Nodejs cluster module usage

What is clustering?!

When building a production application, you are usually on the lookout for ways to optimize its performance while keeping any possible trade-offs in mind. we'll take a look at an approach that can give you a quick win when it comes to improving the way your Node.js apps handle the workload.

An instance of Node.js runs in a single thread which means that on a multi-core system (which most computers are these days), not all cores will be utilized by the app. To take advantage of the other available cores, you can launch a cluster of Node.js processes and distribute the load between them.

Having multiple threads to handle requests improves the throughput (requests/second) of your server as several clients can be served concurrently. We'll see how to create child processes with the Node.js cluster module and then later, we'll take a look at how to manage clustering with the PM2 Process Manager.

Routine is fully compatible with Nodejs cluster module

Below is a minimal viable example to work with in cluster module

const Routine = require('routinejs')
const cluster = require('cluster')
const totalCPUs = require('os').cpus().length

if (cluster.isMaster) {
    console.log(`Number of CPUs is ${totalCPUs}`)
    console.log(`Master ${process.pid} is running`)

    // Fork workers.
    for (let i = 0; i < totalCPUs; i++) {
        cluster.fork()
    }

    cluster.on('exit', (worker, code, signal) => {
        console.log(`worker ${worker.process.pid} died`)
        console.log("Let's fork another worker!")
        cluster.fork()
    })
} else {
    const app = new Routine({
        enableBodyParsing: true,
        catchErrors: true,
    })

    app.get('/user', (req, res) => {
        res.json('worked :D')
    })

    app.listen(8080)
}