Re: Language Challenge 2000 - Update

[dvdeug@x8b4e53cd.dhcp.okstate.edu (David Starner)]

On Fri, 4 Feb 2000 07:53:54 -0800, Brian Rogoff <bpr@shell5.ba.best.com> wrote:
>On 3 Feb 2000, David Starner wrote:
>> On Thu, 3 Feb 2000 12:01:44 -0800, Brian Rogoff <bpr@shell5.ba.best.com> wrote:
>> >On 3 Feb 2000, David Starner wrote:
>> >> >For GC, I suppose you'd have to use AppletMagic. 
>> >> Or wrap the Boehm-Weiser GC library.
>> >
>> >Yuk! How about a real GC for Ada someone? :-)
>> 
>> What's wrong with the Boehm-Weiser library? 
>
>What is the opposite/dual of a "conservative" garbage collector?
One that collects stuff that's in use? (-: 

>Answer that question and you can guess what I don't like with this
>approach. I'll admit that its probably fine for lots of tasks though.

You aren't going to use a garbage collector with tight memory constraints
anyway. Many large programs have unbounded memory leaks, whereas the BW
garbage collector's uncolleted unused memory will stay bounded over the
run of the program. With systems that run on PC's, reasonably bounded memory 
leaks aren't a problem.

>> It's known to work with GCC/GNAT (the Java frontend depends on it), it
>> interfaces nicely with other languages, and it works in most modern
>> OS's. 
>
>Whatever makes you happy. To use a line Ada programmers like to throw at 
>C folk: "I wouldn't fly in a plane whose software used a conservative 
>GC!"

Why? What is about conservative GC that makes it a danger? Also,
the main point of conservative GC is in an open system (a Unix program
for instance) a real GC makes interfacing with other langugages difficult.
In a closed system (a plane), I would think you'd use a "real" GC just
because there's no reason not to. (Besides extra memory usage, unpredicatable
pauses due to GC, etc.)

Now, OTOH, if you were talking about BW GC and GNAT, I'd agree. 
In theory, GCC can do optimizations that confuse garbage collection.
In practice, Jeffrey Law (one of the big GCC guys) thinks it's a problem,
whereas others disagree (including, apparently, the Java GCC people.)

-- 
David Starner - dstarner98@aasaa.ofe.org
Only a nerd would worry about wrong parentheses with
square brackets. But that's what mathematicians are.
   -- Dr. Burchard, math professor at OSU