MRI has had a variety of memory leaks. I did an extensive search for the memory leaks on god, which you can read about here: http://groups.google.com/group/god-rb/browse_thread/thread/0.... I've verified that it's not an object referencing issue (which you can also read about in that link). Something in the threading code of MRI appears to be at fault, but I haven't had time to track that down yet.