Chapter 5. Running Tasks Divided into Phases – The Phaser Class

The most important element in a concurrent API is the synchronization mechanisms it offers to the programmer. Synchronization is the coordination of two or more tasks to get the desired result. You can synchronize the execution of two or more tasks, when they have to be executed in a predefined order, or synchronize the access to a shared resource, when only one thread at a time can execute a fragment of code or modify a block of memory. Java 8 concurrency API provides a lot of synchronization mechanisms from the basic synchronized keyword or the Lock interface and their implementations to protect a critical section to the more advanced CyclicBarrier or CountDownLatch classes that allows you to synchronize the order of execution of different tasks. In Java 7, the concurrency API introduces the Phaser class. This class provides a powerful mechanism (phaser) to execute tasks divided into phases. The task can...