[jira] [Updated] (MIME4J-302) MessageBuilder::parse repeatedly calls toLowerCase on header names

["Benoit Tellier (Jira)" <mi...@james.apache.org>]

     [ https://issues.apache.org/jira/browse/MIME4J-302?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Benoit Tellier updated MIME4J-302:
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    Attachment: mime4j-302-after.png
                mime4j-302-before.png

> MessageBuilder::parse repeatedly calls toLowerCase on header names
> ------------------------------------------------------------------
>
>                 Key: MIME4J-302
>                 URL: https://issues.apache.org/jira/browse/MIME4J-302
>             Project: James Mime4j
>          Issue Type: Improvement
>          Components: core, dom
>            Reporter: Benoit Tellier
>            Priority: Major
>              Labels: perf
>         Attachments: mime4j-302-after.png, mime4j-302-before.png
>
>
> As attached I was surprised MIME4J parsing spends 18% of its time calling toLowerCase on header names. This represents 12% of allocated memory.
> By holding the lowerCased name as part of the field name, and doing lazy initialization on it we can get this down to 6%.
> Also, an optimization implemented in MaximalBodyDescriptor aims at reducing the costs of toLowerCase calls: upon known header names lookup the lowercase version of the field instead of the normal version to benefit optimizations (calling toLowerCase on a lowerCase string do not do allocation, it just iterates String content). It might be worth generalizing it.



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