Java Memory Model Explained Part 2 | Volatile, Synchronize, Happens-Before & CPU Cache Effects

In Part 1, we saw a Java program that compiled perfectly but behaved incorrectly at runtime — a worker thread that never stopped, even after a shared flag was updated. In Part 2, we go deep into why that happens. What you’ll learn in this video: How Thread Stacks and the Heap actually work in Java. Why threads can see stale values even when code looks correct. The two most common concurrency bugs: Race conditions Visibility problems How synchronized guarantees atomicity and visibility? When and why to use the volatile keyword? What instruction reordering is — and why it breaks multi-threaded code? The happens-before relationship, explained with real examples. How CPU cache coherency works under the hood? What false sharing is and why it hurts performance in high-throughput systems? This video is ideal for: Backend engineers Interview preparation ▶️ Watch Part 1 first to see the bug that started this entire discussion. #Java #Concurrency #JavaMemoryModel #Multithreading #Volatile #Synchronized #HappensBefore #CPUCache #CacheCoherency #FalseSharing #BackendEngineering #SoftwareArchitecture #PerformanceEngineering