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

[Vadim Godunko <vgodunko@gmail.com>]

On Aug 4, 1:17 pm, Georg Bauhaus <rm.tsoh.plus-
bug.bauh...@maps.futureapps.de> wrote:
>
> 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?
>
This size is too small, you can setup unlimited size by

ulimit -s unlimited

> 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.

Unbounded_String uses constant size of stack for object itself and
uses dynamic size on heap for actual value. But note, concatenation
operations of strings and arrays can use stack for intermediate
result, thus can be the source of problem.