[Solved] You want to implement a Node.js cluster that balances load across all CPU cores and automatically restarts workers if they crash. Which code snippet correctly achieves this? | Node.js

Node.js - Cluster Module

You want to implement a Node.js cluster that balances load across all CPU cores and automatically restarts workers if they crash. Which code snippet correctly achieves this?

Aif (cluster.isMaster) { cluster.fork(); cluster.on('exit', () => { console.log('Worker died'); }); } else { require('http').createServer((req, res) => { res.end('Hello'); }).listen(3000); }

Bif (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } cluster.on('exit', (worker) => { console.log(`Worker ${worker.process.pid} died, restarting...`); cluster.fork(); }); } else { require('http').createServer((req, res) => { res.end(`Handled by worker ${process.pid}`); }).listen(3000); }

Cif (cluster.isWorker) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } } else { require('http').createServer((req, res) => { res.end('Worker running'); }).listen(3000); }

Dif (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } } else { require('http').createServer((req, res) => { res.end('Worker running'); }).listen(3000); cluster.on('exit', () => { cluster.fork(); }); }

Step-by-Step Solution

Solution:

Step 1: Fork workers equal to CPU cores in master
if (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } cluster.on('exit', (worker) => { console.log(`Worker ${worker.process.pid} died, restarting...`); cluster.fork(); }); } else { require('http').createServer((req, res) => { res.end(`Handled by worker ${process.pid}`); }).listen(3000); } correctly uses os.cpus().length to fork that many workers in the master process.
Step 2: Restart workers on exit event in master
if (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } cluster.on('exit', (worker) => { console.log(`Worker ${worker.process.pid} died, restarting...`); cluster.fork(); }); } else { require('http').createServer((req, res) => { res.end(`Handled by worker ${process.pid}`); }).listen(3000); } listens to the 'exit' event on cluster and forks a new worker to replace the dead one.
Step 3: Worker creates HTTP server listening on port 3000
if (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } cluster.on('exit', (worker) => { console.log(`Worker ${worker.process.pid} died, restarting...`); cluster.fork(); }); } else { require('http').createServer((req, res) => { res.end(`Handled by worker ${process.pid}`); }).listen(3000); }'s else block creates the server in workers, which is correct for load balancing.
Final Answer:
Forks workers across all CPU cores and automatically restarts workers if they crash -> Option B
Quick Check:
Fork all CPUs + restart on exit = if (cluster.isMaster) { const cpuCount = require('os').cpus().length; for (let i = 0; i < cpuCount; i++) { cluster.fork(); } cluster.on('exit', (worker) => { console.log(`Worker ${worker.process.pid} died, restarting...`); cluster.fork(); }); } else { require('http').createServer((req, res) => { res.end(`Handled by worker ${process.pid}`); }).listen(3000); } [OK]

Quick Trick: Fork all CPUs in master and restart on exit event [OK]

Common Mistakes:

Not forking all CPU cores
Not restarting workers after crash
Forking workers inside worker process
Attaching exit listener inside worker instead of master

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More Node.js Quizzes

You want to implement a Node.js cluster that balances load across all CPU cores and automatically restarts workers if they crash. Which code snippet correctly achieves this?

Step 1: Fork workers equal to CPU cores in master

Step 2: Restart workers on exit event in master

Step 3: Worker creates HTTP server listening on port 3000

Final Answer:

Quick Check:

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