Scheduler, upgrading from 5.0.1 to 5.0.2, introduces the lease manager.
 Technote (troubleshooting)
 
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Problem(Abstract)
Many TaskPending Exceptions occur as a result of task collisions in a clustered Scheduler environment on WebSphere Application Server Enterprise Edition V5.0.1.
 
Cause
There was no lease manager in V5.0.1 which allowed tasks to run concurrently in clustered scheduler environments causing a high number of database collisions. The lease manager was added to V5.0.2 to address this problem.
 
Resolving the problem
The scheduler in V5.0.2 makes use of a lease manager to decrease the amount of contention between clustered scheduler instances. After upgrading to V5.0.2, you must recreate the Scheduler tables using the new DDL to enable the lease manager. This is done by either dropping the entire set of scheduler tables and re-running the scheduler ddl, or by editing the ddl so it only creates the new lease manager tables.


The two lease manager tables are <table_prefix>LMGR and <table_prefix>LMPR. They both must be in the same schema as the TASK and TREG tables. Below is sample output of the db2 list tables command from a test machine.


Table/View Schema Type Creation time
---------------- ------------- ----- --------------------------
SCHED_LMGR DADHANIA T 2004-11-29-15.22.27.944002
SCHED_LMPR DADHANIA T 2004-11-29-15.22.28.245002
SCHED_TASK DADHANIA T 2004-11-29-15.22.27.063001
SCHED_TREG DADHANIA T 2004-11-29-15.22.27.674001


Use the db2 list tables command on your database. If the LMGR and LMPR tables do not exist, it will be necessary to recreate the Scheduler tables using the instructions below.

Recreating Scheduler tables

For details about the lease manager and clustered scheduler toplogies, see the Scheduler Planning and Administration Guide.

 
 
Cross Reference information
Segment Product Component Platform Version Edition
Application Servers WebSphere Application Server Programming Model Extensions (PME) 5.x Enterprise
Application Servers WebSphere Application Server Enterprise PME Admin Console AIX, HP-UX, Linux, Multi-Platform, Solaris, Windows 5.0 Enterprise
Application Servers Runtimes for Java Technology Java SDK
 
 


Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server > Programming Model Extensions (PME)
Operating system(s): Windows
Software version: 5.0
Software edition:
Reference #: 1195651
IBM Group: Software Group
Modified date: Jan 12, 2005