[jira] [Commented] (OAK-6915) Minimize the amount of uncached segment reads

[Andrei Dulceanu (JIRA)]

    [ 
https://issues.apache.org/jira/browse/OAK-6915?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16243947#comment-16243947
 ] 

Andrei Dulceanu commented on OAK-6915:
--------------------------------------

And here's the data about allocations/reads (available only for Oak 
1.8-SNAPSHOT *with patch*):
|Oak-Segment-Tar |{noformat}
13:50:42.583 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK segment ID 
allocations: 50681
13:50:42.583 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK uncached 
segment reads: 0
{noformat}|
|Oak-Segment-Tar-DS|{noformat}
15:37:24.332 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK segment ID 
allocations: 43
15:37:24.332 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK uncached 
segment reads: 0
{noformat}|
|Oak-Segment-Tar-Cold(Shared DS)|{noformat}
5:39:17.769 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK closed: 
target/Oak-Segment-Tar-Cold-1510148289056/primary-0
15:39:17.769 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK segment ID 
allocations: 72
15:39:17.769 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK uncached 
segment reads: 13
15:39:17.844 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK closed: 
target/Oak-Segment-Tar-Cold-1510148289056/standby-0
15:39:17.844 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK segment ID 
allocations: 72
15:39:17.844 [main] INFO  o.a.j.oak.segment.file.FileStore - TarMK uncached 
segment reads: 13
{noformat}|


> Minimize the amount of uncached segment reads
> ---------------------------------------------
>
>                 Key: OAK-6915
>                 URL: https://issues.apache.org/jira/browse/OAK-6915
>             Project: Jackrabbit Oak
>          Issue Type: Improvement
>          Components: segment-tar
>            Reporter: Francesco Mari
>            Assignee: Francesco Mari
>             Fix For: 1.8, 1.7.12
>
>         Attachments: OAK-6915-01.patch, OAK-6915-02.patch, 
> OAK-6915-diagnostics.patch
>
>
> The current implementation of {{SegmentCache}} should make better use of the 
> underlying Guava cache by relying on the cached segments instead of 
> unconditionally performing an uncached segment read via the 
> {{Callable<Segment>}} passed to {{SegmentCache#getSegment}}.



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