PK09021: THE NUMBER OF"COM/IBM/WS/WEBCONTAINER/SRT/WEBAPPINVOKER" OBJECTSIS ALMOST DOUBLE THE NUMBER OF THE INVOCATION CACHE SETTING

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APAR status
Closed as program error.

Error description
In WSAS 5.X, Upon Analyisis of the HeapDump we notice the number
of"com/ibm/ws/webcontainer/srt/WebAppInvoker" objects grow over
a period of time, The number is almost double the number
 of the invocation cache setting.

Details : The default invocation cache setting is 50 for each
webcontainer thread and the deafult webcontainer thread pool is
50. so at any given point you should see no more than 2500
entries. but Analysis of Hepadumps, taken during Peak load
suggest that there are close to 5000 entires
One cache entry  loosely equates to one
" com/ibm/ws/webcontainer/srt/WebAppInvoker"  object

Here is the standard formula to calculate the cache entries

V 5.X

If the thread pool size is set to P and invocation cache size is
set to C, the total number of cached WebAppInvoker is
 (2 * P + 1) * C

V 4.X
The total number is (P + 1) * C


In V5, it approximately doubled the number of cached objects
comparing to V4 or calculated number.

Reason for increase in V5.X:

The reason of the increase is that, in V5, the number of request
processors created by transport is (2 * P + 1) and each
processor has an invocation cache of up to C cached objects.
.
This APAR also addresses distributed APAR 
PK05604
Local fix
no Work Around available at this time
Problem summary
****************************************************************
* USERS AFFECTED: All users of WebSphere Application Server    *
*                 V5.0 for z/OS                                *
****************************************************************
* PROBLEM DESCRIPTION: Analysis of a v5.0 HeapDump             *
*                      after a peak load run showed            *
*                      that there was a huge number of         *
*                      "com/ibm/ws/webcontainer/srt/           *
*                      WebAppInvoker" objects that grew over   *
*                      a period of time.                       *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
The default invocation cache setting is 50 for each
webcontainer thread and the default webcontainer thread pool is
50. So, at any given point you should see no more than 2500
entries but analysis of Heapdumps taken during peak load
suggest that there are close to 5000 entires.  One cache entry
equates to about one "com/ibm/ws/webcontainer/srt/WebAppInvoker"
object.  These cached objects are doubled which consumed more
memory than in v4.  The formula for v5, cached objects =
#threads * cache size was not held.
Problem conclusion
The code was modified to detach the invocation cache from the
SRPRequestProcessor. It is purely thread based so that only
the maximum thread number of caches will be created.  Now the
formula of cached objects = #threads * cache size holds.

APAR PK09021 is associated with SERVICE LEVEL W502032 of
WebSphere Application Server V5.0 for z/OS.
Temporary fix Comments
APAR information
APAR number PK09021
Reported component name WEBSPHERE FOR Z
Reported component ID 5655I3500
Reported release 500
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2005-07-18
Closed date 2005-07-25
Last modified date 2006-02-26

APAR is sysrouted FROM one or more of the following:
PK06649

APAR is sysrouted TO one or more of the following:

Modules/Macros
BBOUBINF          

Publications Referenced

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

Applicable component levels
R500 PSY UK05697    UP05/07/29 P F507

  Fix is available
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Document Information


Current web document: swg1PK09021.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 #: PK09021
IBM Group: Software Group
Modified date: Feb 26, 2006