[jira] [Comment Edited] (OAK-2849) Improve revision gc on SegmentMK

["Alex Parvulescu (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/OAK-2849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14716817#comment-14716817 ] 

Alex Parvulescu edited comment on OAK-2849 at 8/27/15 3:21 PM:
---------------------------------------------------------------

I noticed something today related to the SegmentCompactionIT test. I left it running a bit with 4 writers then I opened it in the Explorer :)

It looks like 1Gb out of the total 4Gb reported size (7.5Gb on disk actually) is the _:conflict_ node on root. but it looks like many of the nodes have such a conflict node. [~mduerig] any ideas?

More on conflicts. I see the following structures, which look off to me (2 or even 3 _:conflict_ nodes on top of each other)
{code}
/root/NW1611/:conflict/deleteDeletedNode/:conflict/deleteChangedNode/NW2379 
{code}
or even
{code}
/root/NW1611/:conflict/deleteChangedNode/NW2555/:conflict/changeDeletedNode/NW4793/NW0550/:conflict
{code}



was (Author: alex.parvulescu):
I noticed something today related to the SegmentCompactionIT test. I left it running a bit with 4 writers then I opened it in the Explorer :)

It looks like 1Gb out of the total 4Gb reported size (7.5Gb on disk actually) is the _:conflict_ node on root. but it looks like many of the nodes have such a conflict node. [~mduerig] any ideas?

> Improve revision gc on SegmentMK
> --------------------------------
>
>                 Key: OAK-2849
>                 URL: https://issues.apache.org/jira/browse/OAK-2849
>             Project: Jackrabbit Oak
>          Issue Type: Task
>          Components: segmentmk
>            Reporter: Michael Dürig
>            Assignee: Michael Dürig
>              Labels: compaction, gc
>             Fix For: 1.3.6
>
>         Attachments: SegmentCompactionIT-conflicts.png
>
>
> This is a container issue for the ongoing effort to improve revision gc of the SegmentMK. 
> I'm exploring 
> * ways to make the reference graph as exact as possible and necessary: it should not contain segments that are not referenceable any more and but must contain all segments that are referenceable. 
> * ways to segregate the reference graph reducing dependencies between certain set of segments as much as possible. 
> * Reducing the number of in memory references and their impact on gc as much as possible.
> Work in progress is in my private [Github fork|https://github.com/mduerig/jackrabbit-oak]. As soon as something is promising enough to make it into Oak, I spawn of an issue an make it a subtask of this task. 



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