[GRASS-user] r.sun.daily with multiple CPU cores: error uncompressing raster data ...

[Dylan Beaudette]

Hi everyone,

First of all, thanks in advance for the r.sun.daily module which is a
nice replacement for my amateurish attempts over the last 12 years.

I am currently working on an annual beam radiance map for a large
geographic region, at 30m res: 70,953 x 46,964 cells. This is far too
large for a single pass of r.horizon or r.sun on my machine so I have
split the data into 5,000 x 5,000 cell tiles with 100 cells of
overlap. This seems to be sufficient for my purposes and the edge
effects are tolerable.

At 8-15 minutes / tile / day (r.sun) and 54 tiles this job calls for
multiple CPU cores. All of the parallel processing that I use is (as
far as I know) contained within the same region.


I have had good success with running r.horizon in parallel via GNU
parallel like this:

# 1: start angle
# 2: angle step
# 3: elevation tile
seq 0 $step 330 | parallel --gnu --progress "bash make-hz-maps.sh {}
$step $elev"

Which is just a wrapper around r.horizon and run in parallel "within" tiles.

Next, I run r.sun.daily (8 CPU cores) within tiles:

r.sun.daily --overwrite elevation=$elev aspect=$asp slope=$slope \
start_day=1 end_day=365 beam_rad=$beam horizon_basename=hzangle
horizon_step=$step nprocs=8


The r.sun.daily modules finishes without error about 50-60% of the
time, results look good. The other 50-40% of the the time I get this:


ERROR: Error uncompressing raster data for row 2605 of
       <r_sun_crop8255_beam_rad_tmp_352>
*** buffer overflow detected ***: g.message terminated
======= Backtrace: =========
/lib/x86_64-linux-gnu/libc.so.6(+0x7329f)[0x7f8b9a70129f]
/lib/x86_64-linux-gnu/libc.so.6(__fortify_fail+0x5c)[0x7f8b9a79c83c]
/lib/x86_64-linux-gnu/libc.so.6(+0x10d710)[0x7f8b9a79b710]
/lib/x86_64-linux-gnu/libc.so.6(+0x10cc19)[0x7f8b9a79ac19]
/lib/x86_64-linux-gnu/libc.so.6(_IO_default_xsputn+0xbc)[0x7f8b9a70961c]
/lib/x86_64-linux-gnu/libc.so.6(_IO_vfprintf+0x1cc5)[0x7f8b9a6d9905]
/lib/x86_64-linux-gnu/libc.so.6(__vsprintf_chk+0x84)[0x7f8b9a79aca4]
/usr/local/grass-7.5.svn/lib/libgrass_gis.7.5.svn.so(+0x1343c)[0x7f8b9aa6a43c]
/usr/local/grass-7.5.svn/lib/libgrass_gis.7.5.svn.so(G_fatal_error+0xbf)[0x7f8b9aa6accf]
g.message(main+0x254)[0x400dd4]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf5)[0x7f8b9a6aff45]
g.message[0x400ea2]


I can't seem to replicate the problem, as subsequent runs with the
same parameters and in the same tile are successful! This leads me to
think that:

* some aspect of this approach is not thread safe
* there is something wrong with my computer
* there is a subtle bug in the raster writing / reading code when
invoked in parallel


I have encountered similar raster reading errors in the past,
typically in the context of parallel processing:

https://trac.osgeo.org/grass/ticket/2762

https://trac.osgeo.org/grass/ticket/2764

http://osgeo-org.1560.x6.nabble.com/Error-reading-raster-data-for-row-xxx-only-when-using-r-series-and-t-rast-series-td5229569i20.html

https://lists.osgeo.org/pipermail/grass-dev/2015-July/075691.html


Here is some information on my system and version of GRASS:

 ./configure  --enable-64bit --with-libs=/usr/lib --without-pthread
--without-odbc --without-mysql --with-readline --with-cxx
--enable-largefile --with-freetype
--with-freetype-includes=/usr/include/freetype2 --with-sqlite
--with-python --with-geos=/usr/local/bin/geos-config --without-opencl
--with-opencl-includes=/usr/include/CL/ --with-postgres
--with-postgres-includes=/usr/include/postgresql/
--with-postgres-libs=/usr/lib/
--with-proj-share=/usr/local/share/proj/

version=7.5.svn
date=2017
revision=r71964
build_date=2017-12-21
build_platform=x86_64-pc-linux-gnu
build_off_t_size=8


Any ideas?

I haven't had a chance to inspect the maps in question as r.sun.daily
deletes the intermediate pieces on error.

Thanks!
Dylan