[mapserver-users] VRT memory usage (from C# Mapscript)
Frank Warmerdam
warmerdam at pobox.com
Thu Sep 2 09:01:18 PDT 2010
Lisa Gaudette wrote:
> I have an application using C# Mapscript where I've got a large number of
> .png tiles that wind up representing the same area but under different
> conditions. In order to avoid having huge numbers of duplicate .wld files,
> I'm using .vrt files to index the tiles.
>
> However, I've realized that each time a request is made for a different map,
> my memory usage increases. I can duplicate that with the following code,
> where the mapfiles contain .vrt layers but it's fine with a .shp tileindex.
> This happens even when the 2nd map represents a much smaller area with many
> fewer tiles than the first.
Lisa,
In recent versions of MapServer an effort is made to keep GDAL files open
between render requests for raster layers with a single file as opposed
to a tile index. I wonder if you might be running into a problem with
this behavior in a long running mapscript script. I don't understand
the whole context in which you are operating so I could be off base. But
you might consider adding:
PROCESSING "CLOSE_CONNECTION=NORMAL"
to your raster layer to force the files to be closed at the end of a render.
Best regards,
--
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush | Geospatial Programmer for Rent
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