IZ73156: NATIVE OOMS ON NON-ZOS 64-BIT JVMS USING -XCOMPRESSEDREFS CAUSED BY JAVA HEAP ALLOCATED IN 32-BIT SPACE

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  All JVM allocations from native memory are occurring below the 4
  GB memory mark.  When the heap is in this range as well this
  leads to a out of memory error when in fact there is still
  plenty of free native memory, just none in the 0-4GB region.
  

Local fix

Problem summary

• This problem can occur on any non-zOS 64 bit JVM running in
  compressed reference mode (using the -Xcompressedrefs option,
  which was introduced in IBM Java 6.0).
  
  A compressed references JVM will make some native memory
  requests in the 0-4GB range only, for performance reasons. When
  this range is exhausted a native OutOfMemoryError will be
  thrown with the detail message "native memory exhausted".
  
  Under some circumstances the Java Heap can be allocated in the
  0-4GB range, reducing the amount of memory available for these
  allocations and presenting the symptom earlier than necessary.
  

Problem conclusion

• The JVM has been updated to include an option for specifying the
  base memory address for the heap.
  Example for starting at the 4GB memory mark
  -Xgc:preferredHeapBase=0x100000000
  If the heap cannot be allocated in a contiguous block at the
  preferredHeapBase address specified, an error occurs detailing a
  GC allocation failure startup.
  
  This defect will be fixed in:
  6.0.0 SR7
  

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

• R600 PSY

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