Troubleshoot performance monitoring statistics


 

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Use this page to resolve inconsistencies between performance monitoring statistics for the enterprise bean counters...

...when deploying message driven beans in a cluster environment.

Sometimes the number of messages in a trace correspond with the PMI and TPV output statistics but not with the log message from the MDB. This arises because the bean counter...

MethodLevelCallCount

...has a different meaning for MDBs than for other beans.

In general, in terms of PMI statistics collection, and with reference to the EJB container, message delivery comprises the following steps:

  1. EJB container pre-invoke processing to prepare the execution environment for message delivery.

  2. Remove the message from the queue and invoking the MDB method to process that message.

  3. EJB container post-invoke processing to clean up the execution environment by committing or rolling back transactions 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 MDB, at Step 2 a messaging service might 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 MDB 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 MDB 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 MDB.

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 the messaging system.

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

 

Related tasks

Troubleshooting message-driven beans
Troubleshooting messaging

 

Related

Enterprise bean counters