On Fri, 2005-10-14 at 10:49 +0100, Richard Jones wrote:
> I'm trying to optimise a program which is using a large amount of
> memory and consequently thrashing.
> 
> The core of the program is an iteration over a list of something like
> a million elements which consumes about 1/2 gig of RAM.  The iteration
> is:
> 
>   List.iter (
>     fun row ->
>       (* put row into database and forget about it *)
>   ) rows;
>   (* no further references to rows after this *)
> 
> This is the stdlib implementation of List.iter.  Should the garbage
> collector be able to collect the part of the list which has been
> iterated over, during the iteration?  At the moment it doesn't look
> like it's doing so.

let rows = ref [] in
(* build up the list of rows here *)

let rec doit rows = match rows with
  | [] -> ()
  | h :: t -> install_in_db h; doit t (* tail call *)
in 
  doit (let r = !rows in rows := []; r)

-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net