Recycler. To be clear, http://trout.me.uk/gc/recycler-overview.pdf http://trout.me.uk/gc/recycler-overview.pdf There's also a paper with the full algorithm in

Recycler. To be clear, http://trout.me.uk/gc/recycler-overview.pdf http://trout.me.uk/gc/recycler-overview.pdf There's also a paper with the full algorithm in that directory. It's how Nim's ORC collector works. (note that yes, I know, this is for collection, not cycle detection in general, but it's also brilliant and works)