Fix (APAR):  PK28948

Status:  Fix

Release:  6.0.2.9,6.0.2.7,6.0.2.5

Operating System:  AIX,HP-UX,Linux,Linux pSeries,Linux Red Hat - pSeries,Solaris,Windows

Supersedes Fixes:  

CMVC Defect:  PK28948

Byte size of APAR:  38889

Date: 2006-10-11

Abstract:  High CPU if persistance is used for session management, more so with database persistence.

Description/symptom of problem:  
PK28948 resolves the following problem:

ERROR DESCRIPTION:                                              
In WAS6, whenever a request is made, the session manager updates
the last access time.  When session persistence is used, this   
can lead to some performance loss.                              
                                                                
In order to recover the performance, this APAR introduces a     
custom property which can disable the update of last access     
time. The name of the custom property is                        
OnlyCheckInCacheDuringPreInvoke.  By default the value is false,
which means websphere application server will continue to       
function as it was before the APAR was applied. Once this custom
property is set to true, session manager will no longer update  
the last access time when request is made.  However, if the     
session object is accessed by the request then the last access  
time will be updated as before.                                 

LOCAL FIX:                                                      

PROBLEM SUMMARY

USERS AFFECTED:
Users of session manager with persistence
in WebSphere Application Server version 6.

PROBLEM DESCRIPTION:
High CPU if persistance is used for
session management, more so with
database persistence.

RECOMMENDATION:
None

By default session manager updates the last access time when
database persistence is configured and this leads to high CPU
usage.

PROBLEM CONCLUSION:                                             
A web container custom property,                                
OnlyCheckInCacheDuringPreInvoke,                                
is introduced to disable session manager to update the last     
access time everytime a request is initiated.                   
                                                                
This APAR will be included in fixpacks 6.0.2.17 and 6.1.0.6.    
Please refer to the recommended updates page for delivery       
information:                                                    
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980   

Directions to apply fix:  NOTE: Choose the:
1) Release the fix applies to
2) The Editions that apply
3) Delete the Editions & Methods that do not apply and this Note

Fix applies to Editions:
Release 6.0
_x_ Application Server (Express or BASE)
__ Network Deployment (ND)
__ WebSphere Business Integration Server Foundation (WBISF)
__ Edge Components
__ Developer
__ Extended Deployment (XD)

Install Fix to:
Method:
_x_ Application Server Nodes
__ Deployment Manager Nodes
__ Both

NOTE:
The user must:
* Have Administrative rights in Windows, or be the Actual Root User in a UNIX environments.
* Logged in with the same authority level when unpacking a fix, fix pack or refresh pack.
* Be at V6.0.2.2 or newer of the Update Installer. This can be checked by reviewing the level of the Update Installer in file <was_root>/updateinstaller/version.txt.

The Update Installer can be downloaded from the following link:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg21205991

For detailed instructions to Extract the Update Installer see the following Technote:
http://www-1.ibm.com/support/docview.wss?rs=180&uid=swg21205400

1) Copy PKxxxxx.pak file directly to the maintenance directory

2) Shutdown WebSphere
Manually execute setupCmdLine.bat in Windows or . ./setupCmdLine.sh in Unix from the WebSphere instance that maintenance is being applied to.

3) Launch Update Installer

4) Enter the installation location of the WebSphere product you want to update.

5) Select the "Install maintenance package" operation.

6) Enter the file name of the maintenance package to install (PKxxxxx.pak file which was copied in the maintenance directory).

7) Install the maintenance package.

8) Restart WebSphere

Directions to remove fix:  NOTE:
* The user must have Administrative rights in Windows, or be the Actual Root User in a UNIX environments.
* FIXES MUST BE REMOVED IN THE ORDER THEY WERE APPLIED
* DO NOT REMOVE A FIX UNLESS ALL FIXES APPLIED AFTER IT HAVE FIRST BEEN REMOVED
* YOU MAY REAPPLY ANY REMOVED FIX

Example: If your system has fix1, fix2, and fix3 applied in that order and fix2 is to be removed, fix3 must be removed first, fix2 removed, and fix3 re-applied.

1) Shutdown WebSphere
Manually execute setupCmdLine.bat in Windows or . ./setupCmdLine.sh in Unix from the WebSphere instance that uninstall is being run against.

2) Start Update Installer

3) Enter the installation location of the WebSphere product you want to remove the fix.

4) Select  "Uninstall maintenance package" operation.

5) Enter the file name of the maintenance package to uninstall (PKxxxxx.pak).

6) UnInstall maintenance package.

7) Restart WebSphere

Directions to re-apply fix:  1) Shutdown WebSphere.

2) Follow the Fix instructions to apply the fix.

3) Restart WebSphere.

Additional Information:  Applies to release 6.0.2.5 to 6.0.2.11