java 多线程(ThreadPoolExecutor (补充))

import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;


public class App {
    
    private ThreadPoolExecutor threadpool;
    
    public App(){
        /*参数依次是:
        corePoolSize     - 池中所保存的线程数,包括空闲线程。
        maximumPoolSize - 池中允许的最大线程数。
        keepAliveTime     - 当线程数大于核心时,此为终止前多余的空闲线程等待新任务的最长时间。
        unit             - keepAliveTime 参数的时间单位。
        workQueue         - 执行前用于保持任务的队列。此队列仅由保持 execute 方法提交的 Runnable 任务。
        handler         - 由于超出线程范围和队列容量而使执行被阻塞时所使用的处理程序。*/
        
        //规则:
        //1. 池中线程数量小于corePoolSize, 即使存在空闲线程,也启动新线程处理新任务;
        //2. 池中显成熟等于corePoolSize,则添加至workQueue;
        //3. 若此时连workQueue也满,但线程数小于maximumPoolSize, 则添加新线程处理新任务;
        //4. 若超过maximumPoolSize 则调用handler 处理
        //   DiscardOldestPolicy -> 放弃最末的处理请求   
        threadpool = new ThreadPoolExecutor(2,3, 10, TimeUnit.
                SECONDS, new ArrayBlockingQueue(2),
                new ThreadPoolExecutor.DiscardOldestPolicy());
    }
    
    public void subMit(final int value){
        threadpool.execute(new Runnable(){

            @Override
            public void run() {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.print(value + "_hello\r\n");
            }    
        });
    }
    
    public void shutdown() {  
       threadpool.shutdown();  
    } 
    
    
    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        App app = new App();
        for(int i = 0; i < 5;i++){
            app.subMit(i);
        }
        //输出:当threadpool = new ThreadPoolExecutor(2,3, 10, TimeUnit.
        //SECONDS, new ArrayBlockingQueue(1), 
        //3_hello
        //1_hello
        //0_hello
        //4_hello
        
        //输出:当threadpool = new ThreadPoolExecutor(2,3, 10, TimeUnit.
        //SECONDS, new ArrayBlockingQueue(2), 
        //0_hello
        //1_hello
        //4_hello
        //3_hello
        //2_hello
            
        app.shutdown();
    }

}

 

    原文作者:Fredric_2013
    原文地址: https://www.cnblogs.com/Fredric-2013/p/4530665.html
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