Re: Boehm-Demers-Weiser conservative garbage collector and GNAT

[Ludovic Brenta <ludovic.brenta@insalien.org>]

Preben Randhol <randhol+abuse@pvv.org> writes:

> Larry Kilgallen wrote:
> > It would be a way to spend overhead to make up for a lack of cleanup
> > in the programming.
> 
> Exactly. So one would need to have GC in all implementations in order to
> have any real use for it IMHO. As one then can start with more sloppy
> coding [*].
> 
> [*] In the sense that you don't worry abut what happens to your
> allocations.

Yes.  I've never really liked GC myself, but the paper that Martin
mentions says that programmers spend up to 30% of their time doing
(and debugging) memory management, and that perhaps this 30% could be
better spent elsewhere.

This at the expense of some performance [1] and portability.  It's a
trade-off that many people may find appealing, so, I can see a point
of providing it for those who want it.  Of course, I suppose using the
GC would be optional, even if GCC or GNAT did provide it.  I tend to
think that choice is almost always a good thing.

[1] According to the paper, Boehm's GC has pretty good performance,
but GCC's compilation speed has suffered from its introduction.  Also,
in most Java virtual machines, the GC is a well-known source of
unpredictability in the performance of applications.

(the original paper also says the GC is a good debugging tool that
aids in finding memory leaks; but, of course, GNAT already has a debug
storage pool, so I don't think this is the reason Martin wants to
provide GC).

-- 
Ludovic Brenta.