On Thursday, 3 January 2013 at 11:40:37 UTC, deadalnix wrote:
On Thursday, 3 January 2013 at 11:26:11 UTC, Thiez wrote:
On Thursday, 3 January 2013 at 10:17:19 UTC, deadalnix wrote:
Generational seems completely unrealistic.
Why?
Tracking reference from old gen to new gen require read/write
barriers.
Plus, it is unclear what the win is, generational GC is way
less interesting when the GC cannot move.
Last time I talked with Walter (on reddit) regarding this he
mentioned papers on "mostly copying GCs" where one can have a
generational imprecise GC which moves most of the data but not
all of it. For example, without stack maps we don't know where in
the stack are pointers, so we don't move objects possibly
referenced from stack. However those referenced only from the
heap can be moved since we have precise heap info. I recall this
is the current situation of Rainer's mostly precise GC used in
VisualD - it has precise maps of the heap but not of the stack.
+1 to better GC as a project. An easier but still possibly
interesting goal would be changing current (or better Rainer's)
GC to use parallel marking and lazy sweeping, same things that
were done for Ruby interpreter recently. That should make GC
pauses much shorter and it doesn't require rewriting most of the
GC.
