[jira] [Created] (CASSANDRA-6488) Batchlog writes consume unnecessarily large amounts of CPU on vnodes clusters

["Rick Branson (JIRA)" <ji...@apache.org>]

Rick Branson created CASSANDRA-6488:
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             Summary: 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: Aleksey Yeschenko
         Attachments: 6488-rbranson-patch.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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