[
https://issues.apache.org/jira/browse/HBASE-13291?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14384273#comment-14384273
]
Lars Hofhansl commented on HBASE-13291:
---------------------------------------
Ah. Hence the seeking. In that case the optimize won't help, but also still
won't do any work for those (it's only does anything for SEEK_NEXT_COL and
SEEK_NEXT_ROW).
But since you see optimize being called and doing some work there must be many
COL or ROW seeks, and I'd expect it to be worse without HBASE-13109 applied,
then again with large cells there won't be much advantage to skipping a lot
before we'd hit the next block (at most 64 cells would fit into a 64k block)...
Would be cool to know what perf you'd see without HBASE-13109.
Is this a common usecase? We'd have essentially an HFile block per row here,
right?
I'll also test with wider rows for this issue... Very curious about this!
> 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, Screen Shot 2015-03-26 at 12.12.13
> PM.png, Screen Shot 2015-03-26 at 3.39.33 PM.png, hack_to_bypass_bb.txt,
> nonBBposAndInineMvccVint.txt, q (1).png, traces.7.svg, traces.filterall.svg,
> traces.nofilter.svg, traces.small2.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.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
