Bytecode Instrumentation

| 2004 JavaOne

Conference | Session 3042 Copyright Hewlett Packard Co., 2004.

Dynamic BCI while program is running

Modify the selected method

•

Monitoring thread periodically wakes up and calls:

─ MyAgent.update()

Select hot class-method to instrument

─ MyTransformer.mytransform()

Add method we want to call to the Constant Pool

– MyTransformer.traceMethod()

Modify the bytecode of the hot method

Update the max stack value

Reset the Constant Pool

Create new class file

inst.redefineClasses(class, bytecodes)