PI50525: EXCESSIVE APPEND CALLS CAUSE HIGH CPU WHEN USING INTELLIGENT MANAGEMENT AND PERFORMANCE MONITORING

8.5.5.8: WebSphere Application Server V8.5.5 Fix Pack 8
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
8.5.5.20: WebSphere Application Server V8.5.5.20
8.5.5.18: WebSphere Application Server V8.5.5 Fix Pack 18
8.5.5.19: WebSphere Application Server V8.5.5 Fix Pack 19
8.5.5.16: WebSphere Application Server V8.5.5 Fix Pack 16
8.5.5.21: WebSphere Application Server V8.5.5.21

APAR status

• Closed as program error.

Error description

• Intelligent Management calls PMI appendCustomSetString method
  for every new URI request within 15 seconds poll interval for
  each module. This drives many frequent calls to
  appendCustomSetString and this causes hung Alarm threads and
  high CPU.
  
  The related AlarmThread is as follows:
  AlarmThreadMo W   UTLS0008W: The return of alarm thread
  "Deferrable Alarm : 0" (0000007f) to the alarm thread pool has
  been delayed for 12114 milliseconds. This may be preventing
  normal alarm function within the application server.
  The alarm listener stack trace is as follows:
  at
  com.ibm.ws.xd.pmi.async.server.PmiPost.getStatsInternal(Publis
  her.java:3752)
  at
  com.ibm.ws.xd.pmi.async.server.PmiPost.getStats(Publisher.java:3
  650)
  at
  com.ibm.ws.xd.pmi.async.server.PmiPost.doPost(Publisher.java:355
  8)
  at
  com.ibm.ws.xd.pmi.async.server.PmiPost$1.run(Publisher.java:3343
  )
  at
  com.ibm.ws.security.auth.ContextManagerImpl.runAs(ContextManager
  Impl.java:5474)
  

Local fix

• The code is being fixed by calling appendLockCustomSetString
  method provided by PMI.
  
  This will fix the unnecessary call to PMI appendCustomSetString.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server of Intelligent Management and        *
  *                  Performance Monitoring Infrastructure       *
  *                  (PMI)                                       *
  ****************************************************************
  * PROBLEM DESCRIPTION: Intelligent Management calls the PMI    *
  *                      appendCustomSetString method            *
  *                      frequently, causing hung threads and    *
  *                      high CPU.                               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Intelligent Management calls the PMI appendCustomSetString
  method for every new URI request within 15 seconds poll
  interval for each module. This drives many frequent calls to
  appendCustomSetString and this causes hang Alarm threads and
  high CPU.
  The threads are hung at the following :
  com.ibm.ws.pmi.server.PmiCollaboratorImpl.appendCustomSetString(
  PmiCollaboratorImpl.java:218)
  

Problem conclusion

• This APAR requires prereq APAR PI48619.
  
  The fix removes calling "appendCustomSetString" by Intelligent
  Management to enable PMI metrics but calls new method
  "perhapsCallPmiAppendLock" exposed by PMI once to enable
  the metrics and it remains enabled.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 8.5.5.8.  Please refer to the Recommended Updates
  page for delivery information:
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

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

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R850 PSY

     UP