Thread synchronization with Mutex in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a Mutex in Ruby threading?

A Mutex (short for mutual exclusion) is a tool that allows only one thread to access a shared resource at a time, preventing conflicts and data corruption.

beginner

How do you create a Mutex in Ruby?

You create a Mutex by calling Mutex.new. For example: <br>mutex = Mutex.new

beginner

What does the mutex.synchronize method do?

It locks the mutex before running the code block and unlocks it after the block finishes, ensuring only one thread runs that code at a time.

beginner

Why is thread synchronization important when using shared variables?

Without synchronization, multiple threads can change shared variables at the same time, causing unpredictable results or errors.

intermediate

What happens if you forget to unlock a Mutex?

Other threads waiting for the lock will be blocked forever, causing your program to freeze or deadlock.

What is the main purpose of a Mutex in Ruby threading?

A To prevent multiple threads from accessing shared data at the same time

B To allow multiple threads to run code simultaneously

C To speed up thread execution

D To create new threads automatically

A Mutex ensures that only one thread accesses shared data at a time to avoid conflicts.

Which Ruby method locks and unlocks a Mutex automatically around a block of code?

A mutex.lock

B mutex.synchronize

C mutex.unlock

D mutex.wait

mutex.synchronize locks the mutex before the block and unlocks it after.

What could happen if two threads modify a shared variable without a Mutex?

A The program runs faster

B The variable keeps its original value

C Data corruption or unpredictable results

D Threads automatically synchronize

Without synchronization, simultaneous access can corrupt data or cause errors.

How do you create a new Mutex in Ruby?

A Mutex.new

B Mutex.create

C Thread.new

D Mutex.start

You create a Mutex by calling Mutex.new.

What is a deadlock in the context of Mutex?

A When a thread finishes execution

B When multiple threads run without synchronization

C When a Mutex is unlocked too early

D When threads wait forever because a Mutex is never unlocked

Deadlock happens when threads wait forever because a Mutex is not released.

Explain how a Mutex helps with thread synchronization in Ruby.

Think about how to keep shared data safe when many threads run.

Describe what can go wrong if you do not use a Mutex when multiple threads access shared variables.

Imagine two people writing on the same paper at the same time.