Dynamic Instrumentation - general query

[David Richards]

We are running Wily 9.0.6 in our POC environment at present and it is our first real look at Dynamic Instrumentation.
AIX, Websphere 7, JRE 1.6.0 IBM AIX build pap6460sr7ifx-20100220_01 (SR7)

Does the group have any thoughts about utilising this powerful feature ? Any best practices, or things to avoid etc ?

Has running DI ever caused stability issues with the instrumented JVM ?
We have managed to generate a "java.lang.IncompatibleClassChangeError" exception on one of our applicartions.

Thanks for any help

[WarrenPage]

Hey Dave,

We were involved in the beta for that and it seemed to work ok when we used it. I had one JVM get an error (which I cant remember now). I think I found it a little time consuming having to skip down the class tree instrumenting each level at a time. It would have been nice if it could scan down and auto-instrument methods taking more than x ms.

Cant say we use it since we upgraded. We wouldn't turn it on by default though we don't do that much instrumentation as a rule anyway.

[Haruhiko Davis]

DI is certainly a powerful feature.
It can be leveraged by any user of Introscope as a means of creating custom PBDs without the complexity of knowing how to use tools like ProbeBuilder and YATT. I can see developers using the functionality to create temporary or permanent PBDs for testing and production.

That being said, I would disable DI for your production agent for the same reasons we disable any sort dynamic monitoring. The overhead could be significant to your apps, so test it thoroughly.

-Hiko