Troubleshooting performance monitoring statistics

Use this task to resolve inconsistencies between performance monitoring statistics for the enterprise bean counters MethodLevelCallCount and MessageCount when deploying message driven beans in a cluster environment.

About this task

This task addresses inconsistencies in performance monitoring statistics for message driven beans in a cluster environment. Sometimes the number of messages in a trace correspond with the Performance Monitoring Infrastructure (PMI)/Tivoli Performance Viewer (TPV) output statistics but not with the log message from the message driven bean. This arises because the MethodLevelCallCount enterprise bean counter has a different meaning for message driven beans than for other beans.

In general, in terms of PMI statistics collection, and with reference to the Enterprise JavaBeans (EJB) container, message delivery comprises the following steps:
  1. EJB container pre-invoke processing. This prepares the execution environment for message delivery.
  2. Removing the message from the queue and invoking the message driven bean method to process that message.
  3. EJB container post-invoke processing. This cleans up the execution environment for example, committing or rolling back the transaction started during pre-invoke processing.

If there are multiple servers or threads attempting to remove a message from the queue and deliver it to a message driven bean, at Step 2 a messaging service may discover that the queue is empty and there is nothing to deliver because another server or thread has already processed the message. If this happens, the message driven bean method is not called at Step 2 and therefore the MethodLevelCallCount does not correspond to the number of times a message is delivered to the message driven bean for processing. Instead, the MethodLevelCallCount indicates the number of times message delivery is attempted: the enterprise bean counter MessageCount indicates the number of successful deliveries to a message driven bean.

In a single server environment MethodLevelCallCount and MessageCount should be the same. However, in a multi-server environment (or an environment with multiple consumers), these counts can be different. If the difference is large, consider retuning your messaging system.

To identify and resolve problems that you think are related to WebSphere Messaging, you can use the standard WebSphere Application Server troubleshooting facilities. If you encounter a problem that you think might be related to WebSphere Messaging or to other message-driven beans issues, see the related links.




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Last updated: Sep 20, 2010 11:08:29 PM CDT
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