[Nix-dev] Why Nix-0.16 so hungry on ressources (mem + cpu) ?

[Lluís Batlle i Rossell]

On Mon, Oct 31, 2011 at 07:50:24PM +0100, Eelco Dolstra wrote:
> On 10/31/2011 06:51 PM, Lluís Batlle i Rossell wrote:
> 
> >> So NixOS system evaluation can run in 63 MiB.
> > 
> > It depends on having X or not, etc. 
> 
> This is a fairly big config with X and KDE.

Ok
> 
> > And a bad guess on the initial heap size may
> > be bad too.
> 
> How so?

A too high initial heap size given to the gc can make the process take more
memory than the user may expect. Why did you specify the size in your tests?

> > And how much of that memory can be freed before building? 
> 
> All of it in the case of nix-build, since the process that does the evaluation
> (nix-instantiate) finished before the actual build is done (nix-store -r).  This
> is not the case for nix-env however.  It probably could be a bit more aggressive
> in freeing up GC roots.

Ok, that's why I remember troubles related to it not being freed. I think it
would be quite an improvement to make nix-env free that memory before building.

Thank you!