Bytecode Instrumentation

Hello all, I want to extract the information of my code during the runtime of my program. The information can be anything like how, when and how many times a particular function is called or at general level what functions are defined in the .class file of the code and every such thing.
How can I do this? What libraries are defined for this purpose?

Crossposting is like separately asking 10 of your friends if you can have 10 dollars to buy lunch.

Crossposted: Bytecode Instrumentation

Sounds like profiling.
Which should give you a term to Google for.