PQ90664: THE MDB PROCESSING BEHAVIOR IS BEING CHANGED TO ENABLE THROTTLE AFTER (X+1) MESSAGES ARE RECEIVED WHERE MAXSESSIONS=X. | |||||||||||||||||||||||||||||||||||||||||||
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![]() APAR status Closed as program error. Error description W502009 level of WebSphere for z/OS added code to honor a throttle on the message listener port. The maxsessions setting for the message listener port controls the number of messages accepted before the code blocks. The blocking continues until the messages received are processed by the servant. . In the specific case where there are more than one message listener ports all set to maxsessions=1, the code blocks as soon as 1 message is received. The code is being changed so that it blocks after it exceeds the maxsessions limit. Currently it is set to block as soon as the messages equal the maxsessions value. The change will give a degree of parallelism in these specific cases.Local fix Problem summary **************************************************************** * USERS AFFECTED: All users of WebSphere Application Server * * V5.0 for z/OS * **************************************************************** * PROBLEM DESCRIPTION: Different behaviors are exposed for * * Scalable Messaging Support (Plan A) and * * Generic Messaging Support (Plan B) when * * multiple MDBs are listening to the same * * queue by using independent listener * * ports with maxSession setting of 1 and * * each MDB has a message selector. * **************************************************************** * RECOMMENDATION: * **************************************************************** When multiple MDBs are listening to the same queue by using independent listener ports with maxSession setting of 1 and each MDB has a message selector, messages from the queue are delivered to the corresponding MDB. The throttle support blocks message distribution when a messaging work request is enqueued for every single message in the queue. This behavior differs from the Generic Messaging (Plan B) where message distribution is only blocked when a message is to be delivered to an MDB that is already processing a message. For example, for a message sequence of A,B,A,C messages would normally be delivered to MDB_A and MDB_B before blocking. For Scalable Messaging, the message is delivered to just MDB_A, the throttle waits for message processing completion to continue delivery to MDB_B and then MDB_C.Problem conclusion The MDB Throttle was modified to block only when the listener port maxSession is exceeded. This allows messages to be delivered to several MDBs in a semi-concurrent manner as the Generic Messaging Support (Plan B). APAR PQ90664 is associated with SERVICE LEVEL W502014 of WebSphere Application Server V5.0 for z/OS.Temporary fix Comments
APAR is sysrouted FROM one or more of the following: APAR is sysrouted TO one or more of the following: PQ91092 Modules/Macros
Publications Referenced
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Document Information |
Current web document: swg1PQ90664.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 #: PQ90664
IBM Group: Software Group
Modified date: Sep 3, 2004
(C) Copyright IBM Corporation 2000, 2009. All Rights Reserved.