From: Hongli Lai <hongli@...99.net>
Date: 2008-10-30T05:56:18+09:00
Subject: [ruby-core:19617] Re: GC thought

Roger Pack wrote:
> Re: objectspace.each_object being bad--I think you could still have
> objectspace.each_object with a this patch--it would just have to
> synchronize with the GC every time it pulled the "next" object out of
> the objectspace--i.e. basically revert to a blocking GC, with the same
> drawbacks as those listed above.
> Cheers!

I actually have thought about aligning the heaps for fast lookup, as you 
suggested. But it's a bit hard to do that in practice. For example, the 
APIs for aligned memory allocation are not very portable.

As for implementing a concurrent garbage collector, you *need* to have 
implemented write barriers. There are many papers on garbage collection, 
and I've noticed that it's pretty much impossible to implement anything 
more advanced than a simple mark-and-sweep unless you have write barriers.