Transitioning to a type aware Garbage Collector

[Pragma]

Sean Kelly wrote:
> Paul Findlay wrote:
>> Walter Bright wrote:
>>> To improve GC performance, we need to transition to a GC that is 
>>> aware of the types of what it is allocating.
>> Does this mean the D garbage collector will be an exact (or precise) 
>> garbage collector?
> 
> If a block contains pointers then the entire block will still be scanned 
> instead of just the pointers in that block, so It will still be a 
> conservative collector but with fewer false positives.  I think this 
> could be changed so that just the pointers were scanned, but there would 
> likely be a noticeable performance hit for doing so. 


I was going to say: it sounds an awful lot like Walter is going to have the GC  stamp each allocated block (or its 
corresponding record) with a field that amounts to "bool containsPointers".  I'm all for it.  Especially since the 
majority of allocations and re-allocations in a typical D program are for strings, images and other non-pointer related 
data.  This simple change will amount to much smaller GC pauses, especially in the video games department.

 > If false positives
 > are still a concern (and I'm not convinced they will be), a better
 > approach may be to pursue a different GC design such as the CBGC
 > mentioned yesterday.

I haven't had a chance to read the paper myself, but the abstract left me with the impression that it's a good 
middle-of-the road approach to things.

Just an aside here: I keep reading that as "CBGB".

-- 
- EricAnderton at yahoo