Non-parallel version of GC

Simon Marlow marlowsd at
Tue Aug 13 12:35:54 CEST 2013

On 10/08/13 00:58, Edward Z. Yang wrote:

> How would people feel about an alternate GC implementation in GHC which
> is not parallel?  A GC like this would be simpler to understand, maybe a
> little faster when parallel collection is not being used, and (most
> importantly for my case) easier to extend with interesting features.
> In particular, this implementation would not have gen_workspace or
> gc_thread; these would either be unnecessary or folded directly into the
> actual generation object.

 From my point of view I'd like such a thing to be as separate as 
possible from the rest of the GC code.  However it might be hard to do 
that - you mentioned modifying the generation structure, for example.

As with most things in the RTS, the GC is "exactly as modular as it 
needs to be right now", which in practice means "not quite modular 
enough for what I want to do next" :-)  So your first step might be to 
abstract some things so that the two GCs can coexist peacefully.

But perhaps there's another way to achieve your goals - what are the 
interesting features you want to add?


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