I implemented something heavily based on that once¹, though no work has gone into optimizing much. It's not particularly state-of-the-art, but it's a good desig

I implemented something heavily based on that once¹, though no work has gone into optimizing much. It's not particularly state-of-the-art, but it's a good design for what it is. I'll probably use the quad-color strategy in my next incremental GC. Note that while Mike's is strictly non-copying/non-compacting (because of Lua's API) mine does copy between generations and compacts the oldest generation. This makes arena management simpler and faster. I think that's the only significant difference between my implementation and Mike's design. I suspect it's still a bit buggy, though it passes my test suite™. Non-trival GCs can be tricky. And to reiterate, it's not especially fast, because no work has gone into making it fast. (It's not slow either, because the design is good, but don't expect performance competitive with current production GCs².) 1. https://github.com/alpha123/yu https://github.com/alpha123/yu 2. Well, it probably smokes Ruby and Python, but those go solidly in the ‘toy GC’ category.