Monday, June 18, 2012

EJB Calltime Monitoring

I wanted to give a brief illustration of RHQ's calltime monitoring feature by showing how it is used to collect EJB calltime statistics. The idea here is that I have an EJB application (in my example, I am using the RHQ Server itself as the monitored application!) and I want to see calltime statistics for the EJB method calls being made. For example, in my EJB application being monitored, I have many EJB Stateless Session beans (SLSBs). I want to see how my EJB SLSBs are behaving by looking at how many times my EJB SLSB methods are called and how efficient they are (that is, I want to see the maximum, minimum and average time each EJB SLSB method took).

So, first what I do is go to my EJB SLSB resources that are in inventory and I enable the "Method Invocation Time" calltime metric. You can do this on an individual EJB resource or you can do a bulk change of all your EJB's schedules by navigating to your EJB autogroup and changing the schedule in the autogroup's Schedules subtab:



At this point, the RHQ Agent will collect the information and send it up to the RHQ Server just like any other metric collection. Over time, I can now examine my EJB SLSB calltime statistics by traversing to my EJB resource's Calltime subtab:



I can even look at an aggregate view of all my EJBs via the EJB autogroup. In the RHQ GUI, you will see in the left hand tree all of my EJB SLSBs are children of the autogroup node "EJB3 Session Beans". If I select that autogroup node and navigate to its Calltime subtab, I can see all of the measurements for all of my EJB SLSBs:



Note that this calltime measurement collection feature is not specific to EJBs, or the JBossAS 4 plugin. This is a generic subsystem supported by any plugin that wants to enable this feature. If you want to write your own custom plugin that wants to monitor calltime-like statistics (say, for HTTP URL endpoints or any other type of infrastructure that has a "duration" type metric that can be collected) you can utilize the calltime subsystem to collect your information and let the RHQ Server store it and display it in this Calltime subtab for your resource.

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