Why child processes are needed in Node.js - Challenge Your Understanding

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why use child processes in Node.js?

Why do developers use child processes in Node.js applications?

A To reduce the size of the Node.js application package

B To make the code shorter and easier to read

C To run multiple tasks in parallel without blocking the main event loop

D To automatically fix bugs in the main process

💡 Hint

Think about how Node.js handles tasks and what happens when a task takes a long time.

Node.js runs on a single thread, so long-running tasks can block the main event loop. Child processes allow running tasks in parallel, preventing blocking.

❓ component_behavior

intermediate

Behavior of child processes in Node.js

What happens to the main Node.js process when a child process is running a CPU-intensive task?

A The main process slows down but does not crash

B The main process crashes immediately

C The main process pauses until the child process finishes

D The main process continues running smoothly without being blocked

💡 Hint

Child processes run separately from the main process.

Child processes run independently, so the main process stays responsive even during heavy tasks.

📝 Syntax

advanced

Correct way to create a child process in Node.js

Which code snippet correctly creates a child process to run a separate script?

Node.js

const { fork, spawn, exec } = require('child_process');

A const child = fork('script.js');

B const child = fork('node script.js');

C const child = exec('fork script.js');

D const child = spawn('node script.js');

💡 Hint

fork() runs a Node.js module as a child process.

fork() is used to create a child process running a Node.js module. spawn() and exec() run commands but require different arguments.

🔧 Debug

advanced

Identify the error in child process communication

What error will occur with this code snippet? const { fork } = require('child_process'); const child = fork('child.js'); child.send('Hello'); // But child.js is missing process.on('message') listener

A The message is sent but not received or logged

B Error: process.send is not a function

C No error, message is received and logged

D SyntaxError due to missing listener

💡 Hint

What happens if the child process does not listen for messages?

If the child process does not listen for messages, the message is sent but ignored silently. No error occurs.

❓ lifecycle

expert

Child process lifecycle and exit codes

What is the correct way to detect if a child process exited successfully in Node.js?

A Listen to the 'close' event and check if exit code is 1

B Listen to the 'exit' event and check if exit code is 0

C Use child.kill() and check for errors

D Check if child process object is null

💡 Hint

Exit code 0 means success in most systems.

The 'exit' event provides the exit code. A code of 0 means the child process ended successfully.