RFR: 8210926: vmTestbase/nsk/jvmti/scenarios/allocation/AP11/ap11t001/TestDescription.java failed with JVMTI_ERROR_INVALID_CLASS in CDS mode

[coleen.phillimore at oracle.com]

This looks good!
Coleen

On 9/28/18 10:08 AM, Jiangli Zhou wrote:
> Please review the fix for JDK-8210926. This is a bug in the CDS code 
> that's exposed by JvmtiEnv::GetLoadedClasses(), and can be manifested 
> in different failures with the following tests:
>
>   com/sun/jdi/ClassesByName2Test.java
> vmTestbase/nsk/jvmti/scenarios/allocation/AP11/ap11t001/TestDescription.java 
>
>   runtime/RedefineTests/ModifyAnonymous.java
>
> webrev: http://cr.openjdk.java.net/~jiangli/8210926/webrev.00/
> bug: https://bugs.openjdk.java.net/browse/JDK-8210926
>
> SystemDictionary::add_to_hierarchy() sets a InstanceKlass init_state 
> to ‘loaded’ right before it is added to the the SystemDictionary. 
> JvmtiEnv::GetLoadedClasses() retrieves loaded classes’ 
> (InstanceKlasses in 'loaded' state and arrays) mirrors (Class 
> objects). At CDS dump time, a InstanceKlass::_init_state is reset back 
> to 'loaded' state before writing out the archived data. At runtime 
> during loading of a shared class, there is a 'brief' moment 
> JvmtiEnv::GetLoadedClasses() in another thread could see a shared 
> class in ‘loaded’ state without mirror. NULL mirror is not the only 
> issue, other fields of the shared InstanceKlass may not be setup 
> properly before SystemDictionary::add_to_hierarchy(). To fix the 
> issue, we need to reset to _init_state to 'allocated' state before 
> writing out the archived classes at dump time.
>
> Verified the fix with running ClassesByName2Test.java using mach5 
> (thanks Chris for providing the reproducible case). Tested with tier1 
> - tier3 in both default CDS mode and no CDS mode.
>
> Thanks,
> Jiangli
>
>