[GRASS-dev] [GRASS GIS] #2074: r3.mapcalc neighborhood modifier hash table and tile errors

[GRASS GIS]

#2074: r3.mapcalc neighborhood modifier hash table and tile errors
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 Reporter:  wenzeslaus   |       Owner:  grass-dev@…              
     Type:  defect       |      Status:  new                      
 Priority:  normal       |   Milestone:  7.0.0                    
Component:  Raster3D     |     Version:  svn-trunk                
 Keywords:  r3.mapcalc   |    Platform:  All                      
      Cpu:  Unspecified  |  
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Comment(by huhabla):

 I will try an answer, Glynn, please correct me if i am wrong.

 As far as i understand set's {{{putenv("WORKERS=1")}}} the number of
 worker threads that have parallel read access to raster 3d maps (reading
 values) and perform mapcalc sub-expression evaluation. Since the raster 3d
 library was not designed to allow parallel access, a race condition
 happens when several threads try to read values in parallel. In this case
 the raster 3d map specific tile index gets corrupted.

 The environment variable WORKERS will be analysed in lib/gis/worker.c that
 implements the creation and execution of pthread based worker threads. The
 default number of workers is 8, but can be overwritten using the
 environment variable WORKERS.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2074#comment:6>
GRASS GIS <http://grass.osgeo.org>