[GRASS-dev] [GRASS GIS] #2033: Moving g.pnmcomp to lib/display to improve render performance of wxGUI

[GRASS GIS]

#2033: Moving g.pnmcomp to lib/display to improve render performance of wxGUI
----------------------------------------------+-----------------------------
 Reporter:  huhabla                           |       Owner:  grass-dev@…              
     Type:  enhancement                       |      Status:  new                      
 Priority:  major                             |   Milestone:  7.0.0                    
Component:  wxGUI                             |     Version:  svn-trunk                
 Keywords:  display, Python, multiprocessing  |    Platform:  All                      
      Cpu:  All                               |  
----------------------------------------------+-----------------------------

Comment(by huhabla):

 I am not fully convinced using the mmap() approach for IPC. It is not
 guaranteed that mmap() is faster then the usual file I/O.[1]

 I have written a small python script to test the performance of d.rast and
 d.vect using the north carolina sample dataset. The script is attached. I
 am using the PNG and Cairo driver, switching mmap on and of for different
 window sizes. In addition i call the d.rast (1x) and d.vect (2x) modules
 in parallel to measure a render speed gain. The composition is still
 missing, but i will add the PIL approach available in the grass wiki with
 python.mmap support. Here is the script:

 {{{
 # -*- coding: utf-8 -*-
 from grass.pygrass import modules
 import os
 import time

 parallel = [True, False]
 drivers = ["png", "cairo"]
 mmap_modes = ["FALSE", "TRUE"]
 sizes = [1024, 4096]

 def render_image(module, driver="png", pngfile="test.png",
                  size=4096, mapped="TRUE"):
     os.putenv("GRASS_RENDER_IMMEDIATE", "%s"%driver)
     os.putenv("GRASS_PNGFILE", "%s"%pngfile)
     os.putenv("GRASS_WIDTH", "%i"%size)
     os.putenv("GRASS_HEIGHT", "%i"%size)
     os.putenv("GRASS_PNG_MAPPED", "%s"%mapped)
     module.run()

 def composite_images(files):
     pass

 def main():
     # Set the region
     modules.Module("g.region", rast="elevation", flags="p")

     for finish in parallel:
         if finish:
             print("*** Serial runs")
         else:
             print("*** Parallel runs")

         # Setup the modules
         rast   = modules.Module("d.rast", map="elevation", run_=False,
                                 quiet=True, finish_=False)
         vectB = modules.Module("d.vect", map="streams", width=1,
 color="blue",
                                 fcolor="aqua", type=["area","line"],
                                 run_=False, quiet=True, finish_=finish)
         vectA = modules.Module("d.vect", map="roadsmajor", width=2,
                                run_=False, quiet=True, finish_=finish)

         count = 0
         for driver in drivers:
             for mode in mmap_modes:
                 for size in sizes:
                     start = time.time()
                     count += 1
                     files = []
                     if mode == "TRUE":
                         rast_file = "rast.bmp"
                         vectA_file="vectA.bmp"
                         vectB_file="vectB.bmp"
                     else:
                         rast_file = "rast.png"
                         vectA_file="vectA.png"
                         vectB_file="vectB.png"

                     render_image(rast, driver=driver, pngfile=rast_file,
                                  size=size, mapped=mode)
                     render_image(vectA, driver=driver, pngfile=vectA_file,
                                  size=size, mapped=mode)
                     render_image(vectB, driver=driver, pngfile=vectB_file,
                                  size=size, mapped=mode)

                     files.append(rast_file)
                     files.append(vectA_file)
                     files.append(vectB_file)

                     # Wait for processes
                     rast.popen.wait()
                     vectA.popen.wait()
                     vectB.popen.wait()

                     # Composite the images
                     composite_images(files)

                     for file in files:
                         os.remove(file)

                     elapsed = (time.time() - start)
                     print("*** Run %i Driver=%s mmap=%s Size=%i
 time=%f"%(count,
 driver,
 mode,
 size,
 elapsed))

 main()
 }}}

 The result of the benchmark:

 {{{
 GRASS 7.0.svn (nc_spm_08_grass7):~/src > python display_bench.py
 projection: 99 (Lambert Conformal Conic)
 zone:       0
 datum:      nad83
 ellipsoid:  a=6378137 es=0.006694380022900787
 north:      228500
 south:      215000
 west:       630000
 east:       645000
 nsres:      10
 ewres:      10
 rows:       1350
 cols:       1500
 cells:      2025000
 *** Serial runs
 *** Run 1 Driver=png mmap=FALSE Size=1024 time=0.796055
 *** Run 2 Driver=png mmap=FALSE Size=4096 time=3.389201
 *** Run 3 Driver=png mmap=TRUE Size=1024 time=0.449877
 *** Run 4 Driver=png mmap=TRUE Size=4096 time=3.723065
 *** Run 5 Driver=cairo mmap=FALSE Size=1024 time=0.824797
 *** Run 6 Driver=cairo mmap=FALSE Size=4096 time=2.632125
 *** Run 7 Driver=cairo mmap=TRUE Size=1024 time=0.542321
 *** Run 8 Driver=cairo mmap=TRUE Size=4096 time=2.276822
 *** Parallel runs
 *** Run 1 Driver=png mmap=FALSE Size=1024 time=0.756147
 *** Run 2 Driver=png mmap=FALSE Size=4096 time=3.113990
 *** Run 3 Driver=png mmap=TRUE Size=1024 time=0.530959
 *** Run 4 Driver=png mmap=TRUE Size=4096 time=3.355732
 *** Run 5 Driver=cairo mmap=FALSE Size=1024 time=0.865963
 *** Run 6 Driver=cairo mmap=FALSE Size=4096 time=2.358270
 *** Run 7 Driver=cairo mmap=TRUE Size=1024 time=0.566976
 *** Run 8 Driver=cairo mmap=TRUE Size=4096 time=1.934245
 }}}

 There is no mmap() speed improvement for the PNG driver for large window
 sizes?
 I will investigate this further.

 [1] http://lists.freebsd.org/pipermail/freebsd-
 questions/2004-June/050371.html

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/2033#comment:4>
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