I know there are still some bugs and corner cases that need to be worked out, but I am really impressed with how well this is working. I would think that moving from a traditional single-threaded mark and sweep to a moving, concurrent GC would be a very involved change. Requiring a rewrite of many components. But it looks like it was “just” plugging into the MPS API. I realize that library does several things to make this easier, like supporting pinning and weak references, but I am still impressed.