Re: Languages don't matter. A mathematical refutation

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Sat, 04 Apr 2015 13:44:49 -0700, Paul Rubin wrote:

> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> writes:
>> In Ada memory management is automatic
> 
> Do you mean something other than stack allocation and "new"?

Stack

>> Indeterministic time is of minor importance compared to
>> indeterministic behavior in general, which means the program being
>> non-testable and unmaintainable.  
> 
> Dennis said specifically, his program needs determinstic time.  Some
> programs are like that.

He could run GC task at the lowest priority level. There would be hell of
priority inversion problems upon finalization, but GC does not work well
with finalization anyway. The latter is again the issue of
non-deterministic behavior in general, which is far more serious than
real-time arguments [*].

>> having it non-testable eliminates all means of quality assurance. End
>> of story.
> 
> I don't think that's right.  Being unable to statically analyze GC means
> you can't prove your program will never crash from memory exhaustion.
> In avionics, that may be intolerable and you better not use GC.  In
> other areas (example: compilers), you may care more that your program
> never computes a wrong result than that it never crash, so if after
> reasonable testing it doesn't seem to have memory leaks, you are fine
> and GC is great.

It is an especially interesting example because exactly GNAT or GCC, don't
know which of them, has a huge problem with memory consumption. I don't say
it is because of GC [**], but it is the problem you said irrelevant, which
makes it sometimes impossible to compile Ada program at a 32-bit system.

---------------
* Real-time arguments are kind of Godwin Law in programming.

**  Most compilers use arena pools for data structures. It would be insane
to deploy GC there, IMO.
 
-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de