PI64266: MEMORY LEAK DETECTOR PRODUCING FALSE POSITIVE REPORTS

Fixes are available

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

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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":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.5","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
03 May 2022

Tips

PI64266: MEMORY LEAK DETECTOR PRODUCING FALSE POSITIVE REPORTS

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

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

Fixed component ID

Applicable component levels

R850 PSY

R900 PSY

Document Information

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