PM39440: HIGH CPU DUE TO GC CAUSED BY EXCESSIVE INSTANCES OF JAVA OBJECT COM.IBM.ISECURITYLOCALOBJECTCSIV2UTILITYIMPL.SESSIONMANAGER

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Customer automation detects excessive CPU consumption in a
  WebSphere Servant region.  VerboseGC report shows GC happening
  every second.  Java heap analysis reports
  
  One instance of "com.ibm.ISecurityLocalObjectCSIv2UtilityImpl.
  
  SessionManager" loaded by "<system class loader>" occupies
  186,574,312 (53.90%) bytes. The memory is accumulated in one
  instance of "java.util.Hashtable$Entry[]" loaded by
  "<system
  class loader>".
  
  Keywords
  java.util.Hashtable$Entry[]
  com.ibm.ISecurityLocalObjectCSIv2UtilityImpl.SessionManager
  
  
   Shortest Paths To the Accumulation Point
  Class Name Shallow Heap Retained Heap
  java.util.Hashtable$Entry[4] @ 0x378dcca8 32 186,571,552
  com.ibm.ISecurityLocalObjectCSIv2UtilityImpl.ConnectionTable @
  0x378d42a8 40 186,571,592
  com.ibm.ISecurityLocalObjectCSIv2UtilityImpl.SessionManager @
  0x378c7290 64 186,574,312
  com.ibm.ISecurityLocalObjectBaseL13Impl.VaultImpl @ 0x37889328
  64 584
  com.ibm.ISecurityLocalObjectGSSUPImpl.SecurityContextImpl @
  0x49e72188
  
  Eventually the growth in these objects would lead to OOM
  java.lang.OutOfMemoryError.
  
  Customer expects only 1000 of these SessionManager objects
  because they have set
  com.ibm.websphere.security.util.csiv2SessionCacheIdleTime=60000
  com.ibm.websphere.security.util.csiv2SessionCacheLimitEnabled=tr
  ue
  com.ibm.websphere.security.util.csiv2SessionCacheMaxSize=1000
  
  cache idle time is 60000 milliseconds.
  session cache limit is enabled.
  session cache max size is 1000
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server V7.0                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: CSIv2 Session objects in Session Cache  *
  *                      might not be evicted even they meet     *
  *                      eviction criteria.                      *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When the custom property
  com.ibm.websphere.security.util.csiv2SessionCacheLimitEnabled
  is set to true, there was no code path which checks the size
  of cache and evicts cache entry upon inserting cache entry to
  make sure the number of cache entris was with the limit. As a
  result, number of cache enries kept increasing.
  

Problem conclusion

• With this fix, prior to insert cache entry, the code checks
  number of cache entries, and if it's on the limit, remove an
  entry which is not used for the longest time to make sure that
  number of cache entry is within the specified limit.
  
  APAR PM39440 is currently targeted for inclusion in Service
  Level (Fix Pack) 7.1.0.21 of WebSphere Application Server V7.0.
  
  Please refer to URL:
  //www.ibm.com/support/docview.wss?rs=404&uid=swg27006970
  for Fix Pack availability.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  PM39363

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  WEBSPHERE FOR Z

• Fixed component ID

  5655I3500

Applicable component levels

• R700 PSY UK74996

     UP12/01/18 P 1201

Fix is available

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