線程池ThreadPoolExecutor和ExecutorService

線程池ExecutorService和ThreadPoolExecutor
ExecutorService返回的線程池對象的弊端如下：1）FixedThreadPool和SingleThreadPool:允許的請求隊列長度爲Integer.MAX_VALUE，可能會堆積大量的請求，從而導致OOM。2）CachedThreadPool和ScheduledThreadPool:允許的創建線程數量爲Integer.MAX_VALUE，可能會創建大量的線程，從而導致OOM

  1.線程方法類
    public class MyThread extends Thread{
    	@Override
        public void run() {
            System.out.println(Thread.currentThread().getName() + "(自定義)正在執行。。。");
            for (int i = 0; i < 10; i++) {
            	//Timer timer = new Timer();
            	System.out.println(Thread.currentThread().getName()+"=="+i);
    		}
        }	
    }
    
    2.線程池ExecutorService和ThreadPoolExecutor測試類
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import java.util.concurrent.LinkedBlockingQueue;
    import java.util.concurrent.ScheduledThreadPoolExecutor;
    import java.util.concurrent.ThreadPoolExecutor;
    import java.util.concurrent.TimeUnit;
    
    /**
     * 
     * @author zouyang
     * （推薦使用）
     * 創建一個可緩存的線程池。如果線程池的大小超過了處理任務所需要的線程，
     * 那麼就會回收部分空閒（60秒不執行任務）的線程
     *
     */
    
    public class TestCachedThreadPool {
    
    	public static void main(String[] args) {
    	
    		//ExecutorService測試方法
    		//創建一個可重用固定線程數的線程池
            ExecutorService pool = Executors.newCachedThreadPool();
            
			//創建一個可重用固定線程數的線程池
        	//ExecutorService pool = Executors.newFixedThreadPool(1);//指定個數

            //創建實現了Runnable接口對象，Thread對象當然也實現了Runnable接口
           /* Thread t1 = new MyThread();
            Thread t2 = new MyThread();
            Thread t3 = new MyThread();
            Thread t4 = new MyThread();
            Thread t5 = new MyThread();        
            //將線程放入池中進行執行
            pool.execute(t1);
            pool.execute(t2);
            pool.execute(t3);
            pool.execute(t4);
            pool.execute(t5);
            */
            for (int i = 0; i < 5; i++) {
            	//Thread t1 = new MyThread();
            	//pool.execute(t1);
    		}
            pool.shutdown();//關閉線程池
    
    		//ThreadPoolExecutor測試方法
            System.out.println("ThreadPoolExecutor線程池");
            ThreadPoolExecutor tpe = new ThreadPoolExecutor(5, 10, 10, TimeUnit.MILLISECONDS, new LinkedBlockingQueue<>(10));
            for (int i = 0; i < 5; i++) {
            	Thread t1 = new MyThread();
            	tpe.execute(t1);
    		}
            tpe.shutdown();//關閉線程池
            
    	}
    
    }