Process forking for parallelism in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does fork do in Ruby?

It creates a new child process that runs in parallel with the parent process. The child is a copy of the parent but runs independently.

beginner

How can you tell if you are in the child or parent process after a fork?

The fork method returns nil in the child process and the child's process ID (PID) in the parent process.

intermediate

Why use Process.wait after forking?

It makes the parent process wait for the child process to finish, ensuring the child completes before the parent continues or exits.

beginner

What is a simple example of using fork to run two tasks in parallel?

You can fork to create a child process that runs one task, while the parent runs another. Both run at the same time.

intermediate

What happens if you don't handle the child process after a fork?

The child process may become a 'zombie' process, which wastes system resources until the parent collects its exit status.

What does the fork method return in the parent process?

A nil

B The child's process ID (PID)

C 0

D An error

In the parent process, fork returns the child's PID, allowing the parent to track the child.

Which method should you use to wait for a child process to finish?

A sleep

B fork

C exit

D Process.wait

Process.wait pauses the parent until the child process ends.

What is the main benefit of using fork in Ruby?

A To run code in parallel using separate processes

B To create threads

C To handle exceptions

D To read files faster

fork creates a new process so tasks can run at the same time.

What value does fork return in the child process?

A 1

B child's PID

C nil

D parent's PID

In the child process, fork returns nil.

What problem occurs if the parent does not wait for the child process?

A Zombie processes may accumulate

B The child process runs twice

C The parent crashes immediately

D The child process never starts

Without waiting, child processes can become zombies, using system resources unnecessarily.

Explain how fork helps run tasks in parallel in Ruby.

Think about how two people can work on different parts of a project at the same time.

Describe why it is important to use Process.wait after forking.

Imagine waiting for your friend to finish before leaving a party together.