https://blog.appsignal.com/2021/02/03/improving-node-application-performance-with-clustering.html

https://nodejs.org/api/cluster.html

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

if (cluster.isMaster) {
  console.log(`Primary ${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`);
}