Comment author: administrator

Full_Name: Joseph E. Gonzalez
Version: 3.08.1
OS: Linux 2.6.8-1.521smp x86_64
Submission from: fleming-55.caltech.edu (131.215.87.55)

I wrote a simple program to test performance (the following one):

let rec random_list x list = match x with
| 0 -> list
| _ -> random_list (x - 1) ((Random.int 999999999)::list);;

let l = (random_list 999999 []);;

let y = (List.map (function x -> x) l);;

and compiled it using the command:
ocamlopt prof.ml -o prof

when I run it I get a segmentation fault.

This looks like you've hit a limit that your shell has on stack size. Could you
please make sure you have no limit on stack or memory size (ulimit -a, with
bash), and re-run your `prof' executable?

-- Michel Mauny

Comment author: administrator

I wrote a simple program to test performance (the following one):

let rec random_list x list = match x with
| 0 -> list
| _ -> random_list (x - 1) ((Random.int 999999999)::list);;

let l = (random_list 999999 []);;

let y = (List.map (function x -> x) l);;

and compiled it using the command:
ocamlopt prof.ml -o prof

when I run it I get a segmentation fault. This does not happen on my other
systems. When I used gdb the fault is said to be in
camlList__map_86 ()

This looks like a stack overflow (List.map is not tail-recursive).
On Intel x86, stack overflow (reported by the Unix kernel as a
segmentation fault) is caught and mapped to a Caml exception, but this
is not (yet) the case on x86_64.

You might be able to get your code to run by raising the Unix stack
size limit (command "ulimit"). Also, consider List.rev_map
(tail-recursive) instead of List.map.

Hope this helps,

• Xavier Leroy

Comment author: administrator

Just a stack overflow. Feature wish: Stack_overflow exception on AMD64/Linux.
Implemented in 3.09.