CyclicBarrier

CyclicBarrier：多个线程同时工作以完成同一件事情，但在完成过程中，往往会等待其他线程都完成某一阶段后再执行，等所有线程都到达某一个阶段后再统一执行。CyclicBarrier最重要的属性就是参与者个数，另外最要方法是await()。当所有线程都调用了await()后，就表示这些线程都可以继续执行，否则就会等待。

package com.jerry.concurrency; import java.util.concurrent.BrokenBarrierException; import java.util.concurrent.CyclicBarrier; import java.util.concurrent.ExecutorService; import java.util.concurrent.Executors; public class TestCyclicBarrier { public static void main(String[] args) throws Exception{ // 4个年级 final CyclicBarrier barrier = new CyclicBarrier(4); ExecutorService exec = Executors.newFixedThreadPool(4); exec.submit(new Runnable() { @Override public void run() { try { Thread.sleep(5 * 1000);//一年级上5节课后放学 System.out.println("一年级上完5节课了"); barrier.await(); Thread.sleep(6 * 1000);//一年级放学走了 System.out.println("一年级放学走了"); barrier.await(); } catch (InterruptedException e) { e.printStackTrace(); } catch (BrokenBarrierException e) { e.printStackTrace(); } } }); exec.submit(new Runnable() { @Override public void run() { try { Thread.sleep(4 * 1000);//二年级上4节课后放学 System.out.println("二年级上完4节课了"); barrier.await(); Thread.sleep(3 * 1000);//二年级放学走了 System.out.println("二年级放学走了"); barrier.await(); } catch (InterruptedException e) { e.printStackTrace(); } catch (BrokenBarrierException e) { e.printStackTrace(); } } }); exec.submit(new Runnable() { @Override public void run() { try { Thread.sleep(6* 1000);//三年级上5节课后放学 System.out.println("三年级上6节课了"); barrier.await(); Thread.sleep(6 * 1000); System.out.println("三年级放学走了"); barrier.await(); } catch (InterruptedException e) { e.printStackTrace(); } catch (BrokenBarrierException e) { e.printStackTrace(); } } }); exec.submit(new Runnable() { @Override public void run() { try { Thread.sleep(1 * 1000);//四年级上10节课后放学 System.out.println("四年级上完1节课了"); barrier.await(); Thread.sleep(7 * 1000); System.out.println("四年级放学走了"); barrier.await(); } catch (InterruptedException e) { e.printStackTrace(); } catch (BrokenBarrierException e) { e.printStackTrace(); } } }); exec.shutdown(); } }