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https://issues.apache.org/jira/browse/CASSANDRA-5220?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13971574#comment-13971574
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Ryan McGuire edited comment on CASSANDRA-5220 at 4/16/14 4:05 PM:
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This is a yourkit comparison between the two runs of the dtest. Old Time is
without vnodes, New Time is with vnodes. I turned off internode_compression
because that run showed all the time being spent in Snappy compressor code, but
even without compression the repair time didn't improve (much):
!5220-yourkit.png!
was (Author: enigmacurry):
I don't have a lot of experience with java profiling, but this is a yourkit
comparison between the two runs of the dtest. Old Time is without vnodes, New
Time is with vnodes. I turned off internode_compression because that run showed
all the time being spent in Snappy compressor code, but even without
compression the repair time didn't improve (much):
!5220-yourkit.png!
> Repair improvements when using vnodes
> -------------------------------------
>
> Key: CASSANDRA-5220
> URL: https://issues.apache.org/jira/browse/CASSANDRA-5220
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Affects Versions: 1.2.0 beta 1
> Reporter: Brandon Williams
> Assignee: Yuki Morishita
> Labels: performance, repair
> Fix For: 2.1 beta2
>
> Attachments: 5220-yourkit.png, 5220-yourkit.tar.bz2
>
>
> Currently when using vnodes, repair takes much longer to complete than
> without them. This appears at least in part because it's using a session per
> range and processing them sequentially. This generates a lot of log spam
> with vnodes, and while being gentler and lighter on hard disk deployments,
> ssd-based deployments would often prefer that repair be as fast as possible.
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