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https://issues.apache.org/jira/browse/QPID-8546?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17382892#comment-17382892
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ASF subversion and git services commented on QPID-8546:
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Commit eac0ce7970d78215033d6b08241000d5deb3a437 in qpid-broker-j's branch
refs/heads/8.0.x from Alex Rudyy
[ https://gitbox.apache.org/repos/asf?p=qpid-broker-j.git;h=eac0ce7 ]
QPID-8546: Cleanup tests
> Consumer falling behind producer in the BDB HA clusters
> -------------------------------------------------------
>
> Key: QPID-8546
> URL: https://issues.apache.org/jira/browse/QPID-8546
> Project: Qpid
> Issue Type: Bug
> Components: Broker-J
> Affects Versions: qpid-java-broker-8.0.5
> Reporter: Dedeepya
> Priority: Major
>
> With current Qpid Broker versions (up to 8.0.4 including) when BDB HA cluster
> is distributed across different DCs, a consumer throughput falls
> significantly behind the producer . As result, the total system throughput
> (determined by the consumer) can be very low.
> Such behavior is caused by implementation specifics of BDB message store:
> * BDB HA transactions are synchronous for the majority of the nodes. (The
> messaging transaction is committed when majority of the nodes in the cluster
> acknowledge the transaction on their side)
> * The deletion of dequeued messages from the store is synchronous and
> impacted by the DC latency.
> * 2 separate underlying store transactions are used to delete each
> individual message data. Thus, if message consumption happens in
> transactional batches of N, the messages are dequeued from the queue in the
> transacted batch of N messages. However, after message dequeuing, the
> unreferenced message data is deleted using its own store transactions (one
> for content and another for metadata). As result for a batch of N, the store
> runs 1 + N*2 transactions. The N*2 transactions are synchronous and executed
> one after another. If a latency between data centers is high, it adds a
> corresponding delay to each store transaction. As result, the message removal
> takes time. Only after deletion of N messages, the broker sends commit
> confirmation to the client. The message enqueing works differently.
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