I accidentally zapped this too much but let it ride as they say.

When I was spending a lot of time in matz's Ruby source code, debugging a Ruby vm I was maintaining embedded in a C thread, I got exposed to garbage collection for the first time. Back then, Ruby's gc was pretty premitive, it was a basic mark-and-sweep implementation if I didn't misunderstand it. This was before ruby 2.0 which already began to move away from naive tracing collection, and now they're doing tri-coloring like most GCs.