Java一个简单的死锁例子

时间:2022-02-06 17:07:18

内容:一个简单的死锁例子,大概的思路:两个线程A和B,两把锁X和Y,现在A先拿到锁X,然后sleep()一段时间,我们知道sleep()是不会释放锁资源的。然后如果这段时间线程B拿到锁Y,也sleep()一段时间的话,那么等到两个线程都醒过来的话,那么将互相等待对方释放锁资源而僵持下去,陷入死锁。flag的作用就是让A和B获得不同的锁。

public class TestDeadLock {

public void run() {
MyThread mt = new MyThread();
new Thread(mt, "张三").start();
new Thread(mt, "李四").start();
}

class MyThread implements Runnable {
private Object o1 = new Object();
private Object o2 = new Object();
private boolean flag = true;


@Override
public void run() {
if (flag) {
flag = false;
synchronized (o1) {
System.out.println(Thread.currentThread().getName() + " have o1");
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (o2) {
System.out.println(Thread.currentThread().getName() + " have o2");
}
}
} else {
flag = true;
synchronized (o2) {
System.out.println(Thread.currentThread().getName() + " have o2");
try {
Thread.sleep(100);
} catch (InterruptedException e) {
e.printStackTrace();
}
synchronized (o1) {
System.out.println(Thread.currentThread().getName() + " have o1");
}
}
}
}
}

public static void main(String[] args) {
new TestDeadLock().run();
}
}