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From "ramkrishna.s.vasudevan (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-13291) Lift the scan ceiling
Date Mon, 23 Mar 2015 05:25:11 GMT

    [ https://issues.apache.org/jira/browse/HBASE-13291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14375418#comment-14375418
] 

ramkrishna.s.vasudevan commented on HBASE-13291:
------------------------------------------------

One thing I would like to say here is that when I tried profiling with jprofiler the impact
on the CPU with filterAll and without Filterall was varying betwee 5 to 8%.  But every time
with filterall it is was taking more CPU but not in the order of 3X.

> Lift the scan ceiling
> ---------------------
>
>                 Key: HBASE-13291
>                 URL: https://issues.apache.org/jira/browse/HBASE-13291
>             Project: HBase
>          Issue Type: Improvement
>          Components: Scanners
>    Affects Versions: 1.0.0
>            Reporter: stack
>            Assignee: stack
>         Attachments: 13291.inlining.txt, q (1).png, traces.7.svg, traces.filterall.svg,
traces.nofilter.svg, traces.smaller.svg
>
>
> Scanning medium sized rows with multiple concurrent scanners exhibits interesting 'ceiling'
properties. A server runs at about 6.7k ops a second using 450% of possible 1600% of CPUs
 when 4 clients each with 10 threads doing scan 1000 rows.  If I add '--filterAll' argument
(do not return results), then we run at 1450% of possible 1600% possible but we do 8k ops
a second.
> Let me attach flame graphs for two cases. Unfortunately, there is some frustrating dark
art going on. Let me try figure it... Filing issue in meantime to keep score in.



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