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Posted to issues@hbase.apache.org by "Elliott Clark (JIRA)" <ji...@apache.org> on 2012/08/17 02:21:37 UTC
[jira] [Commented] (HBASE-6603)
RegionMetricsStorage.incrNumericMetric is called too often
[ https://issues.apache.org/jira/browse/HBASE-6603?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13436465#comment-13436465 ]
Elliott Clark commented on HBASE-6603:
--------------------------------------
wow that's a huge perf gain.
Thanks.
> RegionMetricsStorage.incrNumericMetric is called too often
> ----------------------------------------------------------
>
> Key: HBASE-6603
> URL: https://issues.apache.org/jira/browse/HBASE-6603
> Project: HBase
> Issue Type: Bug
> Components: performance
> Reporter: Lars Hofhansl
> Assignee: Lars Hofhansl
> Fix For: 0.96.0, 0.94.2
>
>
> Running an HBase scan load through the profiler revealed that RegionMetricsStorage.incrNumericMetric is called way too often.
> It turns out that we make this call for *each* KV in StoreScanner.next(...).
> Incrementing AtomicLong requires expensive memory barriers.
> The observation here is that StoreScanner.next(...) can maintain a simple
> long in its internal loop and only update the metric upon exit. Thus the AtomicLong is not updated nearly as often.
> That cuts about 10% runtime from scan only load (I'll quantify this better soon).
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