[GRASS-user] v.distance and optimizations

[Moritz Lennert]

On 03/11/17 14:45, Eric Patton wrote:
> Hi,
> 
> I am running v.distance on a massive point vector which represents 
> coastline vertices, uploading the attributes of another point vector, in 
> this case, the vectorized point version of a DEM slope raster.
> 
> While the program is working as expected, (I have seen the output on 
> smaller files, and it looks correct), it is extremely slow because the 
> ‘from’ vector has ~ 700k points in it, and my search radius is 200 m for 
> each point. I checked htop and v.distance is only using one CPU. The 
> process has been running for about a week, and is at 69%.

It would be interesting to find out if this is due to the actual 
distance algorithm, or more to database access. You might want to try 
using the -p flag and redirect the output to a file just to see if this 
is faster.

> I was 
> wondering if there were any way to make v.distance use more than one CPU 
> (I have four)? Or perhaps there is an environment variable I’m not aware of?

AFAIK there is no parallelization in v.distance.

Moritz