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What are Worker Threads in Node.js and when would you use them?

Q: What are Worker Threads in Node.js and when would you use them?

**TL;DR.** worker_threads run JavaScript on **additional threads within the same process**, each with its own V8 instance and event loop. Use them for **CPU-bound** work (parsing, hashing, image processing) that would otherwise block the main event loop. They can **share memory** via SharedArrayBuffer and communicate by **messages**. one Node process main thread event loop <rect class='d-box' x='212' y='60' width='100' height='70' rx=

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This question explores understanding of Node.js's approach to CPU-bound tasks and parallelism.

worker threadsconcurrencyperformancecpu-bound

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Offload a CPU task to a worker

// main.js
import { Worker } from 'node:worker_threads';
const w = new Worker('./hash-worker.js', { workerData: bigInput });
w.on('message', (digest) => console.log('hash:', digest));

// hash-worker.js
import { parentPort, workerData } from 'node:worker_threads';
import crypto from 'node:crypto';
const digest = crypto.createHash('sha256').update(workerData).digest('hex');
parentPort.postMessage(digest);   // runs off the main thread

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