Worker thread vs child process in Node.js - Quick Revision & Key Differences

Recall & Review

beginner

What is a Worker Thread in Node.js?

A Worker Thread is a way to run JavaScript code in parallel within the same Node.js process. It shares memory with the main thread but runs independently to perform CPU-intensive tasks without blocking the main event loop.

beginner

What is a Child Process in Node.js?

A Child Process is a separate process created by the main Node.js process. It runs independently with its own memory and event loop, allowing you to run external programs or scripts without blocking the main process.

intermediate

How do Worker Threads and Child Processes differ in memory usage?

Worker Threads share memory with the main thread using SharedArrayBuffer, which allows faster communication. Child Processes have separate memory spaces, so communication happens via inter-process messaging, which is slower.

intermediate

When should you use a Worker Thread instead of a Child Process?

Use Worker Threads for CPU-heavy JavaScript tasks that need to run in parallel but share data efficiently. They are lighter and faster for tasks within Node.js. Use Child Processes when you need to run external programs or isolate tasks completely.

advanced

What is a key limitation of Worker Threads compared to Child Processes?

Worker Threads run in the same process, so if a Worker Thread crashes, it can affect the main process. Child Processes are isolated, so a crash in a child does not crash the main process.

Which Node.js feature runs JavaScript code in parallel within the same process?

A Event Loop

B Child Process

C Worker Thread

D Callback Function

Worker Threads run JavaScript code in parallel inside the same Node.js process.

Which runs in a separate memory space and process?

A Worker Thread

B Child Process

C Promise

D Async Function

Child Processes run in separate processes with their own memory.

Which is better for running external programs from Node.js?

A Child Process

B setTimeout

C Worker Thread

D Event Loop

Child Processes are designed to run external programs or scripts.

Which communicates faster due to shared memory?

A Worker Thread

B File System

C HTTP Request

D Child Process

Worker Threads share memory, enabling faster communication.

What happens if a Worker Thread crashes?

A Only the Worker Thread stops, main process continues

B Nothing happens

C Child Process restarts automatically

D Main process crashes too

Since Worker Threads share the same process, a crash can affect the main process.

Explain the main differences between Worker Threads and Child Processes in Node.js.

Think about memory, process isolation, and use cases.

When would you choose a Child Process over a Worker Thread in a Node.js application?

Consider isolation and running non-JS code.