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https://issues.apache.org/activemq/browse/AMQ-674?page=comments#action_35968 ]
Paul Smith commented on AMQ-674:
--------------------------------
There is a logical queue within our system called "EntityIncrementalIndexer'
(don't think JMS here, just thing in-out pipeline), which updates to mail &
docs in our app are sent as incremental update messages to index nodes.
Each index node, (Index1 & Index2) need to have their own queue, and we use the
Composite Destination feature to clone a message to both destinations:
producer -> JMS -> Index1
-> Index2
The producer is configured to know how many nodes in the cluster, and sends
queue messages via composite destinations, at startup it sets aa variable about
the index node list, and creates a Desitaniotn of the form
"Index1.EntityIncrementalIndexer,Index2.EntityIncrementalIndex". I thought
each Index node would then read from it's own queue, with ActiveMQ pushing the
1 sent message into BOTH queues.
If your immediate thought is "Shouldn't this be done via Durable Subscription
topics?", you are probably right, but I've been bitten by vendors Durable
Subscription implementation before, and thought the Composite Destination
approach might be simpler, and more elegant. (wrong! :))
Now, I'm confused by your comment about RAM. You see I don't believe any of
teh messages sent since we started using 2 nodes in the composite destination
ever got 'missed'. That is from our logs I believe that all messages arrived
and were consumed by the destination. I believe the messages are being
persisted, but not marked as consumed.
> Composite Destination persisted messages never get cleaned up, halt message
> producers
> -------------------------------------------------------------------------------------
>
> Key: AMQ-674
> URL: https://issues.apache.org/activemq/browse/AMQ-674
> Project: ActiveMQ
> Type: Bug
> Components: Broker, Message Store
> Versions: 3.2.1
> Reporter: Paul Smith
> Priority: Blocker
> Fix For: 4.0 RC1
>
>
> well, we've just got bit by something huge.
> Previously we have been shipping messages from producer to consumer via a
> named Queue 'Index2.EntityIncrementalIndexer', where the machine index2 has a
> consumer called "EntityIncrementalIndexer" using persisted messages.
> The design used Composite destinations so that the destination could be:
> "Index1.EntityIncrementalIndexer,Index2.EntityIncrementalIndexer"
> and have the 2 hosts get sent the same message simply, and if one goes down,
> it'll catch up later. This gave us the ability to have a mirrored
> configuration, and go tertiary later if we want simply by adding a new name
> in the composite destation.
> With a single name, this works great, been working fine for months.
> Yesterday we activated the _true_ composite destination, and both machines
> started getting their messages fine.
> no problems so far, BUT, 12 hours later we have noticed that the broker has
> now stopped accepting messages, and a look at the activemq_msgs table shows
> 33228 messages
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