Re: [Caml-list] memory usage

[Richard Jones <rich@annexia.org>]

On Fri, Jul 11, 2008 at 03:49:26PM -0400, Jean Krivine wrote:
> I am trying to run a stochastic simulator (written in ocaml) on a huge
> data set and I have the following error message:

I can confirm that OCaml works fine with huge datasets, on 64 bit
platforms anyway.

> sim(9595) malloc: *** mmap(size=1048576) failed (error code=12)
> *** error: can't allocate region
> *** set a breakpoint in malloc_error_break to debug
> Fatal error: out of memory.
> 
> My system:
> 
> Mac Pro running OS X 10.5.4
> Processor:  2 x 2.8 GHz Quad-Core Intel Xeon
> Memory:  10 GB 800 MHz DDR2 FB-DIMM
> 
> Does someone know what happened? Do you have any idea of any parameter
> I could tune in order to avoid that?

Is the compiler 32 bits or 64 bits on this machine?  Try doing:

  $ ocaml
  # Sys.word_size ;;

It should print out either '32' or '64'.

Also run your program under whatever the OS X equivalent of 'strace'
is (ktrace?) to find out exactly why the mmap call fails.

OCaml <= 3.10.2 on Linux suffers a nasty problem with its use of mmap
and randomized address spaces
(https://bugzilla.redhat.com/show_bug.cgi?id=445545#c9) but it doesn't
seem like this is the same issue.

Rich.

-- 
Richard Jones
Red Hat