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From "Peter Schuller (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3668) Performance of sstableloader is affected in 1.0.x
Date Fri, 27 Jan 2012 08:57:48 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3668?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13194562#comment-13194562
] 

Peter Schuller commented on CASSANDRA-3668:
-------------------------------------------

Ok. Definitely interesting to look into then, because just the fact that we're copying some
arrays around is not adequate explanation for how we would bottleneck to the point of only
reaching 7 MB/second (that's *nothing*). The indexes/bloom filters sound more plausible, but
my understanding was that Manish never observed CPU saturation.

Anyways, I was asking since I was assigned to review the patch. I'll try to do a comparison
of my own and see what I can find out.

*Possibly* relatedly I have observed cases where there is clearly something wrong with the
way we do I/O. Index sampling on start-up have been observed at 20% CPU utilization with plenty
of I/O capacity to spare (this is on 0.8 though). In this case something is clearly outright
wrong, and is not about performance bottlenecks as such. It's possible something similar is
going on here, which would be very interesting to confirm/deny.
                
> Performance of sstableloader is affected in 1.0.x
> -------------------------------------------------
>
>                 Key: CASSANDRA-3668
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3668
>             Project: Cassandra
>          Issue Type: Bug
>          Components: API
>    Affects Versions: 1.0.0
>            Reporter: Manish Zope
>            Assignee: Yuki Morishita
>            Priority: Minor
>              Labels: streaming
>             Fix For: 1.1
>
>         Attachments: 0001-Allow-multiple-connection-in-StreamInSession.patch, 0002-Allow-concurrent-stream-in-StreamOutSession.patch,
0003-Add-threads-option-to-sstableloader.patch, 3688-reply_before_closing_writer.txt, sstable-loader
performance.txt
>
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> One of my colleague had reported the bug regarding the degraded performance of the sstable
generator and sstable loader.
> ISSUE :- https://issues.apache.org/jira/browse/CASSANDRA-3589 
> As stated in above issue generator performance is rectified but performance of the sstableloader
is still an issue.
> 3589 is marked as duplicate of 3618.Both issues shows resolved status.But the problem
with sstableloader still exists.
> So opening other issue so that sstbleloader problem should not go unnoticed.
> FYI : We have tested the generator part with the patch given in 3589.Its Working fine.
> Please let us know if you guys require further inputs from our side.

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