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https://issues.apache.org/jira/browse/OAK-1926?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Chetan Mehrotra updated OAK-1926:
---------------------------------
Fix Version/s: 1.0.4
> UnmergedBranch state growing with empty BranchCommit leading to performance
> degradation
> ---------------------------------------------------------------------------------------
>
> Key: OAK-1926
> URL: https://issues.apache.org/jira/browse/OAK-1926
> Project: Jackrabbit Oak
> Issue Type: Bug
> Components: mongomk
> Affects Versions: 1.0.1
> Reporter: Chetan Mehrotra
> Assignee: Chetan Mehrotra
> Fix For: 1.1, 1.0.4
>
> Attachments: OAK-1926.patch
>
>
> In some cluster deployment cases it has been seen that in memory state of
> UnmergedBranches contains large number of empty commits. For e.g. in one of
> of the runs there were 750 entries in the UnmergedBranches and each Branch
> had empty branch commits.
> If there are large number of UnmergedBranches then read performance would
> degrade as for determining revision validity currently logic scans all
> branches
> Below is some part of UnmergedBranch state
> {noformat}
> Branch 1
> 1 -> br146d2edb7a7-0-1 (true) (revision: "br146d2edb7a7-0-1", clusterId: 1,
> time: "2014-06-25 05:08:52.903", branch: true)
> 2 -> br146d2f0450b-0-1 (true) (revision: "br146d2f0450b-0-1", clusterId: 1,
> time: "2014-06-25 05:11:40.171", branch: true)
> Branch 2
> 1 -> br146d2ef1d08-0-1 (true) (revision: "br146d2ef1d08-0-1", clusterId: 1,
> time: "2014-06-25 05:10:24.392", branch: true)
> Branch 3
> 1 -> br146d2ed26ca-0-1 (true) (revision: "br146d2ed26ca-0-1", clusterId: 1,
> time: "2014-06-25 05:08:15.818", branch: true)
> 2 -> br146d2edfd0e-0-1 (true) (revision: "br146d2edfd0e-0-1", clusterId: 1,
> time: "2014-06-25 05:09:10.670", branch: true)
> Branch 4
> 1 -> br146d2ecd85b-0-1 (true) (revision: "br146d2ecd85b-0-1", clusterId: 1,
> time: "2014-06-25 05:07:55.739", branch: true)
> Branch 5
> 1 -> br146d2ec21a0-0-1 (true) (revision: "br146d2ec21a0-0-1", clusterId: 1,
> time: "2014-06-25 05:07:08.960", branch: true)
> 2 -> br146d2ec8eca-0-1 (true) (revision: "br146d2ec8eca-0-1", clusterId: 1,
> time: "2014-06-25 05:07:36.906", branch: true)
> Branch 6
> 1 -> br146d2eaf159-1-1 (true) (revision: "br146d2eaf159-1-1", clusterId: 1,
> time: "2014-06-25 05:05:51.065", counter: 1, branch: true)
> Branch 7
> 1 -> br146d2e9a513-0-1 (true) (revision: "br146d2e9a513-0-1", clusterId: 1,
> time: "2014-06-25 05:04:26.003", branch: true)
> {noformat}
> [~mreutegg] Suggested that these branch might be for those revision which
> have resulted in a collision and upon checking it indeed appears to be the
> case (value true in brackets above indicate that). Further given the age of
> such revision it looks like they get populated upon startup itself
> *Fix*
> * Need to check why we need to populate the UnermgedBranch
> * Possibly implement some purge job which would remove such stale entries
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