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https://issues.apache.org/jira/browse/OAK-4015?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael Dürig updated OAK-4015:
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Attachment: OAK-4015.m
OAK-4015.pdf
Running the {{SegmentCompactionIT}} for a couple of dozen cycles against above
fix and comparing the times it takes for the individual compaction cycles shows
a (very) slight improvement. See [^OAK-4015.pdf]. As there is no regression,
the fix is simple and might show better numbers for other cases, I will go
forward with this.
[^OAK-4015.m] contains the raw data and a Matlab script for creating the
presented figures.
> Expedite commits from the compactor
> -----------------------------------
>
> Key: OAK-4015
> URL: https://issues.apache.org/jira/browse/OAK-4015
> Project: Jackrabbit Oak
> Issue Type: Improvement
> Components: segment-tar
> Reporter: Michael Dürig
> Assignee: Michael Dürig
> Labels: compaction, gc, perfomance
> Fix For: Segment Tar 0.0.12
>
> Attachments: OAK-4015-histo.png, OAK-4015-wait-time.png, OAK-4015.m,
> OAK-4015.pdf
>
>
> Concurrent commits during compaction cause those to be re-compacted.
> Currently it seems that the compaction thread can end up waiting for some
> time to acquire the commit lock [1], which in turn causes more commits to
> pile up to be re-compacted. I think this could be improved by tweaking the
> lock such that the compactor could jump ahead of the queue. I.e. use a lock
> which can be acquired in expedited mode.
> [1] SegmentNodeStore#commitSemaphore
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