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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-4187) Rate limiting of major compactions
Date Thu, 14 Apr 2016 18:29:25 GMT


ASF GitHub Bot commented on ACCUMULO-4187:

Github user ShawnWalker commented on the pull request:
    I've made changes to address most of the comments on this thread.  I've also addressed
a performance concern that Keith Turner noticed (`PositionedOutputs.PositionedOutputStream`
was behaving poorly).
    I've additionally fixed an issue with tracing in `TabletServerBatchWriter` that was causing
the test `ShellServerIT.trace(...)` to fail for me for reasons unrelated to my changes.  Perhaps
I should separate that out as a separate issue/patch?

> Rate limiting of major compactions
> ----------------------------------
>                 Key: ACCUMULO-4187
>                 URL:
>             Project: Accumulo
>          Issue Type: Improvement
>          Components: core, tserver
>            Reporter: Shawn Walker
>            Assignee: Shawn Walker
>            Priority: Minor
>             Fix For: 1.8.0
> In discussing [ACCUMULO-4166] with Keith Turner, we decided that the underlying issue
is that major compactions can overwhelm a tablet server, rendering it nearly unresponsive.
> To address this, we should take a cue from Apache Cassandra and restrict how quickly
we perform major compactions.  Rate limiting reads and writes involved in major compactions
will directly affect the IO load caused by major compactions, and should also indirectly affect
the CPU load.

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