java并发控制,使用countDownLatch代替 synchronized,实时通知

    xiaoxiao2025-06-11  38

    有如下代码,当T1加到5的时候,T1通过notify来通知T2.这是<pre name="code" class="java">synchronized 配合notify和wait的版本,只能保证消息通知到了,但不能保证T2可以立即执行,因为T1一直拿着lock的锁,只有加到10才能释放,T2拿到锁的时候,黄花菜都凉了

    /** * wait notfiy 方法,wait释放锁,notfiy不释放锁 * @author alienware * */ public class ListAdd2 { private volatile static List list = new ArrayList(); public void add(){ list.add("bjsxt"); } public int size(){ return list.size(); } public static void main(String[] args) { final ListAdd2 list2 = new ListAdd2(); // 1 实例化出来一个 lock // 当使用wait 和 notify 的时候 , 一定要配合着synchronized关键字去使用 final Object lock = new Object(); final CountDownLatch countDownLatch = new CountDownLatch(1); Thread t1 = new Thread(new Runnable() { @Override public void run() { try { synchronized (lock) { for(int i = 0; i <10; i++){ list2.add(); System.out.println("当前线程:" + Thread.currentThread().getName() + "添加了一个元素.."); Thread.sleep(500); if(list2.size() == 5){ System.out.println("已经发出通知.."); //countDownLatch.countDown(); lock.notify(); } } } } catch (InterruptedException e) { e.printStackTrace(); } } }, "t1"); Thread t2 = new Thread(new Runnable() { @Override public void run() { synchronized (lock) { if(list2.size() != 5){ try { System.out.println("t2进入..."); lock.wait(); //countDownLatch.await(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println("当前线程:" + Thread.currentThread().getName() + "收到通知线程停止.."); throw new RuntimeException(); } } }, "t2"); t2.start(); t1.start(); } }

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