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PI64266: MEMORY LEAK DETECTOR PRODUCING FALSE POSITIVE REPORTS

Fixes are available

9.0.0.2: WebSphere Application Server traditional V9.0 Fix Pack 2
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
9.0.0.3: WebSphere Application Server traditional V9.0 Fix Pack 3
9.0.0.4: WebSphere Application Server traditional V9.0 Fix Pack 4
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
9.0.0.5: WebSphere Application Server traditional V9.0 Fix Pack 5
9.0.0.6: WebSphere Application Server traditional V9.0 Fix Pack 6
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
9.0.0.7: WebSphere Application Server traditional V9.0 Fix Pack 7
9.0.0.8: WebSphere Application Server traditional V9.0 Fix Pack 8
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
9.0.0.9: WebSphere Application Server traditional V9.0 Fix Pack 9
9.0.0.10: WebSphere Application Server traditional V9.0 Fix Pack 10
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
9.0.0.11: WebSphere Application Server traditional V9.0 Fix Pack 11
9.0.5.0: WebSphere Application Server traditional Version 9.0.5 Refresh Pack
9.0.5.1: WebSphere Application Server traditional Version 9.0.5 Fix Pack 1
9.0.5.2: WebSphere Application Server traditional Version 9.0.5 Fix Pack 2
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
9.0.5.3: WebSphere Application Server traditional Version 9.0.5 Fix Pack 3
9.0.5.4: WebSphere Application Server traditional Version 9.0.5 Fix Pack 4
9.0.5.5: WebSphere Application Server traditional Version 9.0.5 Fix Pack 5
9.0.5.6: WebSphere Application Server traditional Version 9.0.5 Fix Pack 6

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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • CWMML0020W reported in logs, but no evidence of a classloader
    leak in the dump files.
    
    From reviewing the code of the memory leak detector code for
    detecting these ClassLoader leaks, it is evident that, whilst
    the detector waits for a period of time to allow application
    destroy processing to take place, it does not ensure that a
    garbage collection (GC) cycle has been requested prior to the
    point it assumes that its WeakReference to the ClassLoader
    would be cleared.
    
    As WeakReferences are only cleared (by the VM) during GC,
    ensuring such a GC cycle has occurred prior to checking is
    vital to ensure good accuracy in the reports from the memory
    leak detector.
    
    Adding a suitable request for GC into the memory leak detector
    code immediately prior to its check for leaking application
    ClassLoaders consistently causes it to report that there is no
    leak detected for either the application ClassLoader or the
    ClassLoader of its war.
    

Local fix

  • N/A
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server using its classloader leak           *
    *                  detector.                                   *
    ****************************************************************
    * PROBLEM DESCRIPTION: False positive classloader              *
    *                      leak detector reports in logs.          *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    CWMML0020W reported in logs, but no evidence of a classloader
    leak in the dump files.
    From reviewing the code of the memory leak detector code for
    detecting these ClassLoader leaks, it is evident that, whilst
    the detector waits for a period of time to allow application
    destroy processing to take place, it does not ensure that a GC
    cycle has been requested prior to the point it assumes that its
    WeakReference to the ClassLoader would be cleared.
    

Problem conclusion

  • A suitable request for GC was added into the memory leak
    detector code immediately prior to its check for leaking
    application ClassLoaders consistently causes it to report that
    there is no leak detected for either the application
    ClassLoader or the ClassLoader of its war.
    
    The fix for this APAR is currently targeted for inclusion in
    fix packs 9.0.0.2 and 8.5.5.11.
    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

    PI64266

  • 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

    2016-06-15

  • Closed date

    2016-09-20

  • Last modified date

    2016-09-20

  • 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:
16 October 2021