死锁

1. 代码实现

class HoldLockThread implements Runnable {

    private String lockA;
    private String lockB;
    @Override
    public void run() {
        synchronized (lockA) {
            System.out.println(Thread.currentThread().getName()+"\t 自己持有" + lockA + "\t 尝试获取：" + lockB);
            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            synchronized (lockB) {
                System.out.println(Thread.currentThread().getName()+"\t 自己持有" + lockB + "\t 尝试获取：" + lockA);
            }
        }
    }

    public HoldLockThread(String lockA, String lockB) {
        this.lockA = lockA;
        this.lockB = lockB;
    }
}

/**
 * 死锁是指两个或两个以上的进程在执行过程中，因抢夺资源而造成的一种互相等待的现象
 */
public class DeadLockDemo {

    public static void main(String[] args) {
        String lockA = "lockA";
        String lockB = "lockB";

        new Thread(new HoldLockThread(lockA, lockB), "ThreadAAA").start();
        new Thread(new HoldLockThread(lockB, lockA), "ThreadBBB").start();

    }
}

2. 死锁判定

2.1 查看java进程命令

 linux: ps -ef|grep xxxx
 windows: jps -l

2.2 jstack