[gclist] Age based promotion

[Simon Peyton-Jones]

David

> Supposing you keep two flavors of remembered set, one for those
> old objects modified to point to young (and hence likely to be
> modified again to point to different young) and the other for
> those objects promoted which happen to contain pointers to young?

Thanks for the algorithm you suggest.  By suggesting it, you imply that this
issue is not well covered in the literature, which confirms what
I thought.

> I don't think that transitive promotion is a good idea, since I can
> imagine (and I think I've seen) certain programming styles for which
> this would be a relatively disastrous policy.

Dave Ungar said this too.  Can either of you give some idea of what
sort of programs would behave badly?  The kind where old things are
modified often?

Simon