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PI92979: HIGH CPU DUE TO THE CLASSLOADER STACK

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • gh CPU due to the classloader stack
    

Local fix

  • na
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server Hang Detection.                      *
    ****************************************************************
    * PROBLEM DESCRIPTION: The application server may              *
    *                      exhibit high CPU utilization when       *
    *                      Hang Detection is enabled.              *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    The Thread Monitor may loop indefinitely while determining
    the state of a managed thread.  When this problem occurs you
    will find a log containing an FFDC event like that shown below,
    where the failure call stack indicates a
    ConcurrentModificationException occurred while determining a
    managed thread is clear (no longer hung.)  A similar
    exception may occur while determining a managed thread is hung.
    FFDC Exception:java.util.ConcurrentModificationException
    SourceId:com.ibm.ws.runtime.component.ThreadMonitorImpl
    ProbeId:439
    ...
    java.util.ConcurrentModificationException
    at
    java.util.Vector$Itr.checkForComodification(Vector.java:1195)
    at
    java.util.Vector$Itr.next(Vector.java:1148)
    at
    com.ibm.ws.runtime.component.ThreadMonitorImpl.threadIsClear(Thr
    eadMonitorImpl.java:676)
    at
    com.ibm.ws.runtime.component.ThreadPoolMgrImpl$ThreadPoolMonitor
    Adapter.clearThread(ThreadPoolMgrImpl.java:988)
    at
    com.ibm.ws.util.ThreadPool$Worker.disableHungThreadDetection(Thr
    eadPool.java:1968)
    at
    com.ibm.ws.util.ThreadPool$Worker.threadReturned(ThreadPool.java
    :1940)
    at
    com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1907)
    The problem may be circumvented by disabling Hang Detection on
    the failing application server. Hang Detection is disabled
    whenever custom property
    "com.ibm.websphere.threadmonitor.interval" is set to zero (0)
    in the application server configuration.  Instructions to
    disable Hang Detection are provided in topic "Configuring the
    hang detection policy" of the WebSphere Application Server
    v8.5.5 Knowledge Center:
    https://www.ibm.com/support/knowledgecenter/en/SSAW57_8.5.5/com.
    ibm.websphere.nd.doc/ae/ttrb_confighangdet.html
    

Problem conclusion

  • Apply APAR PI92979 to ensure the Thread Monitor of an
    application server does enter an infinite loop while
    detecting hung threads.
    
    The fix for this APAR is currently targeted for inclusion in
    fix packs 8.5.5.14 and 9.0.0.8.  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 number

    PI92979

  • Reported component name

    WEBS APP SERV N

  • Reported component ID

    5724H8800

  • Reported release

    850

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-01-26

  • Closed date

    2018-02-16

  • Last modified date

    2018-02-16

  • 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

  • R900 PSY

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"850","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
19 October 2021