IJ11619: CONCURRENT SCAVENGE HANG WHEN GC DOES NOT MOVE OBJECT IN J9READBARRIER

APAR status

• Closed as program error.

Error description

• Error Message: The application hangs when running with
  -Xgc:concurrentScavenge on a z14 machine typically with smaller
  heaps.
  .
  Stack Trace: N/A
  .
  Collecting multiple core dumps will show we are stuck in a look
  executing J9ReadBarrier in an attempt to evacuate an object when
  the heap is entirely full.
  

Local fix

• Increasing the heap size may make the problem much less likely
  to happen, however the only workaround for this issue is to
  disable concurrent scavenge by removing the
  -Xgc:concurrentScavenge option from the command line arguments.
  

Problem summary

• The JIT compiler was not aware of the situation in which
  J9ReadBarrier was unable to evacuate an object and would return
  back to the JIT mainline to re-execute a guarded load.
  

Problem conclusion

• This problem has been addressed by
  https://github.com/eclipse/openj9/pull/3763
  .
  This APAR will be fixed in the following Java Releases:
   8 SR5 FP27 (8.0.5.27)
  .
  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:

• Fixed component name

  JIT

• Fixed component ID

  620700124

Applicable component levels