线程池以及计数器的使用简单示例-白红宇

线程池以及计数器的使用简单示例

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发布时间：2019-06-29

本文共 5219 字，大约阅读时间需要 17 分钟。

　　项目中用到夜间跑批的问题，考虑使用多线程同时跑批，每次拿出100批数据，创建定长线程池，长度

为10，然后将这100批数据分成10份，10个线程各自处理自己的那一部分，每当有一个线程处理完成后就会

进入等待，计数器减1，直到计数器为0时，说明每个线程都完成了自己的工作，然后进入主线程执行。

1：创建定长线程池

1 public static final int THREAD_NUM = 10;2     public ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_NUM);// 创建10个线程放入线程池内

2：创建线程任务

1 public class myRun implements Runnable{ 2          3         private List
      
       > tmpList; 4         private int threadCount; 5         private CountDownLatch countdown; 6         private int oneThreadCount; 7          8         public myRun(List
       
        
         > tmpList, int threadCount, 9                 CountDownLatch countdown,int oneThreadCount) {10             super();11             this.tmpList = tmpList;12             this.threadCount = threadCount;13             this.countdown = countdown;14             this.oneThreadCount = oneThreadCount;15         }16 17         @Override18         public void run() {19             for (int i = threadCount * oneThreadCount; i < (threadCount + 1) * oneThreadCount20                     && i < tmpList.size(); i++) {21                 System.out.println(Thread.currentThread().getName()+ "#" + i);22                 System.out.println(tmpList.get(i));23             }24             countdown.countDown();// 每个子线程结束后进行线程减125             System.out.println(Thread.currentThread().getName()26                     + "##线程结束------------------------");27             System.out.println("----------------剩余的线程个数:"28                     + countdown.getCount());29         }30         31     }

3：主线程执行任务

public void doHandler() {        try {            List
      
       > list = getList();            final CountDownLatch countdown = new CountDownLatch(THREAD_NUM);// 子线程数            int oneThreadCount = list.size()/THREAD_NUM + 1;            for (int num = 0; num < THREAD_NUM; num++) {
   // 开启线程个数                System.out.println("----------------共有的线程个数:" + countdown.getCount());                threadPool.execute(new myRun(list,num,countdown,oneThreadCount));            }            countdown.await();// 这里进行同步等待,等所有子线程结束后，执行 countdown.await()后面的代码            System.out.println("##结束等待------------------------");        } catch (InterruptedException e) {            e.printStackTrace();        } finally {            threadPool.shutdown();        }    }    public static List
       
        
         > getList() {        List
         
          
           > resultList = new ArrayList
           
            
             >(); for (int i = 0; i < 99; i++) { Map
             
               tmpMap = new HashMap
              
               (); tmpMap.put("id", 1); tmpMap.put("name", "rose"); tmpMap.put("salary", 10000); resultList.add(tmpMap); } return resultList; }

4：整个代码如下

1 package com.hlcui.threadpool; 2  3 import java.util.ArrayList; 4 import java.util.HashMap; 5 import java.util.List; 6 import java.util.Map; 7 import java.util.concurrent.CountDownLatch; 8 import java.util.concurrent.ExecutorService; 9 import java.util.concurrent.Executors;10 11 public class ThreadCountDemo {12     public static final int THREAD_NUM = 10;13     public ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_NUM);// 创建10个线程放入线程池内14 15     public void doHandler() {16         try {17             List
      
       > list = getList();18             final CountDownLatch countdown = new CountDownLatch(THREAD_NUM);// 子线程数19             int oneThreadCount = list.size()/THREAD_NUM + 1;20             for (int num = 0; num < THREAD_NUM; num++) {
   // 开启线程个数21                 System.out.println("----------------共有的线程个数:" + countdown.getCount());22                 threadPool.execute(new myRun(list,num,countdown,oneThreadCount));23             }24             countdown.await();// 这里进行同步等待,等所有子线程结束后，执行 countdown.await()后面的代码25             System.out.println("##结束等待------------------------");26         } catch (InterruptedException e) {27             e.printStackTrace();28         } finally {29             threadPool.shutdown();30         }31     }32 33     public static List
       
        
         > getList() {34         List
         
          
           > resultList = new ArrayList
           
            
             >();35 for (int i = 0; i < 99; i++) {36 Map
             
               tmpMap = new HashMap
              
               ();37 tmpMap.put("id", 1);38 tmpMap.put("name", "rose");39 tmpMap.put("salary", 10000);40 resultList.add(tmpMap);41 }42 return resultList;43 }44 45 public class myRun implements Runnable{46 47 private List
               
                
                 > tmpList;48 private int threadCount;49 private CountDownLatch countdown;50 private int oneThreadCount;51 52 public myRun(List
                 
                  
                   > tmpList, int threadCount,53 CountDownLatch countdown,int oneThreadCount) {54 super();55 this.tmpList = tmpList;56 this.threadCount = threadCount;57 this.countdown = countdown;58 this.oneThreadCount = oneThreadCount;59 }60 61 @Override62 public void run() {63 for (int i = threadCount * oneThreadCount; i < (threadCount + 1) * oneThreadCount64 && i < tmpList.size(); i++) {65 System.out.println(Thread.currentThread().getName()+ "#" + i);66 System.out.println(tmpList.get(i));67 }68 countdown.countDown();// 每个子线程结束后进行线程减169 System.out.println(Thread.currentThread().getName()70 + "##线程结束------------------------");71 System.out.println("----------------剩余的线程个数:"72 + countdown.getCount());73 }74 75 }76 }