23.3. Visibility Problems in Multithreading

Try these first

1. 1.

   What does the term 'visibility' refer to in multithreading?

   Hint

   Think about how threads share information.

2. 2.

   What happens if a variable is changed by one thread without synchronization?

   Hint

   Consider what happens when threads read outdated values.

3. 3.

   What is a visibility problem in multithreading?

   • One thread can access memory of another thread
   • A thread does not see an updated variable
   • Two threads execute in the opposite order

   Hint

   Think about how threads view shared data.

4. 4.

   True or False: The volatile keyword guarantees atomicity of variable updates.

   • True
   • False

   Hint

   Consider what atomic actions imply.

5. 5.

   Design a multithreaded Java program with a visibility problem, and then modify it to use volatile to solve the issue.

   Hint

   Make sure you test the initial implementation to observe the issue before applying `volatile`.

6. 6.

   Given a scenario with multiple threads updating and reading a resource, detail a plan to implement proper synchronization to avoid visibility issues.

   Hint

   Consider the crucial operations that must be atomic and visible.