This topic applies only on the z/OS operating system.

Workload management for ASF message-driven beans that use WebSphere MQ as the messaging provider

Use workload management (WLM) classification and define unique service classes for different-priority work running in the same server.

Whenever you are running WebSphere® Application Server on z/OS, you must allow at least one servant for processing each service class. For more information about workload classification, see Classifying z/OS® workload.

Each listener port has one throttle that controls the rate at which differently-prioritized messages are queued as work records on the WLM queue.

When there is a backlog of messages on the WebSphere MQ queue for the message-driven bean, you want certain messages to be processed before others based on transaction class. However the RA listener selects messages from the WebSphere MQ queue and puts them on the WLM queues without considering transaction class. WLM prioritization does not occur while messages are browsed by the queue agent thread – prioritization occurs when work records are queued up.

To ensure that the WLM queue is loaded sufficiently to allow WLM prioritization, set the high threshold (that is, the value of the maximum sessions property of the listener port) higher than the baseline recommendation of "twice the combined number of worker threads in all the servants for the server ."

To control throttling, you need to determine the following values: These values can be estimated by using Performance Monitoring Information (PMI), other monitoring tools, or perhaps by a high-level understanding of how the message-driven bean fits into the general application flow of a specific server.
You can then adjust the baseline formula to set the listener port maximum sessions property to one of the following values: Too low a setting causes idle worker threads. Too high a setting can cause extra messages to build up on the WLM queue, but the extra messages should not be sufficient to overload the WLM queue and cause the server to fail.



Related concepts
[z/OS] The message-driven bean throttling mechanism on z/OS
[z/OS] MDB throttle settings for message-driven beans on z/OS
[z/OS] Connection factory settings for ASF message-driven beans that use WebSphere MQ as the messaging provider on z/OS
[z/OS] Messaging flow for ASF message-driven beans with WebSphere MQ as the messaging provider
Concept topic    

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Last updated: Oct 21, 2010 7:37:48 AM CDT
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