IV85620: A KEY WAS INCORRECTLY REMOVED FROM A WEAKHASHMAP TABLE

APAR status

• Closed as program error.

Error description

• Error Message: A NullPointerException is received if the
  application code uses the key to retrieve the entry value and
  de-reference the value.
                  The following snap trace entry can be found in
  the Snap traces:
                     j9mm.124            Entry
  >Trc_MM_SynchronizeGCThreadsAndReleaseMaster Entry from:
  ConcurrentOverflow.cpp:229
                  The verbose GC log shows large number of objects
  are finalized:
                      <pending-finalizers system="61"
  default="14683622" reference="5" classloader="0" />
  .
  Stack Trace: N/A
  .
  

Local fix

• This issue can be worked around using -Xgcworkpackets option to
  increase size of work packet so that the buffer overflow does
  not happen.
                  The default size of the work packet is
  proportional to the heap size.  For a 6 GB heap, the default
  size is 15725. In one situation, the overflow was avoided using
  -Xgcworkpackets50000.  Note this will consume approximately 150
  MB extra native memory.
  

Problem summary

• The problem is caused when the reference objects has been scaned
  more than once during the garbage collector's work packets
  overflowing.
  

Problem conclusion

• The JVM has been updated so that the garbage collector properly
  handles the work packets buffer overflow.
  
  .
  This APAR will be fixed in the following Java Releases:
     8    SR3 FP10  (8.0.3.10)
     7 R1 SR3 FP50  (7.1.3.50)
  .
  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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