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Posted to issues@activemq.apache.org by "Clebert Suconic (Jira)" <ji...@apache.org> on 2021/02/09 21:23:05 UTC
[jira] [Closed] (ARTEMIS-3049) Reduce live page lookup cost
[ https://issues.apache.org/jira/browse/ARTEMIS-3049?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Clebert Suconic closed ARTEMIS-3049.
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Fix Version/s: 2.17.0
Resolution: Fixed
> 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
> Fix For: 2.17.0
>
> Time Spent: 3h 50m
> 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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