问为什么下面的代码会导致线程争用

EN

public class Test {
Lock lock = new ReentrantLock();

public static void main(String args[]) throws Exception {
    Test t = new Test();
    Second second = t.new Second();
    second.lock = t.lock;
    Thread thread = new Thread(second);
    thread.start();
    Thread.sleep(2000);
    try {
        t.lock.lock();
        System.err.println("got the lock");
    } finally {
        second.shutdown = true;
        t.lock.unlock();
    }
}

private class Second implements Runnable {
    Lock lock;
    volatile boolean shutdown = false;
    int i = 0;

    public void run() {
        while (!shutdown) {
            try {
                lock.lock();
                System.out.println("In second:" + i++);
            } finally {
                lock.unlock();
            }
        }
    }
}