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https://issues.apache.org/activemq/browse/AMQ-1082?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rob Davies reassigned AMQ-1082:
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Assignee: Rob Davies
> Improve Kaha freeList
> ---------------------
>
> Key: AMQ-1082
> URL: https://issues.apache.org/activemq/browse/AMQ-1082
> Project: ActiveMQ
> Issue Type: Improvement
> Affects Versions: 4.2.0
> Reporter: [EMAIL PROTECTED]
> Assigned To: Rob Davies
>
> This is in kaha.impl.index.IndexManager.java.
> The index currently maintains an in-memory free list. Each entry costs at
> least 51 bytes of RAM. Issue is that the more free space that there is in
> the file, the more RAM is used (oddly enough).
> I am worried about the case where suppose a producer enqueues millions of
> messages and then stops. Now, suppose a consumer dequeues all of the
> messages (no producers are starting up during this time, so the free entries
> are not being reclaimed). Seems like this could use a huge amount of memory.
> Yes, 51 MB is not that much, but suppose there are a bunch of consumers and
> hence a ConsumerMessageRef for each one. (Maybe I'm missing something....)
> Perhaps this linked list could be pushed into the Kaha store itself, by
> rewriting the IndexItems on disk to point previous/next free item, thus
> maintaining this on disk and in place. For perf reasons, maybe supplement
> with some caching but that might not really be necessary because the OS cache
> should help out.
> A lot of the other places in Kaha (such as ListContainerImpl.java) have
> caches which limit to say 100 cached items, but the free list seems to
> obviate all of that stuff due to it being essentially unbounded.
> Any thoughts?
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