On Tuesday, 24 February 2015 at 09:30:33 UTC, Tobias Pankrath
wrote:
I suspect it would be a terrible performance hit.
It would be nice to have some numbers backing this up.
This the approach taken by Active Oberon and Modula-3.
Pointers are GC by default, but can be declared as untraced
pointers in code considered @system like in D.
Do they have concurrent gc and emit barriers for each write to a
default pointer? Do they have precise scanning and don't scan
the
untraced pointers? Are the meaningful performance comparisons
between the two pointer types that would enable us to estimate
how costly emitting those barriers in D would be?
Both Active Oberon and Modula-3 support threading at language
level, so multi-threading is a presence on their runtimes.
The latest documentation available for Active Oberon is from 2002.
http://e-collection.library.ethz.ch/view/eth:26082
Originally it was a concurrent mark-and-sweep GC, with stop the
world phase for collection.
Other algorithms are discussed on the paper. Sadly ETHZ is done
with Oberon as their startup failed to pick up steam in the
industry (selling Component Pascal, an evolution of Oberon-2).
As for Modula-3, due to the way the the whole DEC, Olivetti,
Compaq, HP process went, it isn't easy to find much documentation
online. I had a few books.
The latest implementation had a concurrent incremental
generational GC.
https://modula3.elegosoft.com/cm3/doc/help/cm3/gc.html
2002 is also around the same time that Modula-3 developed was
stopped.
Dylan, which I just remembered while writing this, used the MPS
collector.
http://www.ravenbrook.com/project/mps/doc/2002-01-30/ismm2002-paper/ismm2002.html
Sadly the industry went JVM/CLR instead, and only now we are
getting back to native systems programming with GC languages.
If those languages had been picked up by the industry instead of
JVM/CLR, the situation could be quite different.
As always, it is a matter where the money for research gets
pumped into.
--
Paulo
