[jboss-jira] [JBoss JIRA] (WFLY-4681) Reevaluation of java memory settings

[Sanne Grinovero (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-4681?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13148255#comment-13148255 ] 

Sanne Grinovero commented on WFLY-4681:
---------------------------------------

Hello all,
I've been checking the GC logs generated by starting WildFly 10.0.0.CR5 in standalone mode, and I can see the metaspace is being exausted several times, which triggers full GCs before the JVM decides to scale up the metaspace.

By setting {{-XX:MetaspaceSize=64m}} I do benefit from a ~15% faster boot time.

According to JConsole a just-started WildFly instance requires approximately 55MB of metaspace, while the default is around 20MB according to {{-XX:+PrintFlagsFinal}} on my machine (JDK8, 64bit linux). So I'd suggest setting this to 64mb as a starting point, it will of course scale up automatically depending of deployed application needs but this is the least it needs at boot to prevent it from chocking on those full GCs.

> Reevaluation of java memory settings
> ------------------------------------
>
>                 Key: WFLY-4681
>                 URL: https://issues.jboss.org/browse/WFLY-4681
>             Project: WildFly
>          Issue Type: Bug
>          Components: Server
>    Affects Versions: 10.0.0.Alpha1
>            Reporter: Marek Kopecký
>            Assignee: Andrig Miller
>
> Based on [~ctomc]'s comment in https://issues.jboss.org/browse/JBEAP-149,
> perf team should do some testing and suggest best values for java memory settings in WildFly (-Xms, -Xmx, ...). This settings need to be completely reevaluated as EAP7 moved to JDK8 as requirement.
> JDK8 doesn't have PermGen space anymore but metaspace, this completely changes how memory settings need to be tuned.



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