Skip to main content

What is clustering in Node.js and why is it used?

Clustering in Node.js is a technique used to create multiple instances of a Node.js application that can run on different CPU cores. This is important because Node.js runs in a single thread by default, meaning it can only utilize one CPU core—even on multi-core systems.

What is clustering in Node.js and why is it used?

🔧 Why Clustering Is Used

  1. To improve performance and scalability on multi-core machines.

  2. To handle more concurrent requests by distributing load.

  3. To provide basic fault tolerance—if one worker crashes, others continue running.

  4. To avoid blocking the event loop with heavy traffic.

🧠 How It Works

  • Uses the built-in cluster module.

  • The master process spawns worker processes (child processes).

  • Each worker runs its own event loop and can handle requests independently.

  • Workers can share server ports (e.g., http.createServer) via the master process.

🧪 Example

const cluster = require('cluster');
const http = require('http');
const os = require('os');

if (cluster.isMaster) {
  const numCPUs = os.cpus().length;
  console.log(`Master process PID: ${process.pid}`);
  
  // Fork workers
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }

  // Optional: listen for dying workers
  cluster.on('exit', (worker, code, signal) => {
    console.log(`Worker ${worker.process.pid} died, starting a new one`);
    cluster.fork();
  });

} else {
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end(`Handled by worker: ${process.pid}\n`);
  }).listen(3000);

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

⚠️ Notes

Popular posts from this blog

What are the different types of directives in Angular? Give real-world examples.

In Angular, directives are classes that allow you to manipulate the DOM or component behavior . There are three main types of directives: 🧱 1. Component Directives Technically, components are directives with a template. They control a section of the screen (UI) and encapsulate logi c. ✅ Example: @Component ({ selector : 'app-user-card' , template : `<h2>{{ name }}</h2>` }) export class UserCardComponent { name = 'Alice' ; } 📌 Real-World Use: A ProductCardComponent showing product details on an e-commerce site. A ChatMessageComponent displaying individual messages in a chat app. ⚙️ 2. Structural Directives These change the DOM layout by adding or removing elements. ✅ Built-in Examples: *ngIf : Conditionally includes a template. *ngFor : Iterates over a list and renders template for each item. *ngSwitch : Switches views based on a condition. 📌 Real-World Use: < div * ngIf = "user.isLoggedIn...
Read more

Explain the Angular compilation process: View Engine vs. Ivy.

 The Angular compilation process transforms your Angular templates and components into efficient JavaScript code that the browser can execute. Over time, Angular has evolved from the View Engine compiler to a newer, more efficient system called Ivy . Here's a breakdown of the differences between View Engine and Ivy , and how each affects the compilation process: 🔧 1. What Is Angular Compilation? Angular templates ( HTML inside components) are not regular HTML—they include Angular-specific syntax like *ngIf , {{ }} interpolation, and custom directives. The compiler translates these templates into JavaScript instructions that render and update the DOM. Angular uses Ahead-of-Time (AOT) or Just-in-Time (JIT) compilation modes: JIT : Compiles in the browser at runtime (used in development). AOT : Compiles at build time into efficient JS (used in production). 🧱 2. View Engine (Legacy Compiler) ➤ Used in Angular versions < 9 🔍 How It Works: Compiles templat...
Read more

What is Zone.js, and why does Angular rely on it?

Zone.js is a library that Angular relies on to manage asynchronous operations and automatically trigger change detection when necessary. Think of it as a wrapper around JavaScript’s async APIs (like setTimeout , Promise , addEventListener , etc.) that helps Angular know when your app's state might have changed. 🔍 What is Zone.js? Zone.js creates an execution context called a "Zone" that persists across async tasks. It tracks when tasks are scheduled and completed—something JavaScript doesn't do natively. Without Zone.js, Angular wouldn’t automatically know when user interactions or async events (like an HTTP response) occur. You’d have to manually tell Angular to update the UI. ⚙️ Why Angular Uses Zone.js ✅ 1. Automatic Change Detection Zone.js lets Angular detect when an async task finishes and automatically run change detection to update the UI accordingly. Example: ts setTimeout ( () => { this . value = 'Updated!' ; // Angular know...
Read more