Worker pool pattern in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a new worker thread.

Node.js

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

const worker = new [1]('./worker.js');

Drag options to blanks, or click blank then click option'

AProcess

BThread

CTask

DWorker

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Thread' or 'Process' instead of 'Worker'.

Trying to create a worker without importing the Worker class.

In Node.js, the Worker class from the worker_threads module is used to create a new worker thread.

2fill in blank

medium

Complete the code to send a message from the main thread to the worker.

Node.js

worker.[1]('start');

Drag options to blanks, or click blank then click option'

Asend

BpostMessage

Cemit

Dwrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'send' or 'emit' which are not methods of Worker.

Trying to use 'write' which is for streams.

The postMessage method sends a message to the worker thread.

3fill in blank

hard

Fix the error in the worker code to listen for messages.

Node.js

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

parentPort.[1]('message', (msg) => {
  console.log('Received:', msg);
});

Drag options to blanks, or click blank then click option'

Aon

Bhandle

Clisten

DaddListener

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'listen' or 'handle' which are not valid methods.

Using 'addListener' which works but is less common than 'on'.

The on method is used to listen for events like 'message' on parentPort.

4fill in blank

hard

Fill both blanks to create a pool of 4 workers and store them in an array.

Node.js

const workers = Array.from({ length: 4 }, () => new [1]('./worker.js')); // Create 4 workers

workers.forEach(worker => worker.[2]('ready'));

Drag options to blanks, or click blank then click option'

AWorker

BpostMessage

Csend

DThread

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Thread' instead of 'Worker'.

Using 'send' instead of 'postMessage'.

Use Worker to create new worker threads and postMessage to send messages to them.

5fill in blank

hard

Fill all three blanks to handle worker exit events and restart the worker.

Node.js

workers.forEach((worker, index) => {
  worker.on('exit', (code) => {
    if (code !== 0) {
      console.log(`Worker ${index} exited with code ${code}. Restarting...`);
      workers[[1]] = new [2]('./worker.js');
      workers[[3]].postMessage('start');
    }
  });
});

Drag options to blanks, or click blank then click option'

Aindex

BWorker

DThread

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'Thread' instead of 'Worker'.

Using different variables for the first and third blanks.

Use the index to replace the exited worker, create a new Worker, and send it a 'start' message.