluster setting up ${numWorkers} workers...`);

    workers = [];
    for (let i = 0; i < numWorkers; i++)
        workers[i] = cluster.fork();

    cluster.on('online', worker => {
        console.log(`Worker ${worker.process.pid} is online`);
    });

    cluster.on('exit', (worker, code, signal) => {
        console.log(`Worker ${worker.process.pid} died with code ${code}`);
        console.log('Starting a new worker');
        workers[workers.indexOf(worker)] = cluster.fork();
    });

    /* messages */

    cluster.on('message', (worker, message, handle) => {
        console.log(`message from worker ${worker.process.pid}: ${message.message}`)
    });

    setInterval(() => {

        workers.forEach(worker => {
            worker.send(`hello from master to process ${worker.process.pid}`);
        });

    }, 10000);

} else {

    const app = require('express')();

    app.all('/*', (req, res) => {
        process.send({message: 'hello from worker'});
        res.json({process: process.pid, message: 'Hello'}).end();
    })

    app.listen(PORT, () => {
        console.log(`api on port ${PORT}, pid ${process.pid}`)
    });

    /* messages */

    process.on('message', message => {
        console.log(`message from master: ${message}`);
    });

}