Memory Management in D: Request for Comment

[dsimcha]

== Quote from downs (default_357-line at yahoo.de)'s article
> dsimcha wrote:
> > == Quote from downs (default_357-line at yahoo.de)'s article
> >> I submitted a patch a while back for constant-time removeRange. Can we dredge
> > that one up and/or implement something similar? It's rather useful for things like
> > stackthreads that need to add and remove lots of ranges :)
> >> (Search the NG for "Feature req.+Patch: O(1) removeRange")
> >
> > I guess removeRange is currently O(N)?  I haven't looked.  Anyhow, I think the
> > bigger problem in practice, i.e. until N is unrealistically large, is that
> > removeRange requires taking a lock.  O(1) would be nice, though.
> >
> > What does StackThreads (I assume this is equivalent to fibers) do that it requires
> > so many add/remove ranges?
> The virtual stacks I use are being allocated via mmap. Every stack is a range.
With every context switch, the relevant ranges need to be modified - the range
that is being switched to needs to be removed (because it becomes the "main" stack
which has special GC handling), and the stack range that's being switched from
needs to be added.

IDK, that sounds a bit expensive even with O(1) removeRange.  Are you using some
home-grown impl. of StackThreads/fibers, Tango's, or D2 druntime's?  If it's
Tango's or druntime's, I haven't looked, but I would think the GC understands
stuff about them.  If it's your own, have you considered switching and maybe
submitting whatever extra features your impl. has to Tango and/or druntime?