I intend to use play web framework with AciveJDBC for persistence. The issue with active JDBC is that it requires instrumentation. My question is ,
Will I need to do a restart on the server to see the changes made on classes that need instrumentation?
as a disclaimer, I never tried what you said. But from my knowledge on how Play works, this will depend on your integration of ActiveJDBC with Play.
As far as I know, there is no existing module for that integration. This means you will need to create something to plug your model (ActiveJDBC - based) with the Play Model. Similar to what the Siena plugin does, for example.
Once done, with no extra changes Play will only recompile the Java class, using the Eclipse compiler, but it won't generate any instrumentation. For that instrumentation to happen you will probably need to tweak the recompile process so it also generates the instrumentation.
So, short answer, by default instrumentation won't work.
A somehow related question: do you really need ActiveJDBC? What does it offer that JPA/Hibernate (the default in Play) won't? I understand the appealing of an "Active Record" behavior, but even in the Ruby community there are some complains on its "magic". Are you sure JPA is not good enough? Using it would save you time and headaches when working with Play, and Hibernate a big team and lot of experience developing ORM, which makes it a great tool...