IV78553: JVM crashes at startup when using -Xshareclasses and the cache has data from a VM running in the opposite compressedrefs mode

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: TR_J9VMBase::matchRAMclassFromROMclass
  
  TR_IPBCDataCallGraph::loadFromPersistentCopy
  TR_IProfiler::profilingSample
  .
  

Local fix

• Use different cache names for 64-bit compressedrefs and
  non-compressedrefs. If the JVM crashes every time it starts,
  destroy the existing shared cache to resolve the crash. A new
  shared cache will be created automatically.
  

Problem summary

• This problem is caused by sharing the same cache between 64-bit
  compressedrefs and non-compressedrefs JVMs. This can occur when
  switching from compressedrefs to non-compressedref or
  vice-versa, which occurs either explicitly by using the
  -Xcompressedrefs or -Xnocompressedrefs command line options, or
  when changing the -Xmx parameter to be over or under the 25g
  boundary. Specifying -Xmx25g or lower invokes the compressedrefs
   JVM, and values above 25g invoke the non-compressedrefs JVM.
  

Problem conclusion

• The VM has been updated to stop sharing the same cache between
  64-bit compressedrefs and non-compressedrefs. Two different
  cache files are created with different names. The separate
  caches can be seen in the -Xshareclasses:listAllCaches output,
  with the type of cache (compressed, non-compressed, or default)
  shown in the feature column. For more details please see the IBM
   SDK Java Technology Edition User Guide.
  
  .
  This APAR will be fixed in the following Java Releases:
     8    SR2 FP10  (8.0.2.10)
  .
  Contact your IBM Product's Service Team for these Service
  Refreshes and Fix Packs.
  For those running stand-alone, information about the available
  Service Refreshes and Fix Packs can be found at:
             https://www.ibm.com/developerworks/java/jdk/
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  J9 COMMON CODE

• Fixed component ID

  620700127

Applicable component levels

• R270 PSY

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