Why/How to create a nodejs cluster?

Clustering in Node.js refers to the ability to create a group of child processes that can share server ports and work together to handle incoming requests. Clustering is a way to improve the performance and scalability of a Node.js application, by taking advantage of multiple CPU cores and distributing the workload across multiple processes.

To create a cluster in Node.js, you can use the cluster module, which is part of the Node.js core. The cluster module allows you to create a master process that can spawn and manage a group of worker processes. Each worker process runs a separate instance of the application, and the master process distributes incoming requests to the workers using a round-robin algorithm.

Here is an example of how to create a cluster in Node.js:

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

if (cluster.isMaster) {
    console.log(`Master ${process.pid} is running`);

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

    cluster.on('exit', (worker, code, signal) => {
        console.log(`worker ${worker.process.pid} died`);
    });
} else {
    // Workers can share any TCP connection
    // In this case it is an HTTP server
    http.createServer((req, res) => {
        res.writeHead(200);
        res.end('hello world\n');
    }).listen(8000);

    console.log(`Worker ${process.pid} started`);
}

In this example, the master process creates a worker process for each CPU core, and each worker process runs an HTTP server that listens on port 8000. When an incoming request is received, the master process distributes it to one of the worker processes using a round-robin algorithm. This allows the application to handle multiple requests concurrently and improve its overall performance and scalability.