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Posted to issues@hbase.apache.org by "stack (JIRA)" <ji...@apache.org> on 2016/03/14 20:52:33 UTC

[jira] [Updated] (HBASE-15453) [Performance] Considering reverting HBASE-10015 - reinstance synchronized in StoreScanner

     [ https://issues.apache.org/jira/browse/HBASE-15453?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

stack updated HBASE-15453:
--------------------------
       Assignee: Lars Hofhansl
       Priority: Critical  (was: Major)
    Component/s: Performance
     Issue Type: Improvement  (was: Bug)
        Summary: [Performance] Considering reverting HBASE-10015 - reinstance synchronized in StoreScanner  (was: Considering reverting HBASE-10015 - reinstance synchronized in StoreScanner)

Marking Critical because seems like big benefit for simple change. I can try this later....

> [Performance] Considering reverting HBASE-10015 - reinstance synchronized in StoreScanner
> -----------------------------------------------------------------------------------------
>
>                 Key: HBASE-15453
>                 URL: https://issues.apache.org/jira/browse/HBASE-15453
>             Project: HBase
>          Issue Type: Improvement
>          Components: Performance
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>            Priority: Critical
>         Attachments: 15453-0.98.txt
>
>
> In HBASE-10015 back then I found that intrinsic locks (synchronized) in StoreScanner are slower that explicit locks.
> I was surprised by this. To make sure I added a simple perf test and many folks ran it on their machines. All found that explicit locks were faster.
> Now... I just ran that test again. On the latest JDK8 I find that now the intrinsic locks are significantly faster:
> (OpenJDK Runtime Environment (build 1.8.0_72-b15))
> Explicit locks:
> 10 runs  mean:2223.6 sigma:72.29412147609237
> Intrinsic locks:
> 10 runs  mean:1865.3 sigma:32.63755505548784
> I confirmed the same with timing some Phoenix scans. We can save a bunch of time by changing this back 
> Arrghhh... So maybe it's time to revert this now...?
> (Note that in trunk due to [~ram_krish]'s work, we do not lock in StoreScanner anymore)
> I'll attach the perf test and a patch that changes lock to synchronized, if some folks could run this on 0.98, that'd be great.



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