多线程分批处理集合中的元素【我】

 

 

package cn.nest;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.util.ArrayList;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

public class MySemaphore2 {

    //统计实际一共处理了多少个数据
    static int sum = 0;
    
    public static void main(String[] args) throws IOException, InterruptedException {
        
        //待处理集合
        ArrayList<Integer> list = new ArrayList<>();
        //定义待处理集合中元素数量
        int dataSize = 35;
        //拼装数据
        for (int i = 0; i < dataSize; i++) {
            list.add(i);
        }
        //打印集合原始数据和长度
        System.out.println("list: "+list);
        System.out.println("list size: "+list.size());
        
        //定义多线程
        final Semaphore semaphore = new Semaphore(5);
        ExecutorService exec = Executors.newCachedThreadPool();
        
        //记录开始时间
        final long start = System.currentTimeMillis();
        
        //定义一次执行多少个数据
        int onceNum = 10;
        //计算需要执行多少次
        int executeNum  = (int) Math.ceil(dataSize / onceNum  +1);
        System.out.println("num: "+executeNum);
        
        for (int i = 0; i < executeNum; i++) {
            //为了在run方法中使用变量i的值，需要在这里重新定义
            Integer n = i;
            
            //定义线程任务
            Runnable task = new Runnable() {
                @Override
                public void run() {
                    try {
                        semaphore.acquire();//获取信号量
                       
//                        System.out.println(1000*i+"~"+(1000*i+1000));
                        //遍历，计算当前需要处理的这批数据的角标
                        for (int j = onceNum*n; j < (onceNum*n+onceNum); j++) {
                            //当前处理的数据
                            System.out.println(Thread.currentThread().getName()+" --: "+list.get(j));
                            sum++;
                        }
                        //开始休息
                        System.out.println(Thread.currentThread().getName()+" 休息一分钟");
                        Thread.sleep(1000*60);
                        
                        semaphore.release();//释放信号量
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            //提交任务（开启线程）
            exec.submit(task);
        }
        
        exec.shutdown();
        //判断所有线程都结束
//        exec.awaitTermination(1, TimeUnit.HOURS); //用这个也行
        while (true) {
            if (exec.isTerminated()) {
                System.out.println("-----------------所有的子线程都结束了！");
                break;
            }
            Thread.sleep(1000);
        }
        //后续逻辑
        final long end = System.currentTimeMillis();
        System.out.println("consumer time ： "+(end-start));//耗时
        System.out.println("sum: "+sum);//一共处理了多少条数据
        
    }
    
    public static void main1(String[] args) throws IOException, InterruptedException {
        
        
        final File stream = new File("c:\\temp\\stonefeng\\stream.txt");
        final OutputStream os = new FileOutputStream(stream);
        final OutputStreamWriter writer = new OutputStreamWriter(os);
        
        
        final Semaphore semaphore = new Semaphore(10);
        ExecutorService exec = Executors.newCachedThreadPool();
        
        final long start = System.currentTimeMillis();
        for (int i = 0; i < 10000000; i++) {
            final int num = i;
            Runnable task = new Runnable() {
                @Override
                public void run() {
                    try {
                        semaphore.acquire();
                        writer.write(String.valueOf(num)+"\n");
                        semaphore.release();
                    } catch (IOException e) {
                        e.printStackTrace();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            };
            exec.submit(task);
        }
        exec.shutdown();
        exec.awaitTermination(1, TimeUnit.HOURS);
        writer.write("---END---\n");
        writer.close();
        System.out.println("ËùÓеÄ×ÓÏ̶߳¼½áÊøÁË£¡");  
        final long end = System.currentTimeMillis();
        System.out.println(end-start);
    }
    
    public static void main2(String[] args) {
        
        int size = 1000;
            int num  = (int) Math.ceil(3500 / size  +1);
            System.out.println("num: "+num);
            
        for (int i = 0; i < num; i++) {
            System.out.println(1000*i+"~"+(1000*i+1000));
        }
    }
}