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https://issues.apache.org/jira/browse/AMQ-6239?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15237394#comment-15237394
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ASF subversion and git services commented on AMQ-6239:
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Commit c1b58d3373746eda525e6c3b3ab04eb747e9674b in activemq's branch
refs/heads/master from [~tabish121]
[ https://git-wip-us.apache.org/repos/asf?p=activemq.git;h=c1b58d3 ]
https://issues.apache.org/jira/browse/AMQ-6239
Refactor the iterator implementation in the PrioritizedPendingList to
not copy elements and instead use the level iterators. Add some
additional tests.
> Performance issue in PrioritizedPendingListIterator
> ---------------------------------------------------
>
> Key: AMQ-6239
> URL: https://issues.apache.org/jira/browse/AMQ-6239
> Project: ActiveMQ
> Issue Type: Improvement
> Components: Broker
> Affects Versions: 5.12.2
> Reporter: Martin Lichtin
> Attachments: AMQ-6239-yourkit-1.jpg, PrioritizedPendingList.java.patch
>
>
> Sending and consuming 5000 messages to/from a queue, one can see heavy CPU
> use on the broker side (v 5.12.2).
> Yourkit shows
> PrioritizedPendingList$PrioritizedPendingListIterator.<init>
> as a hot spot method. It calls ArrayList.add(Object) around 12 mio times.
> Situation is that FilePendingMessageCursor.isEmpty() iterates over in-memory
> messages and therefore (as it is a prioritized queue) uses
> PrioritizedPendingListIterator which uses OrderedPendingList.getAsList()
> which overall turns out to be an expensive method as it converts the
> self-managed linked list to a Java ArrayList and then this list is filled
> into another ArrayList managed by PrioritizedPendingListIterator.
> PrioritizedPendingListIterator could be improved to walk the priority lists
> via OrderedPendingList iterators, as these are implemented efficiently.
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