[Haskell-cafe] GC [Is Haskell a Good Choice for Web Applications?]

[Daniel Fischer]

Am Donnerstag 07 Mai 2009 22:01:11 schrieb Andrew Coppin:
> Simon Marlow wrote:
> > http://hackage.haskell.org/trac/ghc/ticket/698
>
> I presume that the reason for this is to avoid handing memory back only
> to immediately need it again? (I.e., we don't want to be constantly
> asking the OS to allocate and deallocate memory. Allocate it once and
> then let the RTS handle it.)
>
> How hard would it be to add a function to ask the RTS to shrink the
> allocated memory? E.g., you do something that you know consumes lots of
> RAM, you finish doing it, you know that your live set has probably gone
> way down now, so you ask the RTS to release some RAM if possible. Would
> that be difficult?

Another idea, I have no idea how hard or sensible it is:
What if the GC detects how much memory is currently used (it does already do that, doesn't 
it?) and how much is allocated from the OS, and if less than a third or a quarter of the 
allocated memory is used, return the memory that exceeds twice the used memory to the OS?
Behaviour might be configurable by an RTS flag.