Re: GNAT's stack checking in Ubuntu 9.04 (and Shootout regex-dna)

[Georg Bauhaus <rm.tsoh.plus-bug.bauhaus@maps.futureapps.de>]

Ludovic Brenta wrote:
> Georg Bauhaus wrote on comp.lang.ada:
>> Georg Bauhaus wrote:
>>> The GNAT that comes with Ubuntu 9.04 (GCC 4.3.3)
>>> produces storage errors where GNAT on Debian Lenny
>>> (GCC 4.3.2) and GNAT 2007 on Windows (4.3.1) don't.
>> The latter is 4.1.3, sorry.
> 
> From the symptoms you describe and the workaround you found, it seems
> to me not related to the compiler but rather to the way the kernel is
> configured. It looks like Ubuntu's default stack size is much smaller
> than on Debian or Windows. What does "ulimit -s" say on your Ubuntu
> and Debian?

8192 is the default output of ulimit -s on Ubuntu.

I had set ulimit -s $((8192 * 64)) on both Ubuntu 9.04
and Debian 5 and both exhibit the same symptoms.  Why?

More guesswork: Is an empty Unbounded_String a heavy
construct?  Observing the memory consumption of
regexdna, for reading and matching the ~50 Mo input
it does not consume more than about ~60 Mo, according
to free(1) and top.  Then, the stack allocation of the lines
array seems to hit some memory boundary. (625_000 default
initialized Vstrings, which is a subtype of Unbounded_String.)
valgrind (in default mode) did not find anything IIRC.