Is there a name for Ruby's garbage collecting strategy?
    I'm on a web forum and the topic of garbage collection came up. 
There's a claim that you can never make a "perfect" garbage collector.  In 
other words, there will always exist (pathological) conditions where your 
collection strategy will fail to find inaccessible objects.  At least, 
that's my best understanding of the claim and it strikes me as... false.  I 
can understand that the task is non-trivial but simply impossible?  Can 
that be right?
    Furthermore, according to some, Java (a friendly Ruby competitor) is 
incapable of collecting, specifically, circular references.  I was just 
wondering if Ruby had the same limitation?
    Thank you...