JVM优化之使用Jstack命令查找JVM死锁

JVM优化之使用Jstack命令查找JVM死锁

示例代码

public class DeadLockDemo {

    private static Object lock1 = new Object();
    private static Object lock2 = new Object();

    public static void main(String[] args) {
        new Thread(() -> {
            synchronized (lock1) {
                try {
                    System.out.println("thread1 begin");
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                }
                synchronized (lock2) {
                    System.out.println("thread1 end");
                }
            }
        }).start();

        new Thread(() -> {
            synchronized (lock2) {
                try {
                    System.out.println("thread2 begin");
                    Thread.sleep(5000);
                } catch (InterruptedException e) {
                }
                synchronized (lock1) {
                    System.out.println("thread2 end");
                }
            }
        }).start();
    }
}

使用下面的命令输出线程信息

jstack <pid>

"Thread-1" 线程名

prio=5 优先级=5

tid=0x0000028ae51d6000 线程id

nid=0x8778 线程对应的本地线程标识nid

java.lang.Thread.State: BLOCKED 线程状态

通过输出结果，可以看到有一个线程死锁，Thread-0和Thread-1在进行资源的竞争，同时也输出了资源竞争代码所在行。