Basic mark & sweep is simple to understand and implement. See e.g. https://code.google.com/p/tinypy/source/browse/trunk/tinypy/gc.c https://code.google.com/p/ti

Basic mark & sweep is simple to understand and implement. See e.g. https://code.google.com/p/tinypy/source/browse/trunk/tinypy/gc.c https://code.google.com/p/tinypy/source/browse/trunk/tinypy/... - 136 lines of C code in tinypy. You'll find more examples if you look at other small implementations. But you also want fast, at which point you have to accept that fast gc == complicated and tightly coupled to the implementation details (object layout, type/debug info). There is no pluggable GC. Conservative GCs (like Boehm GC) come the closest, but they have significant drawbacks (they blindly scan all of memory and can't tell a difference between a pointer and a random number that looks like a pointer, which means scanning&marking phase take longer and they keep objects that could have been freed, which is especially a problem on 32bits, where it's more likely that a random number points inside GC-managed heap).