Question

我正在做并发问题的家庭作业。我有很多线程在做特定的事情，还有一个方法决定这些线程什么时候可以访问资源。

所以我的班级看起来像这样：

public class Boss extends ReentrantLock implements Runnable {

    Lock access = new ReentrantLock();
    Condition canTakeOff = access.newCondition();
    Condition canLand = access.newCondition();

    public void accessToLanding(){
            access.lock();
            try{
                if(getWaitQueueLength(canTakeOff) > 0){
                    canTakeOff.notifyAll();
                } else if {
                 /* some other cases */
                }
            } catch (InterruptedException e){
                e.printStackTrace();
            } finally {
                access.unlock();
            }
    }

    public void run(){
        accessToLanding();
    }

    /* Methods which are called by objects of a different class, 
    they are awaiting for the signal from accessToLanding.*/
}

我收到了错误：

Exception in thread "Thread-0" java.lang.IllegalArgumentException: Not owner
at java.util.concurrent.locks.AbstractQueuedSynchronizer.getWaitQueueLength(AbstractQueuedSynchronizer.java:1789)
at java.util.concurrent.locks.ReentrantLock.getWaitQueueLength(ReentrantLock.java:720)

我已经检查了文档并且它说当“给定条件与此锁无关”时getWaitQueueLength抛出IllegalArgumentException但是根据我的理解，它与我的代码相关联。有人能帮助我吗？

Answer 1

当您调用

时

getWaitQueueLength(canTakeOff)

你正在打电话

this.getWaitQueueLength(canTakeOff)

其中此是您的Boss实例。尽管 canTakeOff 已声明有成员，但它不属于属于Boss，它是从 access 获得的条件

我认为您必须稍微改变上述行并使用

access.getWaitQueueLength(canTakeOff)

更多信息：Javadoc getWaitQueueLength throws IllegalArgumentException

getWaitQueueLength抛出IllegalArgumentException：不是所有者

1 个答案: