PQ84981: WEBSPHERE FOR Z/OS V5.0 DOES NOT HONOR A THROTTLE ON THE MESSAGE LISTENER PORT FOR MQ.

 A fix is available

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APAR status
Closed as program error.

Error description
WebSphere for z/OS v5.0 needs to honor a throttle on the
Message Listener Port that will prevent the WLM queue from
being overrun with message handlers.
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All users of WebSphere Application Server    *
*                 V5.0 for z/OS                                *
****************************************************************
* PROBLEM DESCRIPTION: A high quantity of JMS messages in a    *
*                      JMS destination for which an MDB is     *
*                      configured to listen to causes a large  *
*                      number of work requests to be queued    *
*                      in the WLM queue. The ability to        *
*                      process the requests in a timely        *
*                      fashion is reduced.                     *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When a considerably large number of JMS Messages are sent to a
JMS destination an MDB is listening to, the amount of work
requests generated exceeds the capacity to process those
requests in the Servant region. Messages are redelivered in some
instances, therefore aggravating the problem.
Problem conclusion
The amount of work requests generated by messages being sent to
a JMS destination is limited by means of a throttling mechanism.
This throttle uses the Maximum sessions property of the Listener
Port to control the number of work requests queued into the WLM
queue. It allows available resources in the Servant Region
to appropriately process the limited number of requests more
efficiently.

Please Note:

As a result of APAR PQ84981, for installations that are
exploiting Message Driven Beans (MDBs), a review of Message
Listener Port (MLP) MaxSession settings maybe required.
Previously, WebSphere Application Server V5.0 for z/OS only used
the MaxSession value to control the number of open sessions that
any given servant region would attempt to obtain for servicing
an MDB application configured to this MLP.  With the application
of this maintainence, the MaxSession setting now represents the
maximum concurrency level for MDB traffic configured to that
MLP.  As an example, previously, in a configuration that had an
MLP with MaxSession set at 5 with 3 servants, WebSphere
Application Server V5.0 for z/OS would have had a variable
maximum concurrency level of 15 simultaneous MDB dispatches.
After application, the maximum concurrency level is 5,
regardless of the number of servant regions.

The following publication was revised as a result
of APAR PQ84981:
________________________________________________________________
WebSphere Application Server V5 for z/OS
Messages and Codes
GA22-7915-00
________________________________________________________________
This APAR requires changes to documentation.

NOTE: Periodically, we refresh the documentation on our
Web site, so the changes might have been made before you
read this text. To access the latest on-line
documentation, go to the product library page at:

www.ibm.com/software/webservers/appserv/zos_os390/library.html

________________________________________________________________
Chapter 2, pg. 40 (new message)
BBOO0284I
STATISTICS GATHERING NOT ENABLED FOR <string>

Explanation: A display,work command was issued to display
statistics for request of type <string>.  However, statistics
are not currently being gathered for requests of type <string>.

User Response: If statistics are desired for requests of type
<string>, then enable statistics gathering by using the
f <server>,<string>stats command (e.g. "f bbos001,mdbstats,
enable").
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C2131E

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C2131F

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21320

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21321

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21322

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21323

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21324

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21325

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21326

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 3, pg. 125 (new message)
C9C21327

Explanation: IBM Internal Only
User Response: Contact the IBM Support Center.
________________________________________________________________
Chapter 1, pg. 4 (new message)
BBOJ0088I
MLP NAME  name  TIME  time  secs.

Explanation: This message is used to display MDB statistics.
User Response: None
________________________________________________________________
Chapter 1, pg. 4 (new message)
BBOJ0089I
 statistics header

Explanation: This message is used to display MDB statistics
header.
User Response: None
________________________________________________________________
Chapter 1, pg. 4 (new message)
BBOJ0090I
 statistics

Explanation: This message is used to display MDB statistics.
User Response: None
________________________________________________________________
Chapter 1, pg. 4 (new message)
BBOJ0091I
Duplicate Message Reference Count: count  MR: Message Reference

Explanation: This message is used to display MDB statistics.
User Response: None
________________________________________________________________
Chapter 1, pg. 4 (new message)
BBOJ0092I
NO ACTIVE LISTENER PORT,  command name  COMMAND IGNORED

Explanation: There are no Listener Ports for which to display
MDB statistics.
User Response: None
________________________________________________________________

APAR PQ84981 requires the following change to the InfoCenter. To
access the latest online documentation, go to the product
library page at:

www.ibm.com/software/webservers/appserv/zos_os390/library/

APAR PQ84981 provides the following new articles to the
InfoCenter:

 -"MDB Throttle Support"
 -"Configuring MDB Throttle Support"
 -"Best practices for debugging MDB throttle support"

APAR PQ84981 provides an update to the existing InfoCenter
articles:

 - "Using message-driven beans in applications"
 - "Administering WebSphere JMS support"
 - "Troubleshooting WebSphere Messaging"
 - "Tuning for J2EE applications"
 - "Listener port settings"

APAR PQ84981 is associated with SERVICE LEVEL W502009 of
WebSphere Application Server V5.0 for z/OS.
Temporary fix Comments
APAR information
APAR number PQ84981
Reported component name WEBSPHERE FOR Z
Reported component ID 5655I3500
Reported release 500
Status CLOSED PER
PE NoPE
HIPER YesHIPER
Special Attention NoSpecatt
Submitted date 2004-02-19
Closed date 2004-05-21
Last modified date 2004-06-17

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Modules/Macros
BBOUBINF          

Publications Referenced
GA22791500        

Fix information
Fixed component name WEBSPHERE FOR Z
Fixed component ID 5655I3500

Applicable component levels
R500 PSY UQ88747    UP04/05/27 P F405

  Fix is available
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Document Information


Current web document: swg1PQ84981.html
Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server for z/OS
Operating system(s):
Software version: 500
Software edition:
Reference #: PQ84981
IBM Group: Software Group
Modified date: Jun 17, 2004