缘由

最近在看多线程方法的知识，就有一个问题，如何调试多线程程序？
比如有如下代码，

public class Service {

    private ReentrantReadWriteLock lock = new ReentrantReadWriteLock();

    public void read() {
        try {
            try {
                lock.readLock().lock();
                System.out.println("获得读锁" + Thread.currentThread().getName()
                        + " " + System.currentTimeMillis());
                Thread.sleep(10000);
            } finally {
                lock.readLock().unlock();
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

}

public class ThreadA extends Thread {

    private Service service;

    public ThreadA(Service service) {
        super();
        this.service = service;
    }

    @Override
    public void run() {
        service.read();
    }
}

public class ThreadB extends Thread {

    private Service service;

    public ThreadB(Service service) {
        super();
        this.service = service;
    }

    @Override
    public void run() {
        service.read();
    }
}

public class Run {

    public static void main(String[] args) {

        Service service = new Service();

        ThreadA a = new ThreadA(service);
        a.setName("A");

        ThreadB b = new ThreadB(service);
        b.setName("B");

        a.start();
        b.start();

    }

}

问题

如何通过 debug 这段代码，来验证读写锁在不同线程间是可读的？

方法

按图打上断点，选择 thread，debug main 方法走起

点击图中的位置可切换线程

参考

java 多线程编程核心技术