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https://issues.apache.org/jira/browse/OAK-3177?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14659948#comment-14659948
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Michael Dürig edited comment on OAK-3177 at 8/6/15 12:40 PM:
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[^OAK-3177.png]
Attaching a graph showing average compaction times with and without the patch
for 7 subsequent compaction cycles on a repository with 5 concurrent writer
threads ({{SegmentCompactionIT}}). The graphs show the times of the individual
compaction cycles normalised against the first cycle.
was (Author: mduerig):
!OAK-3177.png!
Attaching a graph showing average compaction times with and without the patch
for 7 subsequent compaction cycles on a repository with 5 concurrent writer
threads ({{SegmentCompactionIT}}). The graphs show the times of the individual
compaction cycles normalised against the first cycle.
> Compaction slow on repository with continuous writes
> ----------------------------------------------------
>
> Key: OAK-3177
> URL: https://issues.apache.org/jira/browse/OAK-3177
> Project: Jackrabbit Oak
> Issue Type: Sub-task
> Components: segmentmk
> Reporter: Michael Dürig
> Assignee: Michael Dürig
> Labels: compaction, gc
> Fix For: 1.3.5
>
> Attachments: OAK-3177.patch, OAK-3177.png
>
>
> OAK-2734 introduced retry cycles and the option to force compaction when all
> cycles fail. However OAK-2192 introduced a performance regression: each
> compaction cycle takes in the order of the size of the repository to complete
> instead of in the order of the number of remaining changes to compact. This
> is caused by comparing compacted with pre-compacted node states, which is
> necessary to avoid mixed segments (aka OAK-2192). To fix the performance
> regression I propose to pass the compactor an additional node state (the
> 'onto' state). The diff would then be calculated across the pre compacted
> states, which performs in the order of number of changes. The changes would
> then be applied to the 'onto' state, which is a compacted state to avoid
> mixed segments.
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