Passing data to workers in Node.js - Mini Project: Build & Apply

Passing data to workers in Node.js

📖 Scenario: You are building a Node.js application that needs to perform a heavy calculation without blocking the main program. To do this, you will use a worker thread and pass data to it.

🎯 Goal: Create a worker thread in Node.js and pass a number to it. The worker will calculate the square of the number and send the result back.

📋 What You'll Learn

Create a worker thread using the worker_threads module

Pass a number to the worker using workerData

In the worker, calculate the square of the number

Send the result back to the main thread using parentPort.postMessage

Receive the result in the main thread and handle it

💡 Why This Matters

🌍 Real World

Using worker threads helps Node.js applications perform heavy tasks without freezing the user interface or main process.

💼 Career

Understanding how to pass data to workers and handle their responses is important for building efficient, scalable Node.js applications.

1

Set up the main thread with worker import and data

Create a constant called Worker by requiring 'worker_threads' module. Then create a constant called numberToSquare and set it to 7.

Node.js

// Your code here

Need a hint?

Use require('worker_threads') to get the Worker class. Then create a variable numberToSquare with value 7.

2

Create a worker and pass data using workerData

Create a new Worker instance called worker using new Worker. Pass the filename __filename and an options object with workerData set to numberToSquare.

Node.js

const { Worker } = require('worker_threads');
const numberToSquare = 7;

// Create a worker and pass numberToSquare as workerData
// Your code here

Need a hint?

Use new Worker(__filename, { workerData: numberToSquare }) to create the worker and pass the data.

3

Add worker code to calculate square and send result

Check if !isMainThread. If true, import workerData and parentPort from worker_threads. Calculate the square of workerData and send it back using parentPort.postMessage.

Node.js

const { Worker, isMainThread, workerData, parentPort } = require('worker_threads');
const numberToSquare = 7;

const worker = new Worker(__filename, { workerData: numberToSquare });

// If not main thread, calculate square and send result
// Your code here

Need a hint?

Use if (isMainThread) to separate main and worker code. In the worker, calculate square and send it with parentPort.postMessage.

4

Receive the result from worker in main thread

Inside the if (isMainThread) block, add an event listener on worker for 'message'. The listener function should receive result and assign it to a constant called finalResult.

Node.js

const { Worker, isMainThread, workerData, parentPort } = require('worker_threads');
const numberToSquare = 7;

if (isMainThread) {
  const worker = new Worker(__filename, { workerData: numberToSquare });
  // Listen for message from worker and save to finalResult
  // Your code here
} else {
  const result = workerData * workerData;
  parentPort.postMessage(result);
}

Need a hint?

Use worker.on('message', (result) => { ... }) to get the result from the worker and store it in finalResult.