Any practical example of LockSupport & AbstractQueuedSynchronizer use?

Question

Guys, can anyone give a simple practical example of LockSupport & AbstractQueuedSynchronizer use? Example given in javadocs is quite strained.<

Answer 1

AFAIK, AbstractQueuedSynchronizer is used to manage state transitions. The JDK uses it to extend Sync, an internal class for java.util.concurrent.FutureTask. The Sync class manages the states (READY, RUNNING, RAN, and CANCELLED) of FutureTask and the transitions between them.

This allows, as you may know, FutureTask to block on FutureTask.get() until the RAN state is reached, for example.