On Wednesday, 24 September 2014 at 08:13:15 UTC, Marc Schütz
wrote:
On Tuesday, 23 September 2014 at 18:39:09 UTC, Oscar Martin
wrote:
On Tuesday, 23 September 2014 at 01:58:50 UTC, Rikki
Cattermole wrote:
Short, I dislike pretty much all changes to __gshared/shared.
Breaks too many things.
Atleast with Cmsed, (I'm evil here) where I use __gshared
essentially as a read only variable but modifiable when
starting up (to modify need synchronized, to read doesn't).
Yeah, these changes break many things, and so are not suitable
for D2. My intention was only to point out how expensive is
for the GC to deal with shared memory.
Come to think a little more: what if each thread can have its
own GC, but by default all use the current GC (this would
require minimal changes to druntime). "__gshared", "shared"
and "immutable", continue as now, which does not break
anything. If I as a programmer take care of managing (either
manually or through reference counting) all of the shared
memory ("__gshared", "shared" or "immutable") that can be
referenced from multiple threads, I could replace in my
program the global GC by a indiviual thread GC
I'll try to implement a GC optimized for a thread and try that
solution
There can also be a shared _and_ a local GC at the same time,
and a thread could opt from the shared GC (or choose not to opt
in by not allocating from the shared heap).
Yes, a shared GC should be a possibility, but how you avoid the
"stop-the-world" phase for that GC?
Obviously this pause can be minimized by performing the most work
out of that phase, but after seeing the test of other people on
internet about advanced GCs (java, .net) I do not think it's
enough for some programs
But hey, I guess it's enough to cover the greatest number of
cases. My goal is to start implementing the thread GC. Then I
will do testing of performance and pauses (my program requires
managing audio every 10 ms) and then I might dare to implement
the shared GC, which is obviously more complex if desired to
minimize the pauses. We'll see what the outcome
