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Posted to oak-issues@jackrabbit.apache.org by "Michael Dürig (JIRA)" <ji...@apache.org> on 2017/12/06 10:13:00 UTC
[jira] [Resolved] (OAK-6255) Minor performance impact by collecting
data for SegmentCache statistics
[ https://issues.apache.org/jira/browse/OAK-6255?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Michael Dürig resolved OAK-6255.
--------------------------------
Resolution: Not A Problem
Fix Version/s: (was: 1.8)
Resolving as not a problem since so far we didn't see an impact of this.
> Minor performance impact by collecting data for SegmentCache statistics
> ------------------------------------------------------------------------
>
> Key: OAK-6255
> URL: https://issues.apache.org/jira/browse/OAK-6255
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: segment-tar
> Reporter: Michael Dürig
> Assignee: Michael Dürig
> Priority: Minor
> Labels: perfomance
>
> OAK-5956 improved the statistics collected for the segment cache. As I expected this had an impact on performance as measured by our micro benchmarks. An impact is visible for {{ConcurrentReadTest}}, {{ConcurrentReadWriteTest}} and {{ConcurrentWriteTest}}. Impact on full stack operation is yet to be determined (I assume it is neglectable though).
> {noformat}
> # ConcurrentReadTest C min 10% 50% 90% max N
> Oak-Segment-Tar (base) 1 43 101 112 129 219 525
> Oak-Segment-Tar (OAK-5956) 1 45 104 118 138 264 496
> {noformat}
> The impact seems to be mostly caused by the {{SegmentId.onAccess}} callback.
> Possible solutions:
> * Replace the {{SegmentId.onAccess}} callback with a direct reference to the underlying counter.
> * Allow disabling of the cache statistics.
> * Do nothing and accept the performance impact.
> The first approach is least attractive as it breaks encapsulation. Depending on the impact of this on full stack operations I'd either go with the 2nd or 3rd option.
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