多线程处理任务案例（同步锁+StopWatch+CountDownLatch）

拼搏现实的明天。 2022-05-27 03:13 50阅读 0赞

今天抽空写了一个通过spring线程池来实现多线程处理任务的性能问题。这个代码相对简单，文字描述相对较少。大家有疑问可以回复。

## 1、任务线程代码 ##

package com.yufeicms.test;
    
    import java.util.concurrent.CountDownLatch;
    
    public class MyThread implements  Runnable{
    
        private  int  currentIndex;//当前待处理的任务下标
    
        private  int  maxIndex;//最大小标
    
        private int[] idArr;//任务数据ID
    
        private Object  obj = new Object();//做同步锁
    
        private CountDownLatch countDownLatch;//监听所有线程任务执行完毕
    
        public MyThread(int[] idArr, CountDownLatch countDownLatch){
            this.maxIndex = idArr.length-1;
            this.idArr = idArr;
            this.countDownLatch = countDownLatch;
        }
        @Override
        public void run() {
             while (true){
                 if(currentIndex > maxIndex){
                     break;
                 }
                 int  id;
                 synchronized (obj){
                     if(++currentIndex > maxIndex){
                         break;
                     }
                 }
                 id = idArr[currentIndex];
                 handle(id);
             }
            countDownLatch.countDown();
        }
    
        private  void  handle(int id){
            System.out.println("开始处理"+Thread.currentThread().getName()+"文章ID："+id);
            try{
                Thread.sleep(1000);//模拟处理任务
            }catch (Exception e){
                e.printStackTrace();
            }
            System.out.println("结束处理"+Thread.currentThread().getName()+"文章ID："+id);
        }
    }

## 2、测试类代码 ##

package com.yufeicms.test;
    
    import org.apache.commons.lang3.time.StopWatch;
    
    import java.util.concurrent.CountDownLatch;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    
    public class Test {
        public static void main(String[] args) throws InterruptedException {
            int nThreads = 10;
            ExecutorService pool = Executors.newFixedThreadPool(nThreads);
            CountDownLatch countDownLatch = new CountDownLatch(nThreads);
            StopWatch stopWatch = new StopWatch();
            int[]  idArr = new int[100];
            for(int i =0 ; i< 100; i++){
                idArr[i]=i+10000;
            }
            stopWatch.start();
            MyThread myThread = new MyThread(idArr,countDownLatch);
            for(int i=0;i<nThreads;i++){
                pool.execute(new Thread(myThread));
            }
            countDownLatch.await();
            stopWatch.stop();
            System.out.println("执行完所有任务所需时间："+stopWatch.getTime()/1000+"秒");
            pool.shutdown();
        }
    }

## 3、测试结果大致如下： ##

![70][]

## 4、总结 ##

1、由于任务并未做具体事情，通过Thread.sleep()方法，所以cpu资源是让出来了的。所以线程数\*耗时=任务数；

2、代码中使用stopwatch用来计时；

3、代码中使用CountDownLatch来保证时间的准确性。

[70]: /images/20220527/6a75df172ae64185a7d97f452616b146.png