How to Make a Garbage Collector Work in Parallel

Making a garbage collector work in parallel by itself is not terribly difficult. There are lots of papers about how to do it. So copying garbage collection you can just have a work queue for example. But the way that the GHC garbage collector works, well we use this block idea that the whole thing is divided into blocks of memory. Using blocks gives you a slightly better granularity at the expense of some parallelism.