java-doc-suspend和resume

suspend和resume

容易写出死锁的代码 。不在建议使用

public class LearnSuspend1 {
    public static Object iceCream = null;

    public static void main(String[] args) throws Exception {
        LearnSuspend1 sup = new LearnSuspend1();
        sup.suspendResumeTest();
        //sup.test2_SyncDeadLock();
        //sup.test3_OrderDeadLock();
    }

    // 正常运行
    public void suspendResumeTest() throws Exception {
        // 启动线程
        Thread consumerThread = new Thread(() -> {
            if (iceCream == null) {
                System.out.println("没有冰激凌， 小朋友不开心， 等待...");
                Thread.currentThread().suspend();
            }

            System.out.println("小朋友买到冰激凌， 开心回家");
        });
        consumerThread.start();
        Thread.sleep(3000L); // 3秒之后
        iceCream = new Object(); //店员做好了冰激凌
        consumerThread.resume(); //通知小朋友
        System.out.println("通知小朋友");
    }

    // 死锁1
    public void test2_SyncDeadLock() throws Exception {
        //开启一个线程， 代表小朋友
        Thread consumerThread = new Thread(() -> {
            if (iceCream == null) { // 若没冰激凌
                System.out.println("没有冰激凌， 小朋友不开心， 等待...");
                synchronized (this.iceCream) { // 小朋友把钥匙拿着
                    Thread.currentThread().suspend(); //睡着了
                }
            }
            System.out.println("小朋友买到冰激凌， 开心回家");
        });
        consumerThread.start();
        Thread.sleep(3000L); // 3秒之后，
        iceCream = new Object(); // 店员做了一个冰激凌
        synchronized (this) { // 拿到小朋友加的钥匙， 才能进去叫他
            consumerThread.resume();
        }
        System.out.println("通知小朋友");
    }

    // 死锁2
    public void test3_OrderDeadLock() throws Exception {
        //开启一个线程， 代表小朋友
        Thread consumerThread = new Thread(() -> {
            if (iceCream == null) { // 若没冰激凌
                try {
                    Thread.sleep(5000L); // 模拟小朋友出去玩
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                System.out.println("没有冰激凌， 小朋友不开心， 等待...");
                Thread.currentThread().suspend(); // suspend在resume之前
            }
            System.out.println("小朋友买到冰激凌， 开心回家");
        });
        consumerThread.start();
        Thread.sleep(3000L); // 3秒之后
        iceCream = new Object(); //店员做了一个冰激凌
        consumerThread.resume(); //喊了一声， 小朋友根本没在家睡觉
        System.out.println("通知小朋友");
    }
}