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Posted to issues@hbase.apache.org by "Lars Hofhansl (JIRA)" <ji...@apache.org> on 2016/07/18 09:10:20 UTC
[jira] [Commented] (HBASE-15453) [Performance] Considering
reverting HBASE-10015 - reinstate synchronized in StoreScanner
[ https://issues.apache.org/jira/browse/HBASE-15453?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15381946#comment-15381946 ]
Lars Hofhansl commented on HBASE-15453:
---------------------------------------
Alright shall I commit to all branches (except trunk, which removed the synchronization)?
> [Performance] Considering reverting HBASE-10015 - reinstate 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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