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From Eric Van Dewoestine <>
Subject Re: Issue creating a distributed queue using store and forward.
Date Thu, 08 Oct 2009 17:35:58 GMT
Thanks for the link. Did you try applying that patch? If so did it
resolve your issue?

I'll give the patch a shot, but the note in the ticket regarding
failures for large message counts and Joe's warnings make me a little
apprehensive.  I'll update my findings as soon as I get a chance to
test it out.

On Thu, Oct 8, 2009 at 10:17 AM, farshad <> wrote:
> Hi Eric,
> I think you and I have run into the same problem.  Please check below.
> Farshad
> Eric Van wrote:
>> ActiveMQ 5.3.0_SNAPSHOT (Sep 8th according to the snapshots listing)
>> I'm running into an issue with the store and forward feature of
>> activemq, which I using in an attempt to create a highly available
>> distributed queue.  I'm trying to figure out if the issue is a
>> misconfiguration on my part, expected behavior of activemq, or a bug.
>> The summary of the problem is that given 2 brokers, B1 and B2, which
>> each have one consumer, C1 and C2, which are subscribed to the same
>> queue.  If I stop a consumer on one of the brokers, the pending
>> messages from that broker are not always forwarded to the other broker
>> which still has a consumer, leading to those messages getting
>> indefinitely stuck.
>> The steps I use to reproduce this scenario are as follows (Note: all
>> producing and consuming is performed over the stomp transport):
>> Couple notes about the consumers:
>> - they have a prefetchSize of 40
>> - the processing of messages can take some time, so for the purposes
>>   of this exercise, I've created a simple consumer that sleeps for 10
>>   seconds before sending the message ack (using client-individual ack
>>   mode)
>> 1. start both brokers (B1 and B2). The consumers (C1 and C2) are not
>>    yet running.
>> 2. produce a few thousand messages to B1
>>    Note: B1 now has a few thousand pending messages and B2 has 0.
>> 3. start consumer C2 (listing for messages from B2)
>>    Note: messages are are successfully received and begin processing
>>    (monitoring the brokers shows pending messages decreasing). Now B2
>>    has all the pending messages and B1 has 0.
>> 4. start consumer C1 (listing for messages from B1)
>>    Note: no messages are received, which is another issue I have since
>>    B2 now has thousands of pending messages which C1 could help
>>    process, but instead sits idle while C2 is forced to handle all the
>>    messages.
>> 5. stop consumer C2
>>    Note: now I have thousands of messages sitting on B2 and 0 on B1
>>    where a C1 is alive and ready to handle them.  So at this point,
>>    despite having a consumer running, thousands of messages are stuck
>>    in the queue.
>> 6. stop consumer C1
>>    Note: now I have no consumers.  Stopping and restarting C1 has no
>>    effect on the pending messages sitting on B1's queue.
>> 7. stop both brokers
>> 8. start B1, then start B2
>> 9. start C1
>>    Note: now all messages have migrated from B2 to B1 and C1 is again
>>    processing messages.
>> So after step 5, the only way to recover from the stuck messages is to
>> restart the brokers.
>> Below is my current connector config which I have on both brokers.
>> I've tried playing with the various properties of the connector, but
>> it seems as though no matter what I try the above scenario continues
>> to occur.
>> <networkConnector
>>     name="default-nc"
>>     uri="multicast://default?group=${}"
>>     dynamicOnly="true"
>>     networkTTL="25"
>>     suppressDuplicateQueueSubscriptions="true"/>
>> So, is this an activemq bug? Am I mis-using activemq? Is there some
>> other way to achieve a highly available distributed queue?
>> Any help in this regard is greatly appreciated.
>> --
>> eric
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