死锁问题之查看排除死锁

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

        new Thread(new deadlockTest(lockA, lockB), "t1").start();
        new Thread(new deadlockTest(lockB, lockA), "t2").start();
    }

}

class deadlockTest implements Runnable {
    private String lockA;
    private String lockB;

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

    @Override
    public void run() {
        synchronized (lockA) {
            System.out.println(Thread.currentThread().getName() + "is " + lockA + "  want  " + lockB);


            try {
                TimeUnit.SECONDS.sleep(2);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            synchronized (lockB) {
                System.out.println(Thread.currentThread().getName() + "is " + lockB + "  want  " + lockA);
            }
        }
    }
}

代码会造成死锁问题：

这个时候我们可以查看堆栈里面的情况：
使用jps-l查看进程号

得到进程号为14100

使用jstack 进程号查看堆栈的情况


往下面翻可以看见t1和t2两个线程各自都等着对面的，
所有互相交叉，形成死锁