[jboss-jira] [JBoss JIRA] (LOGTOOL-132) Support low-metaspace bundles/classes

[James Perkins (JIRA)]

    [ https://issues.jboss.org/browse/LOGTOOL-132?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13523187#comment-13523187 ] 

James Perkins commented on LOGTOOL-132:
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I'll see what making the class final does (I'll have to read what Andrew wrote about it again too). 

On my preliminary test, not having a final test but loading properties for translations, the metaspace size for the classes decreases about 11%, but the total metaspace size increased by about 1%. I'll test making it final and see what the difference is. I've not tested performance at all yet, but I'll definitely test that too. I do have no doubt there will be a performance impact, but hopefully we can keep it at a minimum.

One option *might* be we have a flag which will generate the original implementation for performance or lookups if metaspace is the concern.

> Support low-metaspace bundles/classes
> -------------------------------------
>
>                 Key: LOGTOOL-132
>                 URL: https://issues.jboss.org/browse/LOGTOOL-132
>             Project: Log Tool
>          Issue Type: Enhancement
>            Reporter: David Lloyd
>            Priority: Critical
>
> Metaspace is at a premium in the application server environment, and the number one consumer is presently generated log classes.
> Introduce a leaner variation on generated classes with the following requirements:
> * The generated class must be {{final}}
> * The generated class must contain no message strings
> * The generated class must accept both a {{Logger}} and a {{Locale}}, and load its resources from a file based on that information
> * The usage of Java 8's locale lookup functionality should be considered, to support language tags etc.; a helper utility could be introduced into {{jboss-logging}} for this
> Here are some implementation ideas:
> * Option 1: The resource files contain only messages, one per line, loaded directly into a {{String[]}} instance field in the implementation class; each logging method uses a hard-coded array index to access its message
> ** A key advantage is that the implementation class is very small, and consumes very little metaspace; also, it is fast, requiring only an array lookup to acquire the string
> ** A disadvantage is, any change to the message set invalidates all the locale files, which must then be regenerated
> ** Also, each locale file must contain all messages, unless a fallback mechanism is used (e.g. an empty line signifies that the string should come from the parent locale)
> * Option 2: The resource files contain key-value pairs, with the key being equal to the method name
> ** Advantage: the file is not invalidated if a key is added, and sub-locales can inherit more easily from parent locales
> ** Disadvantage: the added overhead of mapping lines to methods (for example, using a switch statement to map method names to fixed indexes, or loading the messages into a hash table e.g. {{HashMap}}) will fill metaspace or impact performance, or both



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