[GRASS-user] Issue with r.sun.daily in combination with multiprocessing

GRASS GRASS user
1

Hi list,

I am trying to build a script to run r.sun.daily so it only runs for the center day of each month of a year. However, when the code starts r.sun.daily script, it creates 4 processes for the first day but only 2 processes for any following day. Even though I set ’ nprocs=4’ when calling the script.

I am trying to use a similar setup as the r.horizon parallel script found here. This script uses the multiprocessing module to have the script wait until the process is finished before feeding new parameters to a worker. I edited this so it changes the ‘start_day’ and ‘end_day’ parameters, but only creates one worker that launches the r.sun.daily script with ‘nprocs=4’, then waits until this run is done using ‘.join’, before providing the worker with a different start and end day and starting r.sun.daily again with ’ nprocs=4’.

What could be the issue that it switches to two processes after the 1st day?

Regards,

Tinsley

(attachments)

grassRsun.py (8.3 KB)

2

On Mon, May 15, 2017 at 7:17 AM, Tinsley Wolfs <twolfs15@student.aau.dk> wrote:

Hi list,

I am trying to build a script to run r.sun.daily so it only runs for the
center day of each month of a year. However, when the code starts
r.sun.daily script, it creates 4 processes for the first day but only 2
processes for any following day. Even though I set ' nprocs=4' when calling
the script.

I am trying to use a similar setup as the r.horizon parallel script found
here. This script uses the multiprocessing module to have the script wait
until the process is finished before feeding new parameters to a worker. I
edited this so it changes the 'start_day' and 'end_day' parameters, but only
creates one worker that launches the r.sun.daily script with 'nprocs=4',
then waits until this run is done using '.join', before providing the worker
with a different start and end day and starting r.sun.daily again with '
nprocs=4'.

What could be the issue that it switches to two processes after the 1st day?

You have:

dayEnd = dayStart + 1

so it will use only 2 cores, one for dayStart and one for dayEnd.
Maybe you want to use day_step parameter instead of specifying the
individual days?

Anna

Regards,
Tinsley

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