[GRASS-dev] problem with GridModule

[Anna Petrášová]

Hi,


On Thu, Nov 19, 2015 at 3:16 AM, Pietro <peter.zamb at gmail.com> wrote:

> Hi Anna,
>
> soory for the delay...
>
> On Mon, Nov 16, 2015 at 3:23 PM, Anna Petrášová <kratochanna at gmail.com>
> wrote:
> > On Mon, Nov 16, 2015 at 8:28 AM, Markus Neteler <neteler at osgeo.org>
> wrote:
> >> On Tue, Nov 10, 2015 at 7:58 PM, Anna Petrášová <kratochanna at gmail.com>
> >> wrote:
> >> > Maybe some bug in the pygrass raster library?
> >>
> >> Looks like a race condition?
> >
> >
> > I don't understand why would that happen, the patching done with pygrass
> > raster library is not running in parallel.
>
> Yes I have to investigate more on this to understand what it is not
> working...
>
>
> > A workaround I currently use is to patch the rasters using r.patch,
> which is
> > in the case of viewsheds OK (the overlaps are the same), however in other
> > cases such as interpolation, the overlaps are different and r.patch won't
> > patch the rasters as desired, that's why the GridModule is using pygrass
> > raster library I assume.
>
> I've modified r.tile to split and merge using an optional parameter
> for the overlap (perhaps I should create just a new module r.untile
> instead of adding a new flag in r.tile...).
> The approach it is much faster than the actual implementation of
> r.patch because minimize reading disk operations since we are not
> merging general raster maps with undefined bboxes but  well known
> tiles...
> Unfortunately the implementation still experimental and has some
> problems. I will not able to work on this before next year... maybe I
> can put the modified version of r.tile in the sandbox repo.


That would be great addition, I think I would keep it in r.tile, r.untile
sounds a little weird. I don't think I would have time to look at it
either, but please put it in sandbox, so that it's somewhere.

I am also having problem that sometimes I am getting
RuntimeError "Execution of subprocesses was not successful"

it appears randomly, once or twice in 100 runs, but it causes quite a bit
of trouble. On Windows I was getting this in half of the cases (but with
different data and use case so it's difficult to compare). I think the
GridModule is great and makes parallelization so much easier, so I would
love to see it working more reliably. It's clear to me that you don't have
time to look at it now, neither do I, so I am mainly reporting these
issues...

Thank you!

>
> Let me know.
>
> Pietro
>
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