[GRASS5] Re: [bug #3877] (grass) r.to.vect: severe memory leaks, I'm helpless

[Roger Bivand]

On Mon, 5 Dec 2005, Maciek Sieczka wrote:

> On pon, 2005-12-05 at 13:38 +0100, Radim Blazek via RT wrote:
> > please read old mails on this problem. I dont have time to explain it
> > again and again. AFAIK there are no big memory leaks.
> 
> Is it aknowledged by Grass developers that a machine freeze at 5 mln
> vector points file is a BUG (no matter what the reason is)?
> 
> If it is aknowledged, can we expect it to be fixed? When - soon, month
> time, year time? Or is it going to be a "feature" and left as is?

I think this is unfair. There has been progress in GRASS 6 on this, and 
the vector architecture is much stronger than it was in GRASS 5 for 
moderate and large data sets, but not for XXL. 

Have you considered using GRASS 5, which has sites, a very much simpler 
data model for points? Have you considered tiling your data - reading 
portions of your data and patching the resulting spline surfaces? Once you 
have the surface, you can transfer it to GRASS 6, because as yet the 
raster storage data model is effectively unchanged. 

This is not a bug, it is a mis-match of data models and intentions. While 
accepting that freezing (meaning causing total OS failure, or rather 
occupation of all machine resources? - I don't think that a non-root user 
on a sensible OS can freeze the system so that a hard shutdown (pull 
power) is required) is unfortunate, it is usually caused by 100% CPU use 
and swapping caused by memory being fully occupied. In well-written 
software, like GRASS 6 vector or R, say, there is a balance between how 
things are written, perceived needs, and user perceptions. The GRASS 6 
vector data model handles areas and lines pretty well, but because it is 
trying harder on these, is not well suited to XXL points data sets. My 
understanding is that the authors of the *.rst programs themselves also 
use GRASS 5, among other things because its sites data model is very 
simple.

Best wishes,

Roger

> 
> Maciek
> 
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no