Top Most Counting Semaphore Example in Java 5 – Concurrency Tutorial

Counting Semaphore in Java is a synchronizer which allows to impose a bound on resource is added in Java 5 along with other popular concurrent utilities like CountDownLatch, CyclicBarrier and Exchanger etc. Counting Semaphore in Java maintains specified number of pass or permits, In order to access a shared resource, Current Thread must acquire a permit. If permit is already exhausted by other thread than it can wait until a permit is available due to release of permit from different thread. This concurrency utility can be very useful to implement producer consumer design pattern or implement bounded pool or resources like Thread Pool, DB Connection pool etc. java.util.Semaphore class represent a Counting semaphore which is initialized with number of permits. Semaphore provides two main method acquire() and release() for getting permits and releasing permits. acquire() method blocks until permit is available. Semaphore provides both blocking method as well as unblocking method to acquire permits. This Java concurrency tutorial focus on a very simple example of Binary Semaphore and demonstrate how mutual exclusion can be achieved using Semaphore in Java.

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