On Fri, 2 Oct 2020 at 00:53, René-Luc Dhont <rldh...@gmail.com> wrote: > > Hi devs, > > A customer found that reading a lightweight GeoTIFF takes 1 second in > QGIS Server needs less than 200 milliseconds. > > With timer I found somethings strange around the virtual > QgsRasterInterface block method and it's reimplation in QgsGdalProvider. > Here is part of my logs: > > ../src/core/raster/qgsrasteriterator.cpp:87 : > (readNextRasterPartInternal) [2ms] Entered > ../src/core/providers/gdal/qgsgdalprovider.cpp:2641 : (initIfNeeded) > [1ms] GdalDataset opened > ../src/core/providers/gdal/qgsgdalprovider.cpp:317 : (crsFromWkt) [0ms] > +proj=aea +lat_1=43 +lat_2=62 +lat_0=30 +lon_0=-30 +x_0=0 +y_0=0 > +datum=WGS84 +units=m +no_defs > ../src/core/providers/gdal/qgsgdalprovider.cpp:2836 : (initBaseDataset) > [0ms] GDALGetRasterNoDataValue = -3.4e+38 > ../src/core/providers/gdal/qgsgdalprovider.cpp:647 : (block) [10ms] > QgsGdalProvider::block > ../src/core/providers/gdal/qgsgdalprovider.cpp:718 : (readBlock) [0ms] > QgsGdalProvider::readBlock > ../src/core/providers/gdal/qgsgdalprovider.cpp:965 : (readBlock) [2ms] > QgsGdalProvider::readBlock completed in (seconds): 0.002 > ../src/core/providers/gdal/qgsgdalprovider.cpp:684 : (block) [0ms] > QgsGdalProvider::block completed in (seconds): 0.002 > ../src/core/raster/qgsrasteriterator.cpp:137 : > (readNextRasterPartInternal) [643ms] Raster iterator read next block > completed in (seconds): 0.656 > ../src/core/raster/qgsrasteriterator.cpp:87 : > (readNextRasterPartInternal) [3ms] Entered > ../src/core/providers/gdal/qgsgdalprovider.cpp:647 : (block) [6ms] > QgsGdalProvider::block > ../src/core/providers/gdal/qgsgdalprovider.cpp:718 : (readBlock) [0ms] > QgsGdalProvider::readBlock > ../src/core/providers/gdal/qgsgdalprovider.cpp:965 : (readBlock) [0ms] > QgsGdalProvider::readBlock completed in (seconds): 0 > ../src/core/providers/gdal/qgsgdalprovider.cpp:684 : (block) [0ms] > QgsGdalProvider::block completed in (seconds): 0 > ../src/core/raster/qgsrasteriterator.cpp:137 : > (readNextRasterPartInternal) [283ms] Raster iterator read next block > completed in (seconds): 0.289 > ../src/core/raster/qgsrasteriterator.cpp:87 : > (readNextRasterPartInternal) [0ms] Entered > > > The qgsrasterinterator.cpp ligne 130 [1] tooks almost 300 times longer > than it's reimplementation. > > Do you know a way to enhance this ?
I'd caution against reading too much into the debug output timings. My suggestion is to re-run the tests using hotspot (https://github.com/KDAB/hotspot) as this will give much more useful information about the bottlenecks. Nyall _______________________________________________ QGIS-Developer mailing list QGIS-Developer@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-developer Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-developer
