Hello,
i have find at this address (http://debug.martinleopold.com/) the plugin for insert in processing a debug mode but...the "debug" box in my Processing don't appears 
I have a version 2.1 of Processing program...is correct?
Thank for help me!
Have you tried asking this question at the Processing forum?
You'd probably get a better answer there.
Installation
Requires Processing 2.0 (Download / Processing.org)
So, you assume that you can use Processing 2.1. I wonder why.