I fail to see how it's interesting to general HN population, but if you insist: you better replace jhat with Eclipse's memory analysis tool.

jhat is a wonderful tool that introduced me to memory analysis, but it fails on large memory dumps and has long initialization times.

Anyway, memory analysis is a wonderful thing which I'll surely lack if I'd move into C/C++ or dynamic languages (non-JVM hosted). It makes you deeply understand your program's memory consumption.