JAVA中的CountDownLatch、CyclicBarrier、Semaphore的简单测试

因公司需要做一个对于CountDownLatch的分享，特写了此blog。

具体细节可以参见：小结java自带的跟锁相关的一些类

 在做这个分享的过程中发现了Main和junit的运行的区别，在另外一个Blog细说。

详见：http://www.cnblogs.com/yangzhilong/p/6840791.html

package com.yzl.dubbo;

import java.util.Random;
import java.util.concurrent.BrokenBarrierException;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.CyclicBarrier;
import java.util.concurrent.Semaphore;

/**
 * 测试CountDownLatch、CyclicBarrier、Semaphore
 * 这里的测试请在Main方法中进行测试，在junit会出现问题，原因是：junit是Daemon线程
 * 
 * @author yangzhilong
 *
 */
public class MyTest {
    
    public static void main(String[] args) {
        MyTest myTest = new MyTest();
        myTest.testCountDownLatch();
//        myTest.testCyclicBarrier1();
//        myTest.testCyclicBarrier2();
//        myTest.testSemaphore();
    }
        
    /**
     * 测试CountDownLatch
     * 
     */
    @org.junit.Test
    public void testCountDownLatch(){
        CountDownLatch latch = new CountDownLatch(5);
        
        Thread[] threads = new Thread[5];
        Thread thread = null;
        
        System.out.println("begin.....................，" + System.currentTimeMillis());
        for (int i = 0; i < 5; i++) {
            final int index = i;
            thread = new Thread(()->{
                
                System.out.println("Thread-" + index + ",准备执行!!!，" + System.currentTimeMillis());
                //计数器减一
                latch.countDown();
                try {
                    //等待计数器变成0
                    latch.await();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread-" + index + ",开始执行!!!，" + System.currentTimeMillis());
                
                try {
                    Thread.sleep(new Random().nextInt(500));
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                } finally {
                    System.out.println("finally index：" + index);
                }
                System.out.println("Thread-" + index + ",执行完成!!!，" + System.currentTimeMillis());
                
            });
            threads[i] = thread;
        }
        for (Thread t : threads) {
            t.setDaemon(false);
            t.start();
        }
        System.out.println("end..............，" + System.currentTimeMillis());
    }
    
    /**
     * 测试CyclicBarrier-1
     */
    @org.junit.Test
    public void testCyclicBarrier1(){
        CyclicBarrier cyclicBarrier = new CyclicBarrier(6);
        
        System.out.println("begin.....................，" + System.currentTimeMillis());
        for (int i = 0; i < 5; i++) {
            final int index = i;
            new Thread(()->{
                System.out.println("Thread-" + index + ",准备执行!!!，" + System.currentTimeMillis());
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException | BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread-" + index + ",开始执行!!!，" + System.currentTimeMillis());
                
                try {
                    Thread.sleep(new Random().nextInt(500));
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                System.out.println("Thread-" + index + ",执行完成!!!，" + System.currentTimeMillis());
            }).start();;
        }

        try {
            cyclicBarrier.await();
        } catch (InterruptedException | BrokenBarrierException e) {
            e.printStackTrace();
        }

        System.out.println("end..............，" + System.currentTimeMillis());
    }
    
    /**
     * 测试CyclicBarrier-2
     * 程序中会重置计数器
     */
    @org.junit.Test
    public void testCyclicBarrier2(){
        CyclicBarrier cyclicBarrier = new CyclicBarrier(6);
        
        System.out.println("begin.....................，" + System.currentTimeMillis());
        for (int i = 0; i < 5; i++) {
            final int index = i;
            new Thread(()->{
                System.out.println("Thread-" + index + ",准备执行!!!，" + System.currentTimeMillis());
                try {
                    cyclicBarrier.await();
                } catch (InterruptedException | BrokenBarrierException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread-" + index + ",开始执行!!!，" + System.currentTimeMillis());
                
                try {
                    Thread.sleep(new Random().nextInt(500));
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                
                System.out.println("Thread-" + index + ",执行完成!!!，" + System.currentTimeMillis());
            }).start();;
        }

        try {
            cyclicBarrier.await();
        } catch (InterruptedException | BrokenBarrierException e) {
            e.printStackTrace();
        }

        System.out.println("end..............，" + System.currentTimeMillis());
        
        //重置计数器
        cyclicBarrier.reset();
        
        try {
            cyclicBarrier.await();
        } catch (InterruptedException | BrokenBarrierException e) {
            e.printStackTrace();
        }
        System.out.println("我永远都不能被执行到");
    }
    
    /**
     * 测试Semaphore
     */
    @org.junit.Test
    public void testSemaphore(){
        Semaphore semaphore = new Semaphore(1);
        
        System.out.println("begin.....................");
        for (int i = 0; i < 5; i++) {
            final int index = i;
            new Thread(()->{
                System.out.println("Thread-" + index + ",准备执行!!!，" + System.currentTimeMillis());
                try {
                    semaphore.acquire();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("Thread-" + index + ",开始执行!!!");
                
                try {
                    Thread.sleep(new Random().nextInt(500));
                } catch (InterruptedException e1) {
                    e1.printStackTrace();
                }
                
                System.out.println("Thread-" + index + ",执行完成!!!");
                semaphore.release();
            }).start();
        }
        System.out.println("end..............");
        try {
            Thread.sleep(100000L);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

运行结果：

begin.....................，1494483205995
end..............，1494483206092
Thread-0,准备执行!!!，1494483206094
Thread-2,准备执行!!!，1494483206094
Thread-3,准备执行!!!，1494483206094
Thread-4,准备执行!!!，1494483206094
Thread-1,准备执行!!!，1494483206094
Thread-1,开始执行!!!，1494483206094
Thread-2,开始执行!!!，1494483206095
Thread-0,开始执行!!!，1494483206095
Thread-3,开始执行!!!，1494483206095
Thread-4,开始执行!!!，1494483206095
finally index：4
Thread-4,执行完成!!!，1494483206260
finally index：1
Thread-1,执行完成!!!，1494483206390
finally index：0
Thread-0,执行完成!!!，1494483206483
finally index：3
Thread-3,执行完成!!!，1494483206548
finally index：2
Thread-2,执行完成!!!，1494483206567

begin.....................，1494483641348
Thread-0,准备执行!!!，1494483641454
Thread-1,准备执行!!!，1494483641454
Thread-2,准备执行!!!，1494483641454
Thread-3,准备执行!!!，1494483641455
Thread-4,准备执行!!!，1494483641455
end..............，1494483641455
Thread-1,开始执行!!!，1494483641456
Thread-0,开始执行!!!，1494483641456
Thread-2,开始执行!!!，1494483641456
Thread-3,开始执行!!!，1494483641456
Thread-4,开始执行!!!，1494483641456
Thread-3,执行完成!!!，1494483641502
Thread-0,执行完成!!!，1494483641509
Thread-4,执行完成!!!，1494483641545
Thread-1,执行完成!!!，1494483641564
Thread-2,执行完成!!!，1494483641692

begin.....................，1494483670144
Thread-0,准备执行!!!，1494483670268
Thread-1,准备执行!!!，1494483670268
Thread-2,准备执行!!!，1494483670268
Thread-3,准备执行!!!，1494483670268
Thread-4,准备执行!!!，1494483670268
Thread-4,开始执行!!!，1494483670269
Thread-3,开始执行!!!，1494483670269
Thread-2,开始执行!!!，1494483670269
Thread-0,开始执行!!!，1494483670269
Thread-1,开始执行!!!，1494483670269
end..............，1494483670269
Thread-3,执行完成!!!，1494483670399
Thread-2,执行完成!!!，1494483670404
Thread-1,执行完成!!!，1494483670486
Thread-0,执行完成!!!，1494483670536
Thread-4,执行完成!!!，1494483670553

begin.....................
Thread-0,准备执行!!!，1494483690182
end..............
Thread-0,开始执行!!!
Thread-1,准备执行!!!，1494483690183
Thread-2,准备执行!!!，1494483690183
Thread-3,准备执行!!!，1494483690184
Thread-4,准备执行!!!，1494483690184
Thread-0,执行完成!!!
Thread-1,开始执行!!!
Thread-1,执行完成!!!
Thread-2,开始执行!!!
Thread-2,执行完成!!!
Thread-3,开始执行!!!
Thread-3,执行完成!!!
Thread-4,开始执行!!!
Thread-4,执行完成!!!