How cluster module works in Node.js - Quick Revision & Summary

Recall & Review

beginner

What is the purpose of the Node.js cluster module?

The cluster module allows Node.js to create child processes (workers) that share the same server port, enabling better use of multi-core CPUs and improving performance by handling multiple requests in parallel.

intermediate

How does the cluster module share server ports among worker processes?

Worker processes listen on the same port, and the operating system distributes incoming connections to workers using round-robin load balancing (on some platforms), allowing load balancing across CPU cores without conflicts.

intermediate

What is the role of the master process in the cluster module?

The master process manages worker processes: it creates them, listens for their exit events, and can restart workers if they crash, ensuring the application stays available.

advanced

How do worker processes communicate with the master process in the cluster module?

Workers and the master communicate using an IPC (Inter-Process Communication) channel, allowing them to send messages and coordinate tasks like graceful shutdowns or sharing state.

intermediate

What happens if a worker process crashes in a Node.js cluster setup?

The master process detects the crash via an 'exit' event and can automatically spawn a new worker to replace the crashed one, keeping the service running smoothly.

What does the Node.js cluster module primarily help with?

A Creating user interfaces

B Improving database queries

C Managing file uploads

D Utilizing multiple CPU cores to handle requests

The cluster module helps Node.js apps use multiple CPU cores by creating worker processes.

Who creates the worker processes in a Node.js cluster?

A The master process

B Each worker creates itself

C The operating system automatically

D The client browser

The master process is responsible for creating and managing worker processes.

How do workers share the same port in a cluster?

A Workers do not share ports

B The operating system distributes connections to workers

C Each worker listens on a different port

D Workers use different IP addresses

Workers listen on the shared port, and the operating system distributes incoming connections to workers.

What happens when a worker crashes in a cluster?

A The master restarts a new worker

B The whole server stops

C Nothing happens automatically

D The client reconnects automatically

The master detects the crash and can restart a new worker to maintain service.

Which communication method is used between master and workers?

A HTTP requests

B WebSockets

C IPC (Inter-Process Communication)

D File system polling

Master and workers communicate via IPC channels built into Node.js cluster.

Explain how the Node.js cluster module improves application performance on multi-core systems.

Think about how multiple workers handle requests at the same time.

Describe the lifecycle of a worker process in the Node.js cluster module.

Consider what happens from start to crash and restart.