[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=13522495#comment-13522495 ] 

James Perkins edited comment on LOGTOOL-132 at 1/23/18 9:10 AM:
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I'll do some experimenting today. I kind of wonder how much metaspace we'll really save by removing the {{*$str()}} methods. By removing those methods there's definitely going to be more I/O happening.

By removing the static strings and just returning the string from the {{*$str()}} method as well as creating a static method in jboss-logging to trim the stack trace I was able to save some metaspace.

*Before Change*
||Index||Super||Total||ClassName||
|604|5115|136592|org.jboss.as.server.logging.ServerLogger_$logger|
|1561|5115|97312|org.jboss.as.domain.management.logging.DomainManagementLogger_$logger|

*After Change*
||Index||Super||Total||ClassName||
|602|5104|127624|org.jboss.as.server.logging.ServerLogger_$logger
|1562|5104|91152|org.jboss.as.domain.management.logging.DomainManagementLogger_$logger|


was (Author: jamezp):
I'll do some experimenting today. I kind of wonder how much metaspace we'll really save by removing the {{*$str()}} methods. By removing those methods there's definitely going to be more I/O happening.

By removing the static strings and just returning the string from the {{*$str()}} method as well as creating a static method in jboss-logging to trim the stack trace I was able to save some metaspace.

*Before Change*
||Index||Super||Total||ClassName||
|604|5115|136592|org.jboss.as.server.logging.ServerLogger_$logger|
|602|5104|127624|org.jboss.as.server.logging.ServerLogger_$logger

*After Change*
||Index||Super||Total||ClassName||
|1561|5115|97312|org.jboss.as.domain.management.logging.DomainManagementLogger_$logger|
|1562|5104|91152|org.jboss.as.domain.management.logging.DomainManagementLogger_$logger|

> 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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