闭锁初尝试

package JavaDay6_02;

import java.util.concurrent.CountDownLatch;

/**
 * @author myvina@qq.com
 * @date 18-6-2  上午8:55
 */

//在计时测试中使用闭锁来启动和停止线程
public class Demo1 {
    public long timeTasks(int nThreads, final Runnable task) throws InterruptedException {
        final CountDownLatch startGate = new CountDownLatch(1);
        final CountDownLatch endGate = new CountDownLatch(nThreads);

        for(int i = 0; i < nThreads; i++) {
            Thread t = new Thread() {
                @Override
                public void run() {
                    try {
                        //线程开始运行，此处等待闭锁打开
                        startGate.await();
                        try {
                            task.run();
                        } finally {
                            //对endGate的闭锁计数器减一
                            endGate.countDown();
                        }
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            t.start();
        }
        long start = System.nanoTime();
        System.out.println("开始执行...");
        //startGate的计数器减一，所有线程开始执行
        startGate.countDown();
        //等待最后一个线程执行完
        endGate.await();
        System.out.println("结束执行...");
        long end = System.nanoTime();
        return end - start;
    }

    public static void main(String[] args) {
        Demo1 demo1= new Demo1();
        Runnable task = new Runnable() {
            @Override
            public void run() {
                long sum = 0L;
                for(int i = 0; i < Integer.MAX_VALUE; i++) {
                    sum += i;
                }
                System.out.println(sum);
            }
        };

        try {
            System.out.println("运行时间为： " + demo1.timeTasks(10, task));
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

    运行结果为：