RFR (S) JDK-8007725 - Klass::restore_unshareable_info() triggers assert(k->java_mirror() == NULL)

[Ioi Lam]

Hi, could someone review this? This fixes a crash related to OOM handling.

Thanks
- Ioi

On 03/11/2013 12:47 PM, Ioi Lam wrote:
> Please review:
> http://cr.openjdk.java.net/~iklam/8007725/null_mirror_001/
>
> Bug: NPG: Klass::restore_unshareable_info() triggers
>     assert(k->java_mirror() == NULL)
>
> http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=8007725
>  or https://jbs.oracle.com/bugs/browse/JDK-8007725
>
>     (The bugs.sun.com page may be unavailable for a couple of days due
>      to recent change of confidentiality status.)
>
> Summary of fix:
>
>     The assert is at:
>
>     --------
>     # Internal Error (src/share/vm/classfile/javaClasses.cpp:527)
>     # assert(k->java_mirror() == NULL) failed: should only assign 
> mirror once
>     java_lang_Class::create_mirror(KlassHandle)
>     Klass::restore_unshareable_info()
>     InstanceKlass::restore_unshareable_info()
>     instanceKlassHandle 
> SystemDictionary::load_shared_class(instanceKlassHandle,Handle)
>     --------
>
>     This happens if during class loading, an OOM happened after
>     Klass::restore_unshareable_info() has called
>     java_lang_Class::create_mirror(), but before the class loading is 
> completed.
>
>     At this point, the class is not in the system dictionary. However the
>     Klass structure is partially initialized.
>
>     If the app tries to load the same class again, the assert happens.
>
>     The fix is to undo all work performed by
>     InstanceKlass::restore_unshareable_info().
>
> Tests executed:
>
>     * JPRT
>     * JCK (vm, lang, api/signaturetest)
>     * UTE (vm.quick.testlist, )
>
> Thanks,
> Ioi