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https://issues.apache.org/jira/browse/CASSANDRA-6142?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13801998#comment-13801998
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Jonathan Ellis commented on CASSANDRA-6142:
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I'm guessing not super common because the existing code will just break if it
hits that case. (A LCR object will throw errors if you try to use it after
advancing the underlying stream to another row.)
I guess the next step is probably for me to pull the fixes out for application
to 2.0.
> Remove multithreaded compaction
> -------------------------------
>
> Key: CASSANDRA-6142
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6142
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Jonathan Ellis
> Assignee: Jonathan Ellis
> Priority: Minor
> Fix For: 2.1
>
>
> There is at best a very small sweet spot for multithreaded compaction
> (ParallelCompactionIterable). For large rows, we stall the pipeline and fall
> back to a single LCR pass. For small rows, the overhead of the coordination
> outweighs the benefits of parallelization (45s to compact 2x1M stress rows
> with multithreading enabled, vs 35 with it disabled).
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