[GRASS-dev] Avoiding maximum open files limit in r.series

[Sören Gebbert]

Hi,

> This is a fairly fundamental change (albeit one which shouldn't affect
> anything outside of the core lib/raster code), so it needs to be
> thoroughly tested before anything else is done in that area.

I have tested the raster functionality with r.mapcalc and r.series
excessively. No problems found so far.

>
> In addition to "native" raster maps, testing r.external/r.out.external
> GDAL-linked maps is also necessary.

While implementing spatio-temporal data import and export using
r.in.gdal, r.out.gdal and r.external i found some strange behavior:
The export of raster data works fine, but the import/linking needs a
lot more time than expected. Export with r.out.gdal 0.033s,
link/import r.external or r.in.gdal ~17s:

GRASS 7.0.svn (XYLocation at test):~/src/grass7.0/grass_trunk/temporal/tr.export
> r.info prec_1 -gs
north=80
south=0
east=120
west=0
nsres=10
ewres=10


GRASS 7.0.svn (XYLocation at test):~/src/grass7.0/grass_trunk/temporal/tr.export
> time r.out.gdal in=prec_1 out=prec_1.tif
Checking GDAL data type and nodata value...
 100%
WARNING: Unable to set projection
Exporting raster data to GTiff format...
 100%
r.out.gdal complete. File <prec_1.tif> created.

real    0m0.033s
user    0m0.012s
sys     0m0.020s


GRASS 7.0.svn (XYLocation at test):~/src/grass7.0/grass_trunk/temporal/tr.export
> time r.external in=prec_1.tif output=new_test
Projection of input dataset and current location appear to match
Reading band 1 of 1...
r.external complete. Link to raster map <new_test> created.

real    0m17.638s
user    0m17.237s
sys     0m0.016s

GRASS 7.0.svn (XYLocation at test):~/src/grass7.0/grass_trunk/temporal/tr.export
> time r.in.gdal in=prec_1.tif output=new_test_2
Projection of input dataset and current location appear to match
 100%
r.in.gdal complete. Raster map <new_test_2> created.

real    0m16.394s
user    0m16.221s
sys     0m0.044s


Best regards
Soeren