IJ15420: NURSERY CONTRACT WITH CONCURRENT SCAVENGER

APAR status

• Closed as program error.

Error description

• Error Message: Symptoms vary a lot, but in short, undefined
  behavior of application with Java level exceptions that do not
  make much sense (occur in stable code). Applications with
  frequent usage of Hash Tables and/or Thread level
  synchronization (which rely on internal Monitor Hash Table) are
  affected.
  .
  Stack Trace: N/A
  .
  

Local fix

• Start with high initial Nursery size. Simplest is to set -Xms to
  -Xmx.
  

Problem summary

• Nursery contraction leads to Hash value changing for objects
  that have been allocated and hashed during the just finished
  Concurrent Scavenger cycle.
  

Problem conclusion

• Hash value salt (which is a part of final object Hash value)
  changes are disabled on Nursery contractions.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR5 FP35  (8.0.5.35)
  .
  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

     UP