> 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.

Because rows is still accessible after the List.iter  so it is normal that it is not garbage collected.

I had the same kind of problem and to optimize it I choose to produce the elements of rows lazily
(but then I had another problem with the Lazy modudle where elements were not garbage collected so 
I use my own lazy module (simple via closure) and it works perfectly well).




> 
> Rich.
> 
> -- 
> Richard Jones, CTO Merjis Ltd.
> Merjis - web marketing and technology - http://merjis.com
> Team Notepad - intranets and extranets for business - http://team-notepad.com
> 
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