Receiving results from workers in Node.js - Mini Project: Build & Apply

Receiving Results from Workers in Node.js

📖 Scenario: You are building a Node.js application that uses worker threads to perform tasks in the background. You want to receive results from these workers and handle them in the main thread.

🎯 Goal: Create a simple Node.js program that starts a worker thread, sends a task to it, and receives the result back in the main thread.

📋 What You'll Learn

Create a worker thread using the worker_threads module

Send a message from the main thread to the worker

Receive a message from the worker in the main thread

Log the received result in the main thread

💡 Why This Matters

🌍 Real World

Worker threads help Node.js applications perform CPU-heavy tasks without blocking the main thread, improving responsiveness.

💼 Career

Understanding worker threads is important for backend developers building scalable and efficient Node.js applications that handle concurrent tasks.

1

Set up the worker thread file

Create a file named worker.js that imports parentPort from worker_threads and listens for messages using parentPort.on('message', ...).

Node.js

// Your code here to import parentPort and listen for messages

Need a hint?

Use require('worker_threads') to get parentPort. Then use parentPort.on('message', callback) to listen for messages.

2

Add a task handler in the worker

Inside the parentPort.on('message', ...) callback in worker.js, create a variable result that doubles the received value. Then send the result back to the main thread using parentPort.postMessage(result).

Node.js

const { parentPort } = require('worker_threads');

parentPort.on('message', (value) => {
    // Calculate result and send it back
});

Need a hint?

Multiply value by 2 and send it back with parentPort.postMessage().

3

Create the main thread file and start the worker

Create a file named main.js. Import Worker from worker_threads. Create a new Worker instance with the filename './worker.js'. Send the number 10 to the worker using worker.postMessage(10).

Node.js

// Your code here to import Worker and create a worker instance
// Then send 10 to the worker

Need a hint?

Use new Worker('./worker.js') to start the worker and worker.postMessage(10) to send data.

4

Receive and log the result from the worker

In main.js, add a listener for worker.on('message', ...) that receives the result from the worker and logs it using console.log with the text "Result from worker:" followed by the result.

Node.js

const { Worker } = require('worker_threads');

const worker = new Worker('./worker.js');
worker.postMessage(10);

// Add listener to receive message from worker

Need a hint?

Use worker.on('message', callback) to get the result and console.log to show it.