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From "Jonathan Ellis (JIRA)" <>
Subject [jira] [Commented] (CASSANDRA-6142) Remove multithreaded compaction
Date Thu, 03 Oct 2013 22:38:41 GMT


Jonathan Ellis commented on CASSANDRA-6142:

Pushed removal to

Also removes PrecompactedRow, which is no longer necessary, and fixes a couple existing bugs
in LCR and Scrub that this revealed (last two commits).

> Remove multithreaded compaction
> -------------------------------
>                 Key: CASSANDRA-6142
>                 URL:
>             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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