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Is CountDownLatch thread-safe?
The CountDownLatch is also thread-safe.
Should CountDownLatch be volatile?
2 Answers. Actually a doesn’t need to be volatile because countDown() loades and stores into volatile state variable of AbstractQueuedSynchronizer which is used inside CountDownLatch . Volatile store triggers a memory-barrier (great in-depth article about Memory Barriers and etc in JSR-133).
What is a CountDownLatch?
CountDownLatch is a concurrency construct that allows one or more threads to wait for a given set of operations to complete. A CountDownLatch is initialized with a given count. This count is decremented by calls to the countDown() method. Calling await() blocks the thread until the count reaches zero.
Is CountDownLatch synchronized?
A CountDownLatch is a versatile synchronization tool and can be used for a number of purposes. A CountDownLatch initialized with a count of one serves as a simple on/off latch, or gate: all threads invoking await wait at the gate until it is opened by a thread invoking countDown() .
Why CountDownLatch is used in Java?
CountDownLatch is used to make sure that a task waits for other threads before it starts. To understand its application, let us consider a server where the main task can only start when all the required services have started.
What happens to the current thread in countdownlatch?
Causes the current thread to wait until the latch has counted down to zero, unless the thread is interrupted , or the specified waiting time elapses. Decrements the count of the latch, releasing all waiting threads if the count reaches zero. Returns the current count. Returns a string identifying this latch, as well as its state.
When to use countdownlatch in Java SE 11?
A CountDownLatch initialized with a count of one serves as a simple on/off latch, or gate: all threads invoking await wait at the gate until it is opened by a thread invoking countDown (). A CountDownLatch initialized to N can be used to make one thread wait until N threads have completed some action, or some action has been completed N times.
How is a countdownlatch initialized to a count?
A CountDownLatch initialized with a count of one serves as a simple on/off latch, or gate: all threads invoking await wait at the gate until it is opened by a thread invoking countDown (). A CountDownLatch initialized to N can be used to make one thread wait until N threads have completed some action, or some action has been completed N times.
Which is a useful property of a countdownlatch?
A useful property of a CountDownLatch is that it doesn’t require that threads calling countDown wait for the count to reach zero before proceeding, it simply prevents any thread from proceeding past an await until all threads could pass. Sample usage: Here is a pair of classes in which a group of worker threads use two countdown latches: