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https://issues.apache.org/jira/browse/CASSANDRA-6488?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Aleksey Yeschenko updated CASSANDRA-6488:
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Attachment: 6488-fix.txt
Separates TM.cloneOnlyTokenMap() and TM.cachedOnlyTokenMap() and only switched
SP.getBatchlogEndpoints() and ARS.getNaturalEndpoints() to use the cached
version.
They aren't the only methods that *don't* mutate the returned metadata, but
going through the rest of the usages and optimizing those can wait.
Also fixes a regression from 6435 in TM.cachedOnlyTokenMap().
> Batchlog writes consume unnecessarily large amounts of CPU on vnodes clusters
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-6488
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6488
> Project: Cassandra
> Issue Type: Bug
> Reporter: Rick Branson
> Assignee: Rick Branson
> Fix For: 1.2.13, 2.0.4
>
> Attachments: 6488-fix.txt, 6488-rbranson-patch.txt, 6488-v2.txt,
> 6488-v3.txt, graph (21).png
>
>
> The cloneTokenOnlyMap call in StorageProxy.getBatchlogEndpoints causes
> enormous amounts of CPU to be consumed on clusters with many vnodes. I
> created a patch to cache this data as a workaround and deployed it to a
> production cluster with 15,000 tokens. CPU consumption drop to 1/5th. This
> highlights the overall issues with cloneOnlyTokenMap() calls on vnodes
> clusters. I'm including the maybe-not-the-best-quality workaround patch to
> use as a reference, but cloneOnlyTokenMap is a systemic issue and every place
> it's called should probably be investigated.
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