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From: Damien Doligez <damien.doligez@inria.fr>
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To: caml users <caml-list@inria.fr>
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Subject: Re: [Caml-list] memory leak in toplevel? or, how to implement sizeof


On 2011-01-06, at 15:59, Jim Pryor wrote:

> Actually I think the overhead should be 22. Making it 22 gives these
> sensible results:

The overhead is exactly the heap space used by the value returned by
Gc.stat.  In your case it is 23 words, not 22.

>    # sizeof (fun x -> x) 10;;
>    - : int * int = (1, 10)
> 
> That is, one word for the int.

The int is not allocated in the heap, so the result should be 0.

It is best to let ocaml compute the overhead, because it will be different
on 32- and 64-bit machines:

  let overhead =
    let first = Gc.((stat()).minor_words) in
    let second = Gc.((stat()).minor_words) in
    int_of_float (second -. first)
  ;;

-- Damien