Optimizing Node.js Server Performance with Clustering

Introduction

Node.js runs in a single thread by default. This guide demonstrates how to use the cluster module to distribute workload across multiple CPU cores for improved performance.

Prerequisites

• Node.js >=16

Step 1: Create Cluster Entry Point

Create cluster.js:

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

if (cluster.isMaster) {
  console.log(`Master process ${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`);
    cluster.fork(); // restart on failure
  });
} else {
  require("./server"); // worker processes run the server
}

Step 2: Create Server File

Create server.js:

const http = require("http");

const server = http.createServer((req, res) => {
  res.writeHead(200);
  res.end("Hello World");
});

server.listen(3000, () => {
  console.log(`Worker ${process.pid} started server`);
});

Step 3: Run the Cluster

node cluster.js

Step 4: Test Load Distribution

Use ab or autocannon to send requests; observe multiple worker logs.

autocannon -c 100 -d 30 http://localhost:3000

Summary

Clustering allows Node.js to fully utilize multiple CPU cores, improving throughput and resilience by restarting workers on failure.