RFR: JDK-8087291: InitialBootClassLoaderMetaspaceSize and CompressedClassSpaceSize should be checked consistent from MaxMetaspaceSize

[Yasumasa Suenaga]

webrev is here:
  http://cr.openjdk.java.net/~ysuenaga/JDK-8087291/webrev.00/

Yasumasa


On 2015/06/12 12:25, Yasumasa Suenaga wrote:
> Hi all,
> 
> This issue is related to [1].
> 
> I booted Tomcat 8 with "-XX:MaxMetaspaceSize=5m -XX:+PrintGCDetails", but it failed.
> I checked GC log, Java heap and Metaspace was NOT exhausted.
> 
> ------------
> [Full GC (Last ditch collection) [Tenured: 1049K->1049K(10944K), 0.0050992 secs] 1049K->1049K(15936K), [Metaspace: 4871K->4871K(1056768K)], 0.0051411 secs] [Times: user=0.01 sys=0.00, real=0.00 secs]
> [Full GC (Metadata GC Threshold) [Tenured: 1049K->1049K(10944K), 0.0050587 secs] 1049K->1049K(15936K), [Metaspace: 4871K->4871K(1056768K)], 0.0051023 secs] [Times: user=0.00 sys=0.00, real=0.01 secs]
> [Full GC (Last ditch collection) [Tenured: 1049K->1049K(10944K), 0.0050200 secs] 1049K->1049K(15936K), [Metaspace: 4871K->4871K(1056768K)], 0.0050613 secs] [Times: user=0.01 sys=0.00, real=0.00 secs]
> 
> Exception: java.lang.OutOfMemoryError thrown from the UncaughtExceptionHandler in thread "main"
> ------------
> 
> My environment:
>       Fedora22 x86_64
>        - kernel-4.0.4-303.fc22.x86_64
>        - glibc-2.21-5.fc22.x86_64
>        - java-1.8.0-openjdk-1.8.0.45-39.b14.fc22.x86_64
>        - apache-tomcat-8.0.23
> 
> The Compressed ClassSpace is a part of Metaspace.
> The size of the Compressed ClassSpace is included in the comparison with MaxMetaspaceSize only
> when the space is committed [1].
> However, users cannot know their incorrect parameter(s) until memory space will be committed.
> 
> Compressed ClassSpace is continuous memory space, and its default value is 1GB.
> In case of Linux, it affects overcommit memory. It will be cause of OOM-killer at the worst case.
> 
> So I want to alert inconsistency metaspace setting at early as possible.
> 
> I'm jdk9 committer, but I'm not employee at Oracle.
> So I need a Sponsor.
> 
> 
> Thanks,
> 
> Yasumasa
> 
> 
>   [1] http://mail.openjdk.java.net/pipermail/hotspot-gc-dev/2015-June/013817.html
>