PK12776: MDB LISTENER PORT MAY HANG WHEN A STOP IS ISSUED FOR IT WHILE PROCESSING MDB WORKLOAD IN WEBSPHERE FOR Z/OS V5.0.

 A fix is available

Obtain the fix for this APAR



APAR status
Closed as program error.

Error description
When the stop command is issued to the MDB Listener Port while
MDB workload is processing the listener port hangs and cannot be
restarted. This happens when the MDB throttle is blocking
message browsing because of a backlog of messages on the MDB
queue.This apar will address this problem.
.
MDB processing stops after after ListenerPort stop() command
followed by a ListenerPort start() command performed via the
Administrative Console or wsadmin scriptingin a server with
multiple ListenerPorts defined.
.
The problem will occur on another ListenerPort besides the one
on which the start() command was most recently issued.
.
When MDB processing stops, one can expect a backlog of messages
to build up on the MDB queue, (or for the topic in the case of
an MDB mapped to a topic via a durable subscription).
.
This is an additional symptom of this apar.
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All users of WebSphere Application Server    *
*                 V5.0 for z/OS                                *
****************************************************************
* PROBLEM DESCRIPTION: ListenerPort stop() command hangs when  *
*                      issued from Administrative Console or   *
*                      the wsadmin scripting environment.      *
*                                                              *
*                      Also, MDB processing stops after a      *
*                      ListenerPort stop() command followed    *
*                      by a ListenerPort start() command is    *
*                      performed via the Administrative        *
*                      Console or wsadmin scripting, on a      *
*                      server with multiple ListenerPorts      *
*                      defined.                                *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When the MDB throttle is blocking the QueueAgentThread from
browsing for messages in the controller at the moment that the
ListenerPort stop() command is issued, the stop() hangs.  This
is because the stop() first incorrectly tears down the
ListenerPort infrastructure which will allow the MDB throttle
to release this QueueAgentThread upon completion of message
dispatch.  However, due to locking mechanisms the stop() can
not complete until the QueueAgentThread is released, so it will
simply hang.

For the 2nd problem:

Users with multiple ListenerPorts defined for a given server
(under ApplicationServers -> <server> -> Message Listener
Service -> Listener Ports )
experience a stop of MDB processing on MDBs associated with one
or more ListenerPorts.  This happens after some series of
ListenerPort commands including a stop() and a start(), not
necessarily on the same ListenerPort.  The problem will
occur on another ListenerPort besides the one on which the
start() command was most recently issued.

When MDB processing stops, one can expect a backlog of messages
to build up on the MDB queue, (or for the topic in the case of
an MDB mapped to a topic via a durable subscription).
Problem conclusion
ListenerPort stop() processing was changed to release the
throttle and the QueueAgentThread immediately so that
ListenerPort processing can complete.  In addition, the throttle
function is disabled so it can not block the QueueAgentThread
again.  In its place, new messages for this ListenerPort browsed
before the ListenerPort is completely shutdown will simply be
ignored (left on the queue).  Also, ListenerPort stop() was
fixed to avoid the problem with a later ListenerPort start()
command.

APAR PK12776 requires changes to documentation.

The following publication was revised as a result
of APAR PK12776:
________________________________________________________________
WebSphere Application Server V5.0 for z/OS
Messages and Codes
GA22-7915-00
________________________________________________________________

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 01, pg. 005 (new message)
BBOJ0097=BBOJ0097E MDB FAILURE: {0}, IN CLASS: {1}, IN METHOD:
{2}
Explanation: This message is intended as a generic serious error
message
for MDB error conditions that don't require their own distinct
error messages.
User Response:  If the problem persists, contact the IBM support
center.
________________________________________________________________

APAR PK12776 is associated with SERVICE LEVEL W502035 of
WebSphere Application Server V5.0 for z/OS.
Temporary fix Comments
APAR information
APAR number PK12776
Reported component name WEBSPHERE FOR Z
Reported component ID 5655I3500
Reported release 500
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Special Attention NoSpecatt
Submitted date 2005-09-30
Closed date 2005-10-21
Last modified date 2005-11-03

APAR is sysrouted FROM one or more of the following:
PK12773

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 UK08352    UP05/10/27 P F510

  Fix is available
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Document Information


Current web document: swg1PK12776.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 #: PK12776
IBM Group: Software Group
Modified date: Nov 3, 2005