Fix (APAR):  PK25804

Status:  Fix

Release:  6.0.2.9, 6.0.2.11

Operating System:  AIX,HP-UX,i5/OS,Linux,Linux pSeries,Linux Red Hat - pSeries,Linux zSeries,OS/390,OS/400,Solaris,Windows,z/OS

Supersedes Fixes:  PK23436

CMVC Defect:  PK25804

Byte size of APAR:  16991 and 16993

Date: 2006-06-21

Abstract:  Deadlock in Dynamic cache when performing a batch operation.

Description/symptom of problem:  
PK25804 resolves the following problem:

ERROR DESCRIPTION:                                              
 Deadlock in Dynamic cache when processing the batch operations 
                                                                
 WebSphere Version(Base & ND) 6.0.2.9, 6.0.2.11                          
                                                                
  After running portal for a couple of hours portal experience  
dead lock in dynacache code.This issue is seen while Stress test
of Portal application on WebSphere Version 6.0.2.9.             

LOCAL FIX:                                                      
Test fix was provided.                                          

PROBLEM SUMMARY

USERS AFFECTED:
WebSphere Application Sever version 6 users
using DistributedMap.

PROBLEM DESCRIPTION:
Deadlock in Dynamic cache when
performing a batch operation.

RECOMMENDATION:
None

The deadlock occurs under the following scenarios:
1. One thread: process clear command, it locks Cache A. It
processes the batch operations. When it tries to trim the
Cache B, it locks Cache B.
2. Another thread: process clear command, it locks Cache B. It
processes the batch operations. When it tries to trim Cache A,
it locks Cache A.

PROBLEM CONCLUSION:                                             
The problem is fixed by removing trim cache logic from the      
batch operations. The trim cache operations will be performed   
after a wakeup thread removes the entries whose time limit has  
expired. This way will prevent the deadlock problem on cache    
instances.                                                      
The code is modified to move the process of trim cache for      
each cache instances in BatchUpdate daemon to TimeLimit         
daemon.                                                         
The TimeLimit daemon is triggered when it is time to check      
whether the entries in cache buffer expire or not.              
After the code checks the expiration, it starts trimming each   
cache instance if buffer size of the cache instance is over     
the cache size.                                                 
                                                                
The fix for this APAR is currently targeted for inclusion in    
fixpack 6.0.2.13 and 6.1.0.1.                                   
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
__ Application Server (Express or BASE)
__ Network Deployment (ND)
__ WebSphere Business Integration Server Foundation (WBISF)
__ Edge Components
__ Developer
__ Extended Deployment (XD)

Install Fix to:
Method:
__ 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:  
To install the fix:
   For WAS 6.0.2.9 and 6.0.2.11, use 6.0.2.9-WS-WAS-IFPK25804-CF9.pak or 6.0.2.9-11-WS-WAS-IFPK25804.pak
   For WAS 6.0.2.11, use 6.0.2.9-11-WS-WAS-IFPK25804.pak