Re: GNAT GPL for Mac OSX stack checking problem

On Fri, 7 Oct 2005 13:00:10 UTC, Jeff Creem <jcreem@xxxxxxxxx> wrote:

> Kevin K wrote:
> > The compiler and GPS seem to work, it is the generated test driver
> > that I'm having problems with.
> >
> > I saw 10.3 referenced when I downloaded it, but I have a history with
> > the Linux versions where you can, at times, run the compiler on a
> > different version than they built on. For instance, the versions
> > build for Redhat 7.1 could run on 7.2, 7.3, 8, EL 2.1, but GLIBC
> > differences essentially required a new version from Adacore for RH9,
> > EL3, etc. (The change to the new threading library).
> >
> > I just took a look at the ulimit command. I would have to look at the
> > documentation to increase it under macos, but traditionally, the stack
> > you are changing with this command is the Environment stack, which is
> > the stack for the actual main procedure, NOT the tasks for individual
> > tasks. If GNAT, on the Mac, is putting all the tasks I declared in
> > the procedure declare section into the environment stack, that is
> > different behavior than any other Ada compiler I've used, since the
> > Linux GNAT uses the heap, Rational Apex uses the heap, the VADs Ada83
> > compiler used the heap, and Alsys on Unix used the heap.
> >
> > Essentially, my test procedure was
> >
> > procedure test_tasks is
> >
> > task type task_type is
> > pragma storage_size(10000000);
> >
> > entry start;
> > end;
> >
> > task body test_tasks is
> >
> > begin
> >
> > accept start;
> >
> > loop
> > putline("task num");
> > delay 10.0;
> > stack_user;
> > end loop;
> > end;
> >
> > procedure stack_user is
> > buffer:string(1..2048);
> >
> > begin
> > buffer(1):=' ';
> > stack_user;
> > exception
> > when storage_error=> text_io.put_line("Storage_Error");
> > end;
> >
> > the_tasks : array(1..10) of task_type;
> >
> > begin
> >
> > --Call Start on all tasks
> >
> > end;
> >
> >
>
> It is not clear that one should expect to see 100 Megs actually used on
> all OS's if the stack check logic is flawed. Some OSs do not actually
> commit usage of the memory until it is accessed. Given the way this is
> written, it seems like it would be perfectly valid for the first task to
> take off and run into that infinite recusion and blow its stack before
> any other task gets any CPU time. Now if they each did this before the
> program terminated I guess one would see the 100 Meg usage.. So it
> sounds like the problem is not really that you are running into an early
> stack limit but rather that the stack checking is not operating properly
> resulting in the program terminating instead of each tasking running one
> after another.
>
> Sounds to me like the interaction of gcc and macos is not doing proper
> stack checking.


I'll stick in a small delay statement in the recursive procedure that
will slow down the tasks, in case, for some reason, the Macos version
of the runtime doesn't timeslice.

Regardless, I would have thought that the memory usage according to
top would have shown at least 10 meg if only 1 task was running.
.

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