线程池中利用多线程大量插入数据

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import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class test {


    public static void exec(List<String> list) throws InterruptedException {
        //一个线程处理300条数据
        int count = 300;
        //数据集合大小
        int listSize = list.size();
        //开启的线程数
        int runSize =  listSize%count > 0 ?  ((listSize/count)+1) : (listSize/count);
        //存放每个线程的执行数据
        List<String> newlist = null;
        //创建一个线程池，数量和开启线程的数量一样
        ExecutorService executor = Executors.newFixedThreadPool(runSize);
        //创建两个个计数器
        CountDownLatch begin = new CountDownLatch(1);
        CountDownLatch end = new CountDownLatch(runSize);
        //循环创建线程
        for (int i = 0; i < runSize; i++) {
            //计算每个线程执行的数据
            if ((i + 1) == runSize) {
                int startIndex = (i * count);
                int endIndex = list.size();
                newlist = list.subList(startIndex, endIndex);
            } else {
                int startIndex = (i * count);
                int endIndex = (i + 1) * count;
                newlist = list.subList(startIndex, endIndex);
            }
            //线程类
            MyThread mythead = new MyThread(newlist, begin, end);
            //这里执行线程的方式是调用线程池里的executor.execute(mythead)方法。
            executor.execute(mythead);
        }

        begin.countDown();
        end.await();

        //执行完关闭线程池
        executor.shutdown();
    }


    //测试
    public static void main(String[] args) {
        List<String> list = new ArrayList<String>();
        //数据越大线程越多
        for (int i = 0; i < 3000000; i++) {
            list.add("hello" + i);
        }
        try {
            exec(list);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

import java.util.List;
import java.util.concurrent.CountDownLatch;

public class MyThread implements Runnable {
    private List<String> list;
    private CountDownLatch begin;
    private CountDownLatch end;

    //创建个构造函数初始化 list,和其他用到的参数
    public MyThread(List<String> list, CountDownLatch begin, CountDownLatch end) {
        this.list = list;
        this.begin = begin;
        this.end = end;
    }

    @Override
    public void run() {
        try {
            for (int i = 0; i < list.size(); i++) {
                //这里还要说一下，由于在实质项目中，当处理的数据存在等待超时和出错会使线程一直处于等待状态
                //这里只是处理简单的，
                //分批 批量插入
            }

            //执行完让线程直接进入等待
            begin.await();
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } finally {
            //这里要注意了，当一个线程执行完了计数要减一，不然这个线程会被一直挂起
            // end.countDown()，这个方法就是直接把计数器减一的
            end.countDown();
        }
    }

}