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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-12366) Fix compaction throttle
Date Wed, 03 Aug 2016 16:34:20 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-12366?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15406166#comment-15406166
] 

T Jake Luciani commented on CASSANDRA-12366:
--------------------------------------------

I pushed an update to fix the compression ratio calc. Also, I noticed the way of calculating
the size read was broken for leveled compactions since we combine many sstables into the scanner.
 When a reader jumps from one sstable to another there may be big jumps which don't reflect
the actual read amount.

I also added this to cleanup, verify, gc compactions. 

> Fix compaction throttle
> -----------------------
>
>                 Key: CASSANDRA-12366
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-12366
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Compaction
>            Reporter: T Jake Luciani
>            Assignee: T Jake Luciani
>             Fix For: 3.x
>
>
> Compaction throttling is broken in the following ways:
>   * It throttles bytes read after being decompressed
>   * Compaction creates multiple scanners which share the rate limiter causing too much
throttling
>   * It bears no resemblance to the reported compaction time remaining calculation (Bytes
of source sstables processed since start of compaction)
> To fix this we need to simplify the throttling to be only at the CompactionIterator level.



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