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https://issues.apache.org/jira/browse/ARTEMIS-3049?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17263744#comment-17263744
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ASF subversion and git services commented on ARTEMIS-3049:
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Commit 22dbeb802239ecf365d229364eaf47ce6614d912 in activemq-artemis's branch
refs/heads/master from franz1981
[ https://gitbox.apache.org/repos/asf?p=activemq-artemis.git;h=22dbeb8 ]
ARTEMIS-3049 Simplify PagePosition API
> Reduce live page lookup cost
> ----------------------------
>
> Key: ARTEMIS-3049
> URL: https://issues.apache.org/jira/browse/ARTEMIS-3049
> Project: ActiveMQ Artemis
> Issue Type: Improvement
> Components: Broker
> Affects Versions: 2.16.0
> Reporter: Francesco Nigro
> Assignee: Francesco Nigro
> Priority: Major
> Time Spent: 3h 40m
> Remaining Estimate: 0h
>
> LivePageCacheImpl::getMessage is performing a linked-list-like lookup that
> can be rather slow if compared to an array lookup.
> [https://github.com/apache/activemq-artemis/pull/2494#issuecomment-455086939]
> clearly show the issue with the current implementation.
> The ideal approaches to improve it could be:
> # to replace the chunked list with a copy on write array list
> # to use cursor/iterator API over the chunk list, binding one to each
> consumer, in order to get a linear stride over the live paged messages
> Sadly, the latter approach seems not doable because the live page cache is
> accessed for each message lookup in an anonymous way, making impossible to
> have a 1:1 binding with the consumers, while the former seems not doable,
> because of the array copy cost on appending.
>
> There is still one case that could be improved using the former approach,
> instead, delivering a huge speedup on lookup cost: while reloading live pages.
> A reloaded live page already knows the amount of the loaded live paged
> messages, making possible to store them in a simple array, allowing a much
> faster lookup.
>
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