What is the principle behind the cyclic barrier?

CyclicBarrier is a synchronization utility class in Java that allows a group of threads to wait for each other to reach a common point. It can be used to address issues related to multi-threaded collaboration, operating on the principle as follows:

1. The CyclicBarrier consists of a counter, a blocking queue, and a barrier point for resetting the counter.
2. When a thread calls the await() method of a CyclicBarrier, it will be blocked until the counter reaches the specified threshold value.
3. When the value of the counter reaches the threshold, all blocked threads will be released, and the counter will be reset to its initial value.
4. The CyclicBarrier can be reused multiple times once the counter is reset.
5. If a thread is interrupted or times out while waiting, the CyclicBarrier will throw a BrokenBarrierException to indicate that the barrier has been broken.

The principle of CyclicBarrier is to use a counter and a blocking queue to achieve synchronization and waiting between multiple threads. It can be used to solve scenarios where all threads need to reach a certain point before continuing, such as multiple threads simultaneously executing different subtasks, waiting for all subtasks to complete before continuing with the main task.