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From "Jukka Zitting (JIRA)" <j...@apache.org>
Subject [jira] Commented: (JCR-1604) NameImpl improvements
Date Fri, 16 May 2008 08:58:55 GMT

    [ https://issues.apache.org/jira/browse/JCR-1604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12597392#action_12597392
] 

Jukka Zitting commented on JCR-1604:
------------------------------------

I chatted with Stefan about this, and he mentioned at least the interning of namespace strings
being based on solid benchmarks, so we should keep it.

The other things might also be worth keeping, especially if we put some effort in reducing
the number of separate Name instances kept around.

The background for this proposal is that I've been looking at ways of reducing the memory
impact of large transient spaces (or large item caches), and reducing the size of NameImpl
would contribute a bit (~1%).

> NameImpl improvements
> ---------------------
>
>                 Key: JCR-1604
>                 URL: https://issues.apache.org/jira/browse/JCR-1604
>             Project: Jackrabbit
>          Issue Type: Improvement
>          Components: jackrabbit-jcr-commons
>            Reporter: Jukka Zitting
>            Priority: Minor
>         Attachments: NameImpl.patch
>
>
> I'd like to propose the following changes to NameImpl in jackrabbit-jcr-commons:
> 1) Don't intern the namespace string. Most often the namespace string is in any case
coming from a namespace registry, so there aren't that many copies of the same strings lying
around. Also, I don't think the performance impact on NameImpl.equals() is significant even
if there are multiple copies of the same namespace string.
> 2) Don't memorize the hash code. Since String already memorizes its hash code, the cost
of NameImpl.hashCode() is just a few bytecode instructions. I don't think the performance
benefit is worth the extra complexity and memory overhead.
> 3) Don't memoize the string representation. NameImpl.toString() method is typically only
invoked when debugging or when serializing name values. In both cases the CPU overhead of
recreating the string is insignificant and IMHO not worth the memory overhead .
> I'll attach the patch.

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