IJ31890: GPF EVENT RAISED FROM METHOD STRINGCOMPARATORFN ()

APAR status

• Closed as program error.

Error description

• Error Message: A GPF event is received during garbage
  collecting.
  .
  Stack Trace: The native stack trace looks like this:
  
          <signal handler called>
          stringComparatorFn ()
          avl_delete ()
          hashTableRemove ()
          hashTableDoRemove ()
  
  MM_CopyForwardSchemeRootClearer::doStringTableSlot(J9Object**,
  GC_HashTableIterator*) ()
          MM_RootScanner::scanStringTable(MM_EnvironmentBase*) ()
          MM_RootScanner::scanClearable(MM_EnvironmentBase*) ()
  
  MM_CopyForwardScheme::workThreadGarbageCollect(MM_EnvironmentVLH
  GC*) ()
  
  MM_ParallelDispatcher::workerEntryPoint(MM_EnvironmentBase*) ()
          dispatcher_thread_proc2(OMRPortLibrary*, void*) ()
  .
  

Local fix

• This issue only happens with GC policy balanced. So the issue
  can be worked around by switching to the default gencon GC
  policy.
  

Problem summary

• The problem is caused in balanced gc policy during String table
  pruning, previously converted to AVL tree format, where GC
  re-balances the tree while some elements have moved during
  copy-forward.
  

Problem conclusion

• The JVM has been updated to prevent the crash from occurring by
  ensuring the AVL tree elements are updated to point to the new
  forwarded position before being re-balanced.
  
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP31  (8.0.6.31)
  .
  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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