代码如下

package lock;

public class DeadLock {

    public static Integer l = 5;
    public static Integer r = 6;

    public static void main(String[] args) {
        new Thread(new Thread4()).start();
        new Thread(new Thread3()).start();
    }
}

class Thread3 implements Runnable{

    @Override
    public void run() {

        synchronized (DeadLock.l){
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (DeadLock.r){
                System.out.println("Thread3 is running");
            }
        }
    }
}

class Thread4 implements  Runnable{
    @Override
    public void run() {
        synchronized (DeadLock.r){
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (DeadLock.l){
                System.out.println("Thread4 is running");
            }
        }
    }
}

测试结果

利用jdk自带的jvisualvm进行测试，jdk9之后好像就不和jdk捆绑在一起了（在命令行输入jvisualvm）

两个线程互相拥有对方想要的东西

死锁问题

原文：https://www.cnblogs.com/cstdio1/p/12240815.html