PM51393: SYSTEM ENQ CREATED FOR EACH HTTP SESSION EVEN WHEN ONLY ONE SERVANT CAN EXIST.

8.0.0.4: WebSphere Application Server V8.0 Fix Pack 4
8.5.0.1: WebSphere Application Server V8.5 Fix Pack 1
8.0.0.5: WebSphere Application Server V8.0 Fix Pack 5
8.5.0.2: WebSphere Application Server V8.5 Fix Pack 2
8.0.0.6: WebSphere Application Server V8.0 Fix Pack 6
8.0.0.7: WebSphere Application Server V8.0 Fix Pack 7
8.0.0.8: WebSphere Application Server V8.0 Fix Pack 8
8.0.0.9: WebSphere Application Server V8.0 Fix Pack 9
8.0.0.10: WebSphere Application Server V8.0 Fix Pack 10
8.0.0.11: WebSphere Application Server V8.0 Fix Pack 11
8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15

APAR status

• Closed as program error.

Error description

• Customer in an ND environment runs a server with only 1 servant.
  
  HTTP load tests are performed.
  
  An unusually high number of System ENQs are obtained, and
  reported to the MVS Operator in message
  
  *ISG368E THE CONCURRENT AUTHORIZED REQUEST COUNT FOR ASID 0093
   HAS EXCEEDED THE 80 PERCENT THRESHOLD OF THE SYSTEM-WIDE
   MAXIMUM 250000.
  
  ASID 0093 is the WebSphere Servant region address space
  running the load test.
  
  Analysis of the console dump with IPCS command IP GRSDATA for
  ASID(x'93')  shows many thousands of System ENQs that look
  similar to these:
  
  AAAAAAAAAAAAAAAA00000FFF00000002000000FF--0AaihrKplxxMlB9bwevni
  AAAAAAAAAAAAAAAA00000FFF00000002000000FF--1BbMerULYUVdEBnWiOora
  AAAAAAAAAAAAAAAA00000FFF00000002000000FF--1CcnnrY-kGa2nNdOC8LcW
  AAAAAAAAAAAAAAAA00000FFF00000002000000FF--4DdHMrTnbWmkyGMZmFcwm
  AAAAAAAAAAAAAAAA00000FFF00000002000000FF--4e8jZrSyPSaybaf16wV0M
  
  These System ENQs are for HTTP Sessions.
  

Local fix

• Run the HTTP Load tests in a server defined as a base appserver
  (not in an ND environment)
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server V8.0                                 *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance overhead in routing         *
  *                      requests with session affinity from     *
  *                      the Controller to the appropriate       *
  *                      Servantin cases where there is only     *
  *                      one                                     *
  *                      Servant.                                *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When using a WebSphere environment with only one
  Servant,needless overhead is created determining
  which Servant to route requests to from the Controller.
  This is unneeded when there is only one possible Servant.
  

Problem conclusion

• Code has been updated to skip unneeded overhead when the server
  is running in an environment where only one servant exists.
  
  APAR PM51393 is currently targeted for inclusion in
  Service Level (Fix Pack) 8.0.0.4 of WebSphere Application
  Server V8.0.
  
  Please refer to the Recommended Updates page for delivery
  information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  
  In addition, please refer to URL:
  http://www.ibm.com/support/docview.wss?rs=404&uid=swg27006970
  for Fix Pack PTF information.
  

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

  WEBSPHERE FOR Z

• Fixed component ID

  5655I3500

Applicable component levels

• R800 PSY

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