[gradsusr] Performance issue when working with multiple files on GrADS 2.1

[Brian Gaze]

Hi,

When working concurrently with multiple grib2 files I'm encountering a
performance issue. I initially thought this was caused by the grib2 cache
but now wonder if it is related to the metafile buffer.

The sample script below helps to explain. Scenario is....

1) Open all files
2) Outer loop where latitude and longitude for plot are set
3) Inner loop through all open files plotting 2 variables from each one for
the latitude and longitude currently set
4) Write output to an image file
5) Iterate

If I reduce the filenumber count to be lower than 13 OR only plot 1
variable the image files are generated quickly, approx 1.5 per second.

If I leave the filenumber count as it is and plot the 2 variables the plot
plot is very slow taking approx 50 seconds to be written to the file system.



*Open files 1 to 22
'open file00.ctl'
'open file01.ctl'
'open filexx.ctl'


while(b<60)

filenumber=1
while (filenumber<23)
'set dfile ' %filenumber
'd var1'
'd var2'
filenumber=filenumber+1
endwhile

op = ' C:\'%imagefilename% '.png png x800 y600'
'gxprint ' %op ' white'

B=B+1
endwhile


When running the .gs I've tried using the -m NNN option to increase the
metafile buffer size (e.g. to 3000000) but this doesn't seem to make any
difference.

Any ideas??

Thanks

Brian
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