May 11

Visibility problem in Java Multithreading

Multithreading is like juggling—exciting and fast-paced, but it comes with its own set of challenges. One of the trickiest hurdles to overcome is the visibility problem. In this blog, we'll break down what it means, why it matters, and most importantly, how to tackle it head-on.

Understanding the Visibility Problem:

Picture this: you've got multiple threads running simultaneously, each doing its own thing. Now, imagine they all need access to the same piece of data. The visibility problem kicks in when changes made by one thread aren't immediately seen by the others. It's like trying to communicate in a noisy room—things can get lost in translation, leading to confusion and chaos.

Implications of the Visibility Problem:

So, what's the big deal? Well, imagine if one thread updates a shared variable, but another thread still sees the old value. It's a recipe for disaster! Inconsistent data can wreak havoc on your program, causing errors, crashes, and headaches all around. And to make matters worse, modern hardware and compiler optimizations can make the problem even sneakier, hiding inconsistencies behind the scenes.

You can solve Visibility problem by using Volatile keyword (it's one of the ways)

Volatile
Keyword:

This keyword tells the compiler to pay extra attention to a variable, ensuring changes are visible to all threads. It's like waving a flag to get everyone's attention—simple yet effective. 

When
to Use volatile:

  • Use volatile when a variable is accessed by multiple threads without synchronization, and you need to ensure visibility of changes to that variable across threads.

  • Use it for simple flags or status indicators that are frequently read and modified by multiple threads, such as a stop flag in a thread.


Limitations of volatile:

  • volatile only ensures visibility; it does not provide atomicity for compound operations. For atomic operations, you'll need to use other synchronization mechanisms like locks or atomic variables.

  • It's not suitable for scenarios where multiple operations need to be performed atomically on a shared variable.

    Happy Coding!
Created with