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From "Stefan Guggisberg (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JCR-1663) REFERENCE properties produce duplicate strings in memory
Date Thu, 26 Jun 2008 08:04:45 GMT

    [ https://issues.apache.org/jira/browse/JCR-1663?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12608329#action_12608329
] 

Stefan Guggisberg commented on JCR-1663:
----------------------------------------

at one point we actually did intern the local Name part. we ran into the said perm space issues
at some installations, that's why we only intern the namespace uri. that helped to considerable
improve performance (equals() method) and reduce memory footprint.

therefore, -1 for interning local name strings

i agree with jukka that NameFactory maintaining a chache of commonly used names would be a
good alternative.
however, unless there's a real issue, i'd prefer to stick with interning namespace uri's.

> REFERENCE properties produce duplicate strings in memory
> --------------------------------------------------------
>
>                 Key: JCR-1663
>                 URL: https://issues.apache.org/jira/browse/JCR-1663
>             Project: Jackrabbit
>          Issue Type: Improvement
>          Components: jackrabbit-core, jackrabbit-spi-commons
>    Affects Versions: 1.4, core 1.4.5
>            Reporter: Roman Puchkovskiy
>
> When reference property is loaded from PM, Serializer.deserialize(NodeReferences, InputStream)
is called, which calls PropertyId.valueOf(String), which in turn calls NameFactoryImpl.create(String)
which finally splits a full property name to namespace and local name. Namespace is internalized,
but local name is not (comments say that this is done to avoid perm space overfilling).
> So, in the end, a new String instance is created for local name. This leads to considerable
memory waste when repository has a lot of nodes with REFERENCE properties.
> It seems that local name part could be internalized here too because in the most repositories
it's not allowed to create properties with arbitrary names, so the danger of perm space exhaust
does not seem to be an argument.
> As for ways to resolve this, maybe a new NameFactory implementation could be created
which would be used for properties only (and, possibly, mainly in the PropertyId.valueOf(String))
which would extend an existing NameFactoryImpl overriding its create(String) method.
> What do you think about all this?

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