Java一个简单的死锁例子

时间:2022-02-06 17:07:12

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();
	}
}