[GRASS-user] Parallel processes

[Dylan Beaudette]

Hi,

Are there any reasons to prefer sequential operations (that do not
alter the region) vs. parallel operations?

For example:

# this
seq 1 30 | parallel -j8 --gnu --progress r.surf.gauss --o --q
output=testing_00{}

# vs.

# this
for map in `seq 1 30`
do
r.surf.gauss --o --q output=testing_00$map
done


I have consulted the relevant page on the wiki:

https://grasswiki.osgeo.org/wiki/Parallel_GRASS_jobs

... and it does appear to discourage the first example above. Anyone
else have some examples of this kind of workflow and potential
caveats?

I have noticed that there can be a significant speed bump when running
some tasks in parallel, especially when the source files are stored on
a SSD.

Thanks,
Dylan