IJ15356: MEMORY_COLLECTION_THRESHOLD_EXCEEDED NOTIFICATION FOR MEMORYPOOLMXBEAN IS TRIGGERED MORE THAN EXPECTED

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  after setting collection threshold on the memory pool,
  MEMORY_COLLECTION_THRESHOLD_EXCEEDED notification is always
  triggered, even if there is no low memory case. It happens on
  Java 8 SP5 or later.
  

Local fix

• add -XX:+HeapManagementMXBeanCompatibility option in command
  line to avoid the problem
  

Problem summary

• the collection threshold has been checked after every GC, even
  the GC does not try to reclaim the memory pool (regularly the
  memory pool would reach to full before triggering the related GC
  to reclaim the memory). It would cause the notification to be
  possibly triggered every time before the GC attempts to reclaim
  from the memory pool.
  

Problem conclusion

• MXBeans code has been updated to only check the collection
  threshold after GC reclaims the memory from the memory pool.
  .
  This APAR will be fixed in the following Java Releases:
     8    SR6 FP10  (8.0.6.10)
  .
  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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