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This document applies only to the following language
version(s):
English |
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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. |
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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. |
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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.
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Cross Reference information |
Segment |
Product |
Component |
Platform |
Version |
Edition |
Application Servers |
WebSphere Application Server |
Programming Model Extensions (PME) |
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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 |
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