How To Use Multithreading in Node.js

In Node.js, you can use multithreading to leverage the power of multiple CPU cores and improve the performance of your applications. Starting from Node.js version 12, you can make use of the Worker Threads module to create and manage multithreaded applications. Here's a step-by-step guide on how to use multithreading in Node.js:

Step 1: Install Node.js Ensure that you have Node.js installed on your system. You can download and install the latest stable version from the official Node.js website (https://nodejs.org).

Step 2: Create a new Node.js project Create a new directory for your Node.js project and navigate to it using the command line. Initialize a new Node.js project by running the following command:

csharp
npm init -y        

Step 3: Install dependencies To use the Worker Threads module, you need to install the dependencies. Run the following command to install the dependencies:

npm install worker_threads        

Step 4: Create a worker file Create a new JavaScript file (e.g., worker.js) that will contain the code to be executed in the worker thread. In this file, define the logic that needs to be executed concurrently. For example, let's say you want to calculate the factorial of a large number. You can define a function to perform the calculation:

javascript
// worker.js
function calculateFactorial(number) {
  let result = 1;
  for (let i = 2; i <= number; i++) {
    result *= i;
  }
  return result;
}

// Export the function to be used by the main thread
module.exports = calculateFactorial;        

Step 5: Create the main file Create another JavaScript file (e.g., main.js) that will act as the main thread and spawn the worker threads. In this file, you'll import the Worker class from the worker_threads module and create new worker instances:

javascript
// main.js
const { Worker } = require('worker_threads');

// Create a new worker
const worker = new Worker('./worker.js');

// Pass data to the worker thread
worker.postMessage(10);

// Receive messages from the worker thread
worker.on('message', result => {
  console.log('Factorial:', result);
});

// Handle errors from the worker thread
worker.on('error', error => {
  console.error('Worker error:', error);
});

// Handle the termination of the worker thread
worker.on('exit', code => {
  if (code !== 0)
    console.error('Worker stopped with exit code', code);
});        

Step 6: Run the main file To execute the main file and see the multithreading in action, run the following command in your project directory:

css
node main.js        

The main thread will spawn a worker thread, pass the value 10 to it, and listen for the result. Once the worker thread completes the calculation, it will send the result back to the main thread, which will then log it to the console.

That's it! You have successfully used multithreading in Node.js using the Worker Threads module. You can create multiple worker threads and distribute tasks across them to further parallelize your application and maximize performance.