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From "Thomas Mueller (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (OAK-3007) SegmentStore cache does not take "string" map into account
Date Thu, 09 Jul 2015 12:15:04 GMT

    [ https://issues.apache.org/jira/browse/OAK-3007?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14620405#comment-14620405
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Thomas Mueller commented on OAK-3007:
-------------------------------------

For future reference, a benchmark I ran was:

{noformat}
java -Dwarmup=5 -Druntime=2 -Dprofile=true -jar target/oak-run-1.4-SNAPSHOT.jar 
    benchmark ReadPropertyTest Oak-Tar | grep "Segment.read"
{noformat}

This does not show readString, but many readTemplate calls. Possibly the following tests could
be run as well:


ReadDeepTreeTest
ConcurrentReadDeepTreeTest
ConcurrentReadRandomNodeAndItsPropertiesTest
ConcurrentReadTest
ConcurrentTraversalTest
DescendantSearchTest
GetDeepNodeTest
GetNodeWithAdmin
ReadPropertyTest
SQL2DescendantSearchTest
SQL2SearchTest
SimpleSearchTest

> SegmentStore cache does not take "string" map into account
> ----------------------------------------------------------
>
>                 Key: OAK-3007
>                 URL: https://issues.apache.org/jira/browse/OAK-3007
>             Project: Jackrabbit Oak
>          Issue Type: Bug
>          Components: segmentmk
>            Reporter: Thomas Mueller
>             Fix For: 1.3.3
>
>         Attachments: OAK-3007-2.patch, OAK-3007-3.patch, OAK-3007.patch
>
>
> The SegmentStore cache size calculation ignores the size of the field Segment.string
(a concurrent hash map). It looks like a regular segment in a memory mapped file has the size
1024, no matter how many strings are loaded in memory. This can lead to out of memory. There
seems to be no way to limit (configure) the amount of memory used by strings. In one example,
100'000 segments are loaded in memory, and 5 GB are used for Strings in that map.
> We need a way to configure the amount of memory used for that. This seems to be basically
a cache. OAK-2688 does this, but it would be better to have one cache with a configurable
size limit.



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