java CyclicBarrier-优快云博客

本文深入解析了CyclicBarrier的工作原理及使用场景，对比CountDownLatch，介绍了CyclicBarrier的可复用特性，通过示例代码展示了如何让一组固定大小的线程在达到共同屏障点后继续执行。

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CyclicBarrier   api的描述如下，
* A synchronization aid that allows a set of threads to all wait for
* each other to reach a common barrier point.  CyclicBarriers are
* useful in programs involving a fixed sized party of threads that
* must occasionally wait for each other. The barrier is called
* <em>cyclic</em> because it can be re-used after the waiting threads
* are released.

CyclicBarrier是所有的线程都必须相互等待，达到公共的屏障点，在释放屏障点后是可以重复使用的，这一点比

CountDownLatch好一些

CyclicBarrier包含的方法如下：

package com.ls.skynet;

import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CyclicBarrier;

public class CyclicBarrierTest {
    public static void main(String[] args) {
        //朋友约好一起出发去旅行
        final CyclicBarrier cyclicBarrier = new CyclicBarrier(3);
        for(int i=0;i<3;i++){
            Thread t = new Thread(new TravelThread(cyclicBarrier));
            t.start();

                System.out.println("有多少个wait parties"+cyclicBarrier.getNumberWaiting());


        }
        cyclicBarrier.reset();
        System.out.println(cyclicBarrier.getNumberWaiting());
        System.out.println(cyclicBarrier.getParties());
    }

    public static class TravelThread implements Runnable{
         final CyclicBarrier cyc ;
         TravelThread(CyclicBarrier cyc ){
            this.cyc = cyc;
        }
        public void run(){
            try {
                cyc.await();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (BrokenBarrierException e) {
                e.printStackTrace();
            }
        }
    }
}