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https://issues.apache.org/jira/browse/HBASE-14205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14682302#comment-14682302
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Andrew Purtell commented on HBASE-14205:
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On HBASE-13420 the suggestion (from John Leach) was remove entirely. I agree
with that approach, but Srikanth and I both thought that would amount to a
functional regression if done in a patch release. Yeah, the 'function' is a
performance concern. The remainder of the issue focused on mitigating John's
issue. We could also turn it off with a config toggle I suppose and see if
someone complains about a functional regression. In any case, why not just
remove this entirely from 1.2 and up?
> RegionCoprocessorHost System.nanoTime() performance bottleneck
> --------------------------------------------------------------
>
> Key: HBASE-14205
> URL: https://issues.apache.org/jira/browse/HBASE-14205
> Project: HBase
> Issue Type: Bug
> Reporter: Jan Van Besien
> Priority: Critical
> Fix For: 2.0.0, 1.2.0, 1.3.0
>
>
> 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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