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From "ASF GitHub Bot (JIRA)" <>
Subject [jira] [Commented] (ACCUMULO-4187) Rate limiting of major compactions
Date Mon, 18 Apr 2016 15:08:25 GMT


ASF GitHub Bot commented on ACCUMULO-4187:

Github user joshelser commented on the pull request:
    >  I suppose the test would make sure a compaction doesn't run too fast?
    Yeah, I was thinking about how best to test this. You can only reasonably assert a lower-bound
on compaction time (to avoid performance skew on certain hosts). Maybe turning off compression
for a table, writing a bunch of data and then asserting that a compaction takes at least X
time is easiest. You'll still have to account for "compression" from the run-length encoding,
but at least that should be uniform across hosts.

> 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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