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https://issues.apache.org/jira/browse/CASSANDRA-14475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16493474#comment-16493474
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Thomas Steinmaurer commented on CASSANDRA-14475:
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[~jasobrown], thanks! Sorry for being a pain, but any chance to get this
back-ported for 2.1+?
> nodetool - Occasional high CPU on large, CPU capable machines
> -------------------------------------------------------------
>
> Key: CASSANDRA-14475
> URL: https://issues.apache.org/jira/browse/CASSANDRA-14475
> Project: Cassandra
> Issue Type: Bug
> Components: Tools
> Reporter: Thomas Steinmaurer
> Assignee: Thomas Steinmaurer
> Priority: Major
> Fix For: 4.0, 3.11.3
>
> Attachments: nodetool_gc_threads.patch,
> nodetool_highcpu_gcthreads1_cassandra_JIRA.png
>
>
> Periodically calling nodetool every 5 min results in increased CPU usage by
> nodetool only on a machine with 32 physical cores (64 vCPUs) according to our
> monitoring:
> !nodetool_highcpu_gcthreads1_cassandra_JIRA.png|width=600!
> Investigation and testing has shown that it is related to running with
> default number of parallel GC threads which is 43 on this particular machine.
> We see a System.gc() according to flight recorder but no real evidence from
> where it comes from. The nodetool call in question is simply gathering e.g.
> the version with "nodetool version".
> After explicitly setting the number of parallel GC threads to 1, the high CPU
> is entirely gone (see chart above), without impacting nodetool being executed
> successfully. 1 parallel GC thread should be sufficient for nodetool anyway I
> think.
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