PQ90656; 5.0.2.6: Scheduler tasks do not execute
concurrently in 5.0.2 using DB2
Downloadable files
Abstract
In incorrout with WebSphere Enterprise V5. Scheduler tasks
do not run concurrently due to database locking problem.
Download Description
PQ90656 resolves the following problem:
ERROR DESCRIPTION:
Using the Scheduler Service in WebSphere Application V5 Enterprise
Edition, when multiple tasks are scheduled to run at the same time, it may
be observed that the tasks will only run sequentially and not
concurrently.
This occurs when DB2 V7 is used for the Scheduler database table. The
Scheduler poll daemon is blocked by an update to an index value by the
currently executing task. Because of this, new tasks cannot run until the
currently executing task is completed.
PROBLEM SUMMARY:
USERS AFFECTED:
All WebSphere Enterprise 5.0 Scheduler users using DB2
PROBLEM DESCRIPTION:
Scheduler tasks do not execute concurrently in 5.0.2 using DB2
RECOMMENDATION:
Apply intermediate fix PQ90656 to 5.0.2.
The Scheduler poll daemon will block when any scheduled tasks are
executing and the scheduler is configured to use DB2 as a backend
database. This will result in each task running serially instead of
concurrently. This behavior is seen predominantly when tasks run for a
long period of time.
PROBLEM CONCLUSION:
The Scheduler has been changed such that the poll daemon will now read
records using TRANSACTION_READ_UNCOMMITTED isolation level. In addition,
customers must use the DB2 setting "DB2_RR_TO_RS=Yes" to take advantage of
this fix.
Prerequisites
Please download the UpdateInstaller below to install this fix.