Hello List:

I am developing a QGIS plug-in for the purpose of running simulation models for 
unique land units, as represented by polygons in a polygon shapefile.  
Essentially, the plug-in uses spatial information in the polygon layer to write 
a simulation model input file.  It then uses Python's 'subprocess' module to 
call the model executable and run the simulation.  It then reads an output file 
generated by the model, sets the polygon shapefile to be editable, changes some 
attributes based on the model output, and then commits those changes.  Then 
repeating this in a loop for each feature in the polygon shapefile.

I've also included an optimization routine for the purpose of model 
calibration.  This essentially means doing the above procedures repeatedly tens 
or hundreds of thousands of times.   After each model simulation, the updated 
'simulated' attribute values are compared with other attributes that contain 
'observed' data.  The optimization then repeatedly adjusts the model parameters 
until simulated and observed data are in best agreement.

This process can take many hours or days, while I am repeatedly editing the 
shapefile and commiting the edits.  However, I am not adding or removing any 
features or attributes.  Problem is the memory slowly creeps up and if the 
optimization takes too long, I'll run out of memory and QGIS will crash. I 
notice that if my optimization routine does finish, I can completely shut down 
my plugin's dialog window, but the memory usage remains high.  This makes me 
think the problem is not in my plug-in.  Any ideas for me?

Thanks,
Kelly

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Kelly Robert Thorp, Ph.D., P.E.
Research Agricultural Engineer
USDA-ARS
U.S. Arid Land Agricultural Research Center
21881 N Cardon Lane
Maricopa, AZ  85138
520-316-6375 (Phone)
520-316-6330 (Fax)
[email protected]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~





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