[jboss-jira] [JBoss JIRA] (WFLY-5955) Include -XX:MetaspaceSize in our default vm settings

[Brian Stansberry (JIRA)]

     [ https://issues.jboss.org/browse/WFLY-5955?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Brian Stansberry moved WFCORE-1279 to WFLY-5955:
------------------------------------------------

          Project: WildFly  (was: WildFly Core)
              Key: WFLY-5955  (was: WFCORE-1279)
      Component/s: Server
                       (was: Server)
    Fix Version/s: 10.0.0.Final
                       (was: 3.0.0.Alpha1)
                       (was: 2.0.6.Final)


> Include -XX:MetaspaceSize in our default vm settings
> ----------------------------------------------------
>
>                 Key: WFLY-5955
>                 URL: https://issues.jboss.org/browse/WFLY-5955
>             Project: WildFly
>          Issue Type: Bug
>          Components: Server
>            Reporter: Brian Stansberry
>            Assignee: Brian Stansberry
>             Fix For: 10.0.0.Final
>
>
> JDK 8 no longer has a perm gen, but it does have a "Metaspace" area of native memory where it stores some of the types of data previously stored in perm gen, class metadata in particular.
> The default size of this is, I believe 21MB on a 64 bit VM. Full WildFly uses over 50MB, excluding apps. The VM will increase the size once it gets over a certain percentage full, but it will do a full, stop-the-world GC before increasing. This means full WildFly has two full GCs as part of boot.
> The -XX:MetaspaceSize JVM option allows the minimum size to be set. Using a reasonable value for this will help avoid unnecessary full GCs.
> I'm not sure the best value to use. A minimum of 80MB was enough to avoid a full GC during a boot of standalone-full-ha.xml. But then any sort of deployments will trigger a full GC. OTOH, our host.xml jvm elements have historically included a -XX:PermSize setting of 256M, so that's another possible value. Perm Gen and Metaspace aren't completely equivalent (e.g. before JDK 7 perm gen included stuff like interned strings, which are now in the heap.)



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