What are Barriers and how they works ?

Barriers

• similar to Latches
• blocks n threads until some event has occurred
• In order to proceed, n must come together at a barrier point at the same time.

How Barriers works ?

• After reaching at barrier point, thread calls await() method.
• await() blocks until all the threads have reached the barrier point.

• When all threads arrives at the barrier point
• Barrier is passed
• All threads are released
• Barrier is reset so it can be used again. 
• await() returns a unique arrival index for each thread
• If a call to await()times out or a thread blocked in await() is interrupted
• Barrier is broken
• All other calls to await() terminate with BrokenBarrierException.