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https://issues.apache.org/jira/browse/HBASE-7868?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13580702#comment-13580702
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Lars Hofhansl commented on HBASE-7868:
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JM, what I am saying is that
{{bin/hbase org.apache.hadoop.hbase.PerformanceEvaluation --rows=100000
filterScan 1}}
opens 100000 scanners and calls next until there are no more rows. That would
"never" finish unless your each scan returns almost no data. You are not
testing scan performance with that, but RPC/Network performance (if you're
testing locally you're testing context switch performance through the lo
interface).
Do you seed the table with by calling SequentialWriteTest before running each
read test?
(I find that I have to do that, and otherwise there is just an empty test table)
The performance improvement after 0.94.0 that I measure this way is in line
with other tests I did before.
> HFile performance regression between 0.92 and 0.94
> --------------------------------------------------
>
> Key: HBASE-7868
> URL: https://issues.apache.org/jira/browse/HBASE-7868
> Project: HBase
> Issue Type: Bug
> Components: io
> Affects Versions: 0.94.5
> Reporter: Matteo Bertozzi
> Assignee: Matteo Bertozzi
> Fix For: 0.94.6
>
> Attachments: FilteredScan.png, hfileperf-graphs.png,
> performances.pdf, performances.pdf
>
>
> By HFilePerformanceEvaluation seems that 0.94 is slower then 0.92
> Looking at the profiler for the Scan path, seems that most of the time,
> compared to 92, is spent in the metrics dictionary lookup. [~eclark] pointed
> out the new per family/block metrics.
> By commenting the metrics call in HFileReaderV2, the performance seems to get
> better, but maybe metrics is not the only problem.
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