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From Michael Dürig (JIRA) <j...@apache.org>
Subject [jira] [Comment Edited] (OAK-4293) Refactor / rework compaction gain estimation
Date Tue, 09 Aug 2016 12:35:20 GMT

    [ https://issues.apache.org/jira/browse/OAK-4293?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15413449#comment-15413449
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Michael Dürig edited comment on OAK-4293 at 8/9/16 12:35 PM:
-------------------------------------------------------------

I think the simplest solution would be to call {{GCJournal.persist()}} directly from {{FileStore#cleanup(Predicate<Integer>,
String)}} instead of looping it through {{GCMonitor.cleaned()}}. This way there is no registering
needed. 

OTOH, I'm not too happy with the record id in the gc journal as its semantics seem vague to
me. Maybe replace it with the record id that resulted from compaction!?



was (Author: mduerig):
I think the simplest solution would be to call {{GCJournal.persist()}} directly from {{FileStore#cleanup(Predicate<Integer>,
String)}} instead of looping it through {{GCMonitor.cleaned()}}. This way there is no registering
needed. 

OTOH, I'm not too happy with the record id in the gc journal as its semantics seem vague to
me. Or better replace it with the record id that resulted from compaction. 


> Refactor / rework compaction gain estimation 
> ---------------------------------------------
>
>                 Key: OAK-4293
>                 URL: https://issues.apache.org/jira/browse/OAK-4293
>             Project: Jackrabbit Oak
>          Issue Type: Task
>          Components: segment-tar
>            Reporter: Michael Dürig
>            Assignee: Alex Parvulescu
>              Labels: gc
>             Fix For: Segment Tar 0.0.10
>
>         Attachments: OAK-4293-v2.patch, size-estimation.patch
>
>
> I think we have to take another look at {{CompactionGainEstimate}} and see whether we
can up with a more efficient way to estimate the compaction gain. The current implementation
is expensive wrt. IO, CPU and cache coherence. If we want to keep an estimation step we need
IMO come up with a cheap way (at least 2 orders of magnitude cheaper than compaction). Otherwise
I would actually propose to remove the current estimation approach entirely 



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