Why clustering matters for performance in Node.js - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a cluster using Node.js cluster module.

Node.js

const cluster = require('cluster');
if (cluster.isMaster) {
  console.log('Master process is running');
  cluster.fork();
} else {
  console.log('Worker process [1]');
}

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

Aforked

Bstarted

Crunning

Dcreated

Attempts:

3 left

💡 Hint

Common Mistakes

Using past tense like 'started' or 'created' which is less common here.

The worker process logs 'running' to indicate it is active.

2fill in blank

medium

Complete the code to get the number of CPU cores for clustering.

Node.js

const os = require('os');
const numCPUs = os.[1]().length;
console.log(`Number of CPUs: ${numCPUs}`);

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

Acpus

BcpuCount

CcpuCores

DnumCpus

Attempts:

3 left

💡 Hint

Common Mistakes

Using non-existent methods like 'cpuCount' or 'numCpus'.

The correct method to get CPU info is os.cpus().

3fill in blank

hard

Fix the error in the code to properly fork workers for each CPU core.

Node.js

const cluster = require('cluster');
const os = require('os');
if (cluster.isMaster) {
  const cpuCount = os.cpus().length;
  for (let i = 0; i < [1]; i++) {
    cluster.fork();
  }
}

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

Aos.cpus().length

BcpuCount

Ccluster.cpus

DcpuCount.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using os.cpus().length directly in the loop condition causes repeated calls.

The variable cpuCount holds the number of CPUs and should be used in the loop.

4fill in blank

hard

Fill both blanks to handle worker exit and restart a new worker.

Node.js

cluster.on('exit', (worker, code, signal) => {
  console.log(`Worker [1] died`);
  cluster.[2]();
});

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

Aprocess

Bfork

Crestart

Dexit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'restart' which is not a cluster method.

When a worker process dies, log 'process' and fork a new worker.

5fill in blank

hard

Fill all three blanks to create a simple HTTP server in each worker.

Node.js

const http = require('http');
if (cluster.isWorker) {
  http.createServer((req, res) => {
    res.writeHead([1], {'Content-Type': [2]);
    res.end([3]);
  }).listen(8000);
}

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

A200

B'text/plain'

C'Hello from worker!'

D'application/json'

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong status codes or content types like 'application/json'.

The server responds with status 200, content type text/plain, and a simple text message.