IV20824: JAVAHEAP ITERATOR RETURNS MULTIPLE INSTANCES OF THE SAME HEAP IN 2.3/2.4 JVMS

APAR status

• Closed as program error.

Error description

• Error Message: N/A
  .
  Stack Trace: N/A
  .
  Using jdmpview's info heap command the following output is
  printed out:
    Heap #1:  Default@80875cce8
     Section #1:  Heap extent at 0x827f01000 (0x18000000 bytes)
      Size:        402653184 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #2:  Heap extent at 0x847f01000 (0x7333000 bytes)
      Size:        120795136 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #3:  Heap extent at 0x84f234000 (0xccd000 bytes)
      Size:        13422592 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
    Heap #2:  Default@80875cb08
     Section #1:  Heap extent at 0x827f01000 (0x18000000 bytes)
      Size:        402653184 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #2:  Heap extent at 0x847f01000 (0x7333000 bytes)
      Size:        120795136 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #3:  Heap extent at 0x84f234000 (0xccd000 bytes)
      Size:        13422592 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
    Heap #3:  Default@80875cbf8
     Section #1:  Heap extent at 0x827f01000 (0x18000000 bytes)
      Size:        402653184 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #2:  Heap extent at 0x847f01000 (0x7333000 bytes)
      Size:        120795136 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
     Section #3:  Heap extent at 0x84f234000 (0xccd000 bytes)
      Size:        13422592 bytes
      Shared:      false
      Executable:  false
      Read Only:   false
  Note that all 3 heaps overlap in memory and there actually
  should only be one heap with three sections.
  The above data was obtaied using JavaRuntime's getHeaps()
  method, and subsequently JavaHeap's getSections().
  

Local fix

• Note that this only affect DDR DTFJ when trying to read cores
  from 2.3/2.4 JVMs.  However DDR DTFJ is only shipped in 2.6 and
  up.
  Thus this problem only appears to people using 2.6 JVMs looking
  at 2.3/2.4 JVM core files.
  The fix/workaround is therefore to use java626sr2/java7sr1 or up
  when using DTFJ/jdmpview.
  

Problem summary

• The problem is caused by an faulty implementation of
  JavaRunTime.getHeaps() which returns 'ImageSections' instead of
  the proper 'DTFJavaHeaps'.
  

Problem conclusion

• This defect will be fixed in:
  7.0.0 SR1
  6.0.1 SR2
  .
  Fixed by having DTFJJavaHeaps be represented by J9MemorySpaces
  and ImageSections be represented by J9MemorySegments.
  

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

• R260 PSY

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