案例代码

package first;

import java.util.concurrent.TimeUnit;

public class DeadLock {
    private static volatile Object lock = new Object();

    public static void main(String[] args) {

        new Thread(() -> {
            test1();
        }).start();
        new Thread(() -> {
            test2();
        }).start();
    }

    public static void test1()  {
        synchronized (lock) {
            System.out.printf("test1");
            try {
                TimeUnit.DAYS.sleep(1);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }

    public static void test2()  {
        synchronized (lock) {
            System.out.printf("test2");
            try {
                TimeUnit.DAYS.sleep(1);
            } catch (InterruptedException e) {
                throw new RuntimeException(e);
            }
        }
    }

}

arthas分析

查看阻塞的线程(当前线程持有锁)

thread -b

表示线程12持有的锁，阻塞了其他的线程

查看阻塞的线程(当前线程等待锁)

thread --state BLOCKED

查看被谁阻塞