Question

我们在WebLogic 12c中运行的应用程序正在从排队系统中检索消息，我们从中检索消息的队列被配置为FIFO。我们使用Spring来配置检索功能，容器（org.springframework.jms.listener.DefaultMessageListenerContainer）和消息监听器（org.springframework.jms.core.support.JmsGatewaySupport）都是单例。此外，该容器默认将WorkManager配置为任务执行程序。为了保证消息按预期的顺序（它们如何发送到队列的顺序）处理，我们在侦听器中使用ReentrantLock，我们期望逐个检索和处理消息。监听器代码如下：

public class JmsReceiveAdapterImpl extends JmsGatewaySupport implements SessionAwareMessageListener {
    private final ReentrantLock lock = new ReentrantLock(true);
    [...]
    public void onMessage(Message rcvMessage, Session session) throws JMSException {
        lock.lock();
        logger.warn("Lock has been acquired by thread: " + Thread.currentThread().getId());
        try {
            [...]
        } finally {
            logger.warn("Lock is going to be released by thread: " + Thread.currentThread().getId());
            lock.unlock();
        }
    }
}

即使两个消息以正确的顺序放在队列中，并且它们按照该顺序被消耗（回想一下队列是FIFO），不知何故，应用程序并行处理这两条消息，因为它显示在以下日志块中：

    Lock has been acquired by thread: 28
    Backout count: 1
    Message 1 / 1 received from XXX Message ID1 received.
    Lock has been acquired by thread: 54 
    Backout count: 1
    Message 1 / 1 received from XXX Message ID2 received.
    ***** ERROR *****
    Lock is going to be released by thread: 54
    Lock is going to be released by thread: 28

为什么我们会获得此行为？有什么想法吗？

非常感谢你。

Answer 1

更改

logger.warn("Lock has been acquired by thread: " + Thread.currentThread().getId());

到

logger.warn("Lock has been acquired by thread: " + Thread.currentThread().getId() + " And Object " + System.identityHashCode(this));

您可能会看到System.identityHashCode将是两个不同的数字。如果它是同一个对象，则identityHashCode将是相同的。如果它们不同，那意味着它们是不同的对象。

它告诉您的是，有多个ReentrantLock实例，并且不支持差异实例上的互斥。

线程获取已由其他线程获取的ReentrantLock

1 个答案: