Fix (APAR):  PM94437

Status:  Fix

Release:  8.0.0.7

Operating System:  AIX,HP-UX,IBM i,Linux,Mac OS,Solaris,Windows,z/OS

Supersedes Fixes:  

CMVC Defect:  xxxxxx

Byte size of APAR:  306720

Date: 2013-12-13

Abstract:  minimize the number of threads that wait on the ldap context pool creation after ldap failure

Description/symptom of problem:  
PM94437 resolves the following problem:

ERROR DESCRIPTION:                                              
When Ldap connection fails, VMM discards all the old contexts   
from the context pool and recreates a new pool. While this new  
pool is being created, all threads requesting access to Ldap    
are put in a 'wait' state. This APAR, minimizes the number of   
threads that wait on the Ldap Context pool creation to a user   
configured number.                                              

LOCAL FIX:                                                      
NONE                                                            

PROBLEM SUMMARY

USERS AFFECTED:
 All users of IBM WebSphere Application
Server

PROBLEM DESCRIPTION:
When an LDAP server goes down, all
threads trying to communicate with
the LDAP get blocked until the read
times out.

RECOMMENDATION:
None

When an LDAP Server goes down, any new thread that tries to
read from the server gets an exception. Virtual Member manager
(VMM) then tries to recreate the LDAP Context Pool and during
this creation all incoming threads are blocked. If a
connection cannot be made for 120 seconds an exception is
thrown and the threads are able to complete their processing.
All requesting threads are, however, blocked for the duration
until the exception is thown.

PROBLEM CONCLUSION:                                             
The code was modified to ensure that all threads are not        
blocked during this context pool recreation. You can            
configure if you want to minimize the number of threads         
blocked and also configure the exact number of threads blocked  
with the help of custom properties                              
"minimizeContextPoolThreadBlock" and "maxThreadsToBlock". By    
default these values are "true" and "5". You can also           
customize to trace the bind timeout with a custom property      
named "bindTimeout".                                            
                                                                
In order to set these properties, use the following commands:   
                                                                
$AdminTask setIdMgrCustomProperty {-id <LDAP_repos_ID> -name    
minimizeContextPoolThreadBlock -value true}                     
                                                                
$AdminTask setIdMgrCustomProperty {-id <LDAP_repos_ID> -name    
maxThreadsToBlock -value 5}                                     
                                                                
$AdminTask setIdMgrCustomProperty {-id <LDAP_repos_ID> -name    
bindTimeout -value <millseconds>}                               
                                                                
Here "LDAP_repos_ID" is the repository id of the LDAP           
configured in VMM.                                              
"millseconds" is to track the count of "quick" binds.  Dump     
the updated statistic to the log.                               
                                                                
Also save the configuration after running the previous command  
using:                                                          
                                                                
$AdminConfig save                                               
                                                                
The fix for this APAR is currently targeted for inclusion in    
fix packs 7.0.0.31, 8.0.0.8 and 8.5.5.2.  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: Mark with an X the:
1) Release the fix applies to
2) The Editions that apply
3) And then DELETE THIS NOTE

Fix applies to Editions:
Release 8.0
_X_ Application Server (Express or BASE)
_X_ Network Deployment (ND)
__ Edge Components
__ Developer

Install Fix to all WebSphere installations unless special instructions are included below.

Special Instructions: None

NOTE:
The user must:
* Logged in with the same authority level when unpacking a fix, fix pack or refresh pack.
* Be at V1.4.3 or newer of the Installation Manager. Certain iFixes may require a newer version of the Installation Manager and the Installation Manager will inform you during the installation process if a newer version is required.

The IBM Information Center can provide details, if needed, on the use of the Installation Manager to apply the iFixes.
http://publib.boulder.ibm.com/infocenter/install/v1r4/index.jsp.  Shutdown WebSphere Application Server before applying the iFixes.  Restart WebSphere Application Server after applying the iFixes.

Directions to remove fix:  

The IBM Information Center can provide details, if needed, on the use of the Installation Manager to remove the iFixes.
http://publib.boulder.ibm.com/infocenter/install/v1r4/index.jsp.  Shutdown WebSphere Application Server before removing the iFixes.  Restart WebSphere Application Server after removing the iFixes.

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

2) Follow the Fix instructions to apply the fix.

3) Restart WebSphere Application Server.



Additional Information: