PK16552: MEMORY LEAK IN INVOCATION CACHE 06/01/05 PTF PECHANGE

 A fix is available

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APAR status
Closed as program error.

Error description
A memory leak has been found in the Invocation Cache which
leads to an OutOfMemory situation.

From the heapdump analysis it has been found that total number
of com/ibm/ws/webcontainer/srt/WebAppInvoker live objects are
more than expected. Expected maximum number of these objects is
as calculated as per below:

If,
P = Thread pool Size
C = invocation cache size

Then, the max number of Cached WebAppInvoker objects should be
the following:
(2 * P + 1) * C
Local fix
Setting the invocation cache size to zero will disable
invocation cache functionality, and therefore eliminate the
caching of WebAppInvoker objects. This can be set as follows:
(1) In the administrative console, click the Application Server.
(2) Click "Process Definition" under "Additional Properties".
(3) Click the "Java Virtual Machine" under "Additional
Properties".
(4) Add the following argument in the Generic JVM arguments:
 -DinvocationCacheSize=0
(5) Click Apply to ensure that the changes are saved.
(6) Stop and restart the application server.
Problem summary
****************************************************************
* USERS AFFECTED: All users of WebSphere Application Server    *
*                 V5.0 for z/OS                                *
****************************************************************
* PROBLEM DESCRIPTION: Invocation cache causes a memory leak   *
*                      and OutofMemory exception.              *
*                      From the heapdump analysis, it was      *
*                      found that the total number of          *
*                      com/ibm/ws/webcontainer/srt/            *
*                      WebAppInvoker live objects was          *
*                      more than expected.                     *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
Invocation caches are not released when associated transport
threads are being destroyed.  Hidden handles that hold up
InvocationCache objects prevent JVM garbage collecting of an
InvocationCache instance and its cached objects when a thread
is being destroyed.
Problem conclusion
The code was modified to remove hidden handles that hold up
InvocationCache.   The fix also adds a thread pool listener
that monitors thread activities within the pool. When a thread
is being destroyed its invocation cache will be invalidated and
released thus preventing memory leaks from invocation cache
instances.

APAR PK16552 is associated with SERVICE LEVEL W502038 of
WebSphere Application Server V5.0 for z/OS.
Temporary fix Comments
APAR information
APAR number PK16552
Reported component name WEBSPHERE FOR Z
Reported component ID 5655I3500
Reported release 500
Status CLOSED PER
PE YesPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2005-12-11
Closed date 2006-01-23
Last modified date 2006-02-02

APAR is sysrouted FROM one or more of the following:
PK12027

APAR is sysrouted TO one or more of the following:
PK17423

Modules/Macros
BBOUBINF          

Publications Referenced

Fix information
Fixed component name WEBSPHERE FOR Z
Fixed component ID 5655I3500

Applicable component levels
R500 PSY UK11044    UP06/01/27 P F601 

  Fix is available
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Document Information


Current web document: swg1PK16552.html
Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server for z/OS
Operating system(s):
Software version: 500
Software edition:
Reference #: PK16552
IBM Group: Software Group
Modified date: Feb 2, 2006