PK74018: WORKLOAD MANAGEMENT CALLBACK FAILURES RESULT IN HIGH CPU

Fixes are available

APAR status

Closed as program error.

Error description

Description:

There is a problem in the workload management (WLM) code path
that deals with selection callbacks in which we are not
properly removing items from the thread pool after they are
processed.  In certain setups this can cause no updates to be
processed, and depending on how many and what type of objects
are on the pool can lead to a high CPU utilization.

The scenario which discovered this had a very high client load
attempting to route to a cluster that was still in the process
of starting up.  Because the cluster is not up, this causes WLM
to enter a callback object into the thread pool to attempt
selections are regular intervals for a set time period to try to
find a target if new cluster data comes in.  Because of the
above problem, even after the maximum time limit we should wait
to do this callback, we were not correctly removing that
callback object from the pool, causing us to execute it
repeatedly.

Local fix

Problem summary

****************************************************************
* USERS AFFECTED:  All users of WebSphere Application Server   *
*                  V6.1 and V7.0                               *
****************************************************************
* PROBLEM DESCRIPTION: Workload management (WLM) callback      *
*                      failures result in high CPU             *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
There is a problem in the WLM code path that deals with
selection callbacks in which we are not properly removing items
from the thread pool after they are processed.  In certain
setups this can cause no updates to be processed, and depending
on how many and what type of objects are on the pool can lead to
a high CPU utilization.

The scenario which discovered this had a very high client load
attempting to route to a cluster that was still in the process
of starting up.  Because the cluster is not up, this causes WLM
to enter a callback object into the thread pool to attempt
selections are regular intervals for a set time period to try to
find a target if new cluster data comes in.  Because of the
above problem, even after the maximum time limit we should wait
to do this callback, we were not correctly removing that
callback object from the pool, causing us to execute it
repeatedly.

Problem conclusion

This APAR addresses the issue by ensuring the correct
comparisons and that the updates will be processed and
removed from the tree, which allows the tree to get cleaned
up and the callbacks to complete, which removes the high CPU
condition.

The fix for this APAR is currently targeted for inclusion in
fixpacks 6.1.0.23, 7.0.0.3.  Please refer to the Recommended
Updates page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PK74018
Reported component name
WEBSPHERE APP S
Reported component ID
5724J0800
Reported release
61W
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt
Submitted date
2008-10-17
Closed date
2008-11-06
Last modified date
2008-11-06

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WEBSPHERE APP S
Fixed component ID
5724J0800

Applicable component levels

R61A PSY
UP
R61H PSY
UP
R61I PSY
UP
R61P PSY
UP
R61S PSY
UP
R61W PSY
UP
R61Z PSY
UP
R700 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"6.1","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
29 December 2021

Tips

PK74018: WORKLOAD MANAGEMENT CALLBACK FAILURES RESULT IN HIGH CPU

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R61A PSY

R61H PSY

R61I PSY

R61P PSY

R61S PSY

R61W PSY

R61Z PSY

R700 PSY

Document Information

Share your feedback

Need support?