Cycle detection and object memory usage?

[Jim Kleckner]

cycles:

I understand from the documentation that types with a finalizer method 
that participate in cycles can't be collected.

What is the best way to go about finding these cycles?
Googling gives a variety of methods none of which seem terribly 
mainstream for such a common problem.


Object memory usage:

Has anyone written a function to sweep out an object to discover how 
much memory it and all the objects it references is using?  This would 
be great for performance tuning.

Thanks.