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From "Thomas Riccardi (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AMQCPP-445) Prefetch_size = 0 and failover: consumer blocked in receive() when broker restarts
Date Tue, 11 Dec 2012 17:03:22 GMT
Thomas Riccardi created AMQCPP-445:
--------------------------------------

             Summary: Prefetch_size = 0 and failover: consumer blocked in receive() when broker
restarts
                 Key: AMQCPP-445
                 URL: https://issues.apache.org/jira/browse/AMQCPP-445
             Project: ActiveMQ C++ Client
          Issue Type: Bug
          Components: CMS Impl
    Affects Versions: 3.4.4
         Environment: Ubuntu 10.04/12.04 x86_64, ActiveMQ 5.5.0/5.7.0
            Reporter: Thomas Riccardi
            Assignee: Timothy Bish


With prefetch_size=0, the consumer.receive() sends a pull request to the broker, and then
waits on dequeue() for a new message.
With failover, if the broker is restarted after having received the pull request, then the
consumer is blocked indefinitely in receive(), and the broker never sends messages to it.


Here is the stack of the blocked consumer. It never returned from the first call to receive().
{quote}
#0  pthread_cond_wait@@GLIBC_2.3.2 ()
at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f2528c8fdd7 in decaf::internal::util::concurrent::ConditionImpl::wait (condition=0x118a024)
at decaf/internal/util/concurrent/unix/ConditionImpl.cpp:101
#2  0x00007f2528b23075 in activemq::core::SimplePriorityMessageDispatchChannel::dequeue (this=0x1181b40,
timeout=-1)
at activemq/core/SimplePriorityMessageDispatchChannel.cpp:77
#3  0x00007f2528ad6d78 in activemq::core::ActiveMQConsumer::dequeue (this=0x11892d0, timeout=-1)
at activemq/core/ActiveMQConsumer.cpp:553
#4  0x00007f2528adbef1 in activemq::core::ActiveMQConsumer::receive (this=0x11892d0) at activemq/core/ActiveMQConsumer.cpp:601
{quote}

It seems the failover mechanism never notifies the consumer->internal->unconsumedMessages
fifo, so the consumer stays blocked on dequeue(), while the new broker doesn't know the consumer
has sent a pull request.

I haven't found any use of the callback transportResumed() from the failover transport.
A solution would be to use this callback to notifyAll() on all consumers internal queues.

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