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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2014/06/23 17:45:27 UTC

[jira] [Updated] (CASSANDRA-6142) Remove multithreaded compaction (and precompactedrow)

     [ https://issues.apache.org/jira/browse/CASSANDRA-6142?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis updated CASSANDRA-6142:
--------------------------------------

    Summary: Remove multithreaded compaction (and precompactedrow)  (was: Remove multithreaded compaction)

> Remove multithreaded compaction (and precompactedrow)
> -----------------------------------------------------
>
>                 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 beta1
>
>
> 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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