[GRASS-dev] [GRASS GIS] #2750: LZ4 when writing raster rows; better than double I/O bound r.mapcalc speed

[GRASS GIS]

#2750: LZ4 when writing raster rows; better than double I/O bound r.mapcalc speed
--------------------------+---------------------------
  Reporter:  sprice       |      Owner:  grass-dev@…
      Type:  enhancement  |     Status:  new
  Priority:  normal       |  Milestone:  7.1.0
 Component:  Raster       |    Version:  svn-trunk
Resolution:               |   Keywords:  ZLIB LZ4 ZSTD
       CPU:  OSX/Intel    |   Platform:  MacOSX
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Comment (by wenzeslaus):

 Replying to [comment:6 wenzeslaus]:
 > Replying to [comment:5 sprice]:
 > > I just uploaded a new version of the code that shouldn't fail any
 additional unit tests, and I've added unit tests to r.compress that test
 reading/writing the different compression schemes.
 >
 > Nice. Runs for me as well.

 Bad news. Only the r.compress tests runs well for me. I messed up the
 environmental variables.

 Now (with `export GRASS_INT_LZ4=1`) I'm getting fails from various tests.

 Wrong values in the result (for example):

 {{{
 ./raster/r.series.interp/testsuite/interp_test.py
 ======================================================================
 FAIL: test_infile (__main__.InterpolationTest)
 ----------------------------------------------------------------------
 AssertionError: The actual maximum (269) is greater than the reference
 one (200) for raster map prec_2 (with minimum 200)
 }}}

 Possible segmentation faults:

 {{{
 ./raster/r.gwflow/testsuite/validation_7x7_grid.py
 =====================================================================
 FAIL: test_transient (__main__.Validation7x7Grid)
 ---------------------------------------------------------------------
 AssertionError: Running <r.gwflow> module ended with non-zero return code
 (-11)
 }}}

 {{{
 ./temporal/t.rast.univar/testsuite/test.t.rast.univar.sh
 ...
 grass.exceptions.CalledModuleError: Module run ['r.univar', '-ge',
 u'map=prec_1 at __temporal_t_rast_univar_test.t. rast.univar'] ended with
 error
 Process ended with non-zero return code -11.
 }}}

 With the changes applied but with default settings (`unset
 GRASS_INT_LZ4`), I'm getting the same results as at the
 [http://fatra.cnr.ncsu.edu/grassgistests/reports_for_date-2015-10-08-07-00/report_for_nc_basic_spm_grass7_nc/testfiles.html
 test server]. r.compress test runs well in both cases.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2750#comment:7>
GRASS GIS <https://grass.osgeo.org>