let x = ... in object ...

let x = ... in object ...

[Guillaume Hennequin]

[-- Attachment #1: Type: text/plain, Size: 566 bytes --]

Dear list,

I was just wondering whether in

class a =
  let x = Array.make 10000 0. in
object
  val y = Array.copy x
  ...
end

x will be garbage collected or not.
(this is just an example, I know creating x and copying is just doesn't make
sense, but I wanted to point out that in my case, x doesn't need to be kept,
but just used during object creation. I would like it to be garbage
collected).
I roughly recall a previous post where I think the reply was "intermediate
values such as x are "kept" as members of the class", but I'm not sure.

Thanks

Guillaume.

[-- Attachment #2: Type: text/html, Size: 658 bytes --]

Re: [Caml-list] let x = ... in object ...

[Martin Jambon]

Guillaume Hennequin wrote:
> Dear list,
> 
> I was just wondering whether in
> 
> class a =
>   let x = Array.make 10000 0. in
> object
>   val y = Array.copy x
>   ...
> end

# class a = let () = print_endline "hello" in object end;;
hello
class a : object  end


Maybe you mean the following:

class a () =
  let x = Array.make 10000 0. in
object
  val y = Array.copy x
  ...
end


> x will be garbage collected or not.
> (this is just an example, I know creating x and copying is just doesn't
> make sense, but I wanted to point out that in my case, x doesn't need to
> be kept, but just used during object creation. I would like it to be
> garbage collected).
> I roughly recall a previous post where I think the reply was
> "intermediate values such as x are "kept" as members of the class", but
> I'm not sure.
> 
> Thanks
> 
> Guillaume.
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Caml-list mailing list. Subscription management:
> http://yquem.inria.fr/cgi-bin/mailman/listinfo/caml-list
> Archives: http://caml.inria.fr
> Beginner's list: http://groups.yahoo.com/group/ocaml_beginners
> Bug reports: http://caml.inria.fr/bin/caml-bugs


-- 
http://mjambon.com/

Re: [Caml-list] let x = ... in object ...

[Guillaume Hennequin]

[-- Attachment #1: Type: text/plain, Size: 812 bytes --]

> # class a = let () = print_endline "hello" in object end;;
> hello
> class a : object  end
>
>
> Maybe you mean the following:
>
>
?
well, I have just tested this in the toplevel

class a n =
  let x = Array.make_matrix n n 0. in
object(self)
  val y = Array.init n (fun i -> Array.copy x.(i))
  method y = y
end ;;

let mya = new a 10000 ;;

---------> memory consumption 78.5 (from top)

Gc.full_major () ;;

---------> memory consumption is still 78.9

let mya = () ;;
Gc.full_major () ;;

---------> memory consumption is now 0.1

Furthermore, in a fresh ocaml toplevel,
let x = Array.make_matrix 10000 10000 0. ;;
---------> memory consumption = 39.5
(half of the previous memory usage)

So, it seems that x, although not useful after the object creation, is not
garbage collected.

??

Cheers
Guillaume.

[-- Attachment #2: Type: text/html, Size: 1213 bytes --]

Re: [Caml-list] let x = ... in object ...

[Martin Jambon]

Guillaume Hennequin wrote:
> 
> 
> 
>     # class a = let () = print_endline "hello" in object end;;
>     hello
>     class a : object  end
> 
> 
>     Maybe you mean the following:
> 
> 
> ?

I was just pointing out that "class a = let x = ... in object ... end"
creates x once and for all when the class is defined, and x will therefore not
be GC'ed because of the language definition, not because of its implementation.


Martin
-- 
http://mjambon.com/

Re: [Caml-list] let x = ... in object ...

[Jacques Garrigue]

From: Guillaume Hennequin <guillaume.hennequin@epfl.ch>

> well, I have just tested this in the toplevel
> 
> class a n =
>   let x = Array.make_matrix n n 0. in
> object(self)
>   val y = Array.init n (fun i -> Array.copy x.(i))
>   method y = y
> end ;;
> 
> let mya = new a 10000 ;;
> 
> ---------> memory consumption 78.5 (from top)
> 
> Gc.full_major () ;;
> 
> ---------> memory consumption is still 78.9

Try with

class a n =
  let x = Array.make_matrix n n 0. in
object(self)
  val y = Array.init n (fun i -> Array.fold_left (+) 0. x.(i))
  method y = y
end ;;

After the gc, x is collected.
What you are seeing is the size taken by y.

Jacques Garrigue