[jira] [Commented] (HBASE-14205) RegionCoprocessorHost System.nanoTime() performance bottleneck

["Steen Manniche (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-14205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15842877#comment-15842877 ] 

Steen Manniche commented on HBASE-14205:
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The official HBase documentation still lists this functionality as available, which cost me some time looking through configuration files before I found this issue. The part in question is this:
http://hbase.apache.org/book.html#_monitor_time_spent_in_coprocessors

> RegionCoprocessorHost System.nanoTime() performance bottleneck
> --------------------------------------------------------------
>
>                 Key: HBASE-14205
>                 URL: https://issues.apache.org/jira/browse/HBASE-14205
>             Project: HBase
>          Issue Type: Bug
>          Components: Coprocessors, Performance, regionserver
>            Reporter: Jan Van Besien
>            Assignee: Andrew Purtell
>            Priority: Critical
>              Labels: needs_releasenote
>             Fix For: 2.0.0, 1.2.0, 1.3.0
>
>         Attachments: HBASE-14205.patch
>
>
> The tracking of execution time of coprocessor methods introduced in HBASE-11516 introduces 2 calls to System.nanoTime() per coprocessor method per coprocessor. This is resulting in a serious performance bottleneck in certain scenarios.
> For example consider the scenario where many rows are being ingested (PUT) in a table which has multiple coprocessors (we have up to 20 coprocessors). This results in 8 extra calls to System.nanoTime() per coprocessor (prePut, postPut, postStartRegionOperation and postCloseRegionOperation) which has in total (i.e. times 20) been seen to result in a 50% increase of execution time.
> I think it is generally considered bad practice to measure execution times on such a small scale (per single operation). Also note that measurements are taken even for coprocessors that do not even have an actual implementation for certain operations, making the problem worse.



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