One of the interesting things Andrea contributed to this conversation was benchmarks.
The conversation goes outside of the SimpleFeatureCollection proposal and should involve Ben and anyone interested in rendering a generic FeatureCollection. Andrea since it is clear that there is a performance difference between SimpleFeature and Feature (and that the renderer is *not* the place to pay a performance difference!) how should we go about rendering generic feature content? The obvious one for me is to perform an instance of check (once SimpleFeatureCollection is introduced); making sure to perform the instanceof check outside of any FeatureIterator loop. The same solution can be done with a visitor - break out a FeatureVisitor and SimpleFeatureVisitor and perform the check once in the feature collection accepts method; the renderer is still on the hook however for implementing the inside of the loop twice in order to take advantage of any performance differences :-( Is there another way we could do this one? Jody >> It is not really an issue until we get more generic feature collections; >> there is a small number of places where SimpleFeature was assumed in the >> rendering code. >> With respect to performance I think that if SimpleFeatures are passed in the >> performance will be the same? > > Performance will definitely not be the same. > SimpleFeatureImpl.getAttribute(name) returns the actual value, > Feature.getProperty(name) returns a "Property" object, a > wrapper around the value which has to be built. > The SLD handling code uses property > accessors, which are slower than direct access but make the code > portable. > > I made a little benchmark for different property access styles > (attached): > - using the simple feature getAttribute() > - using Feature getProperty().getValue() > - dynamically looking up property accessors > - caching property accessors > > The timings on Java 6 are: > > Building features... > Building features: 2.759 > Testing SimpleFeature access... > Direct access: 0.081 > Testing Feature access... > Feature access: 0.468 > Testing property accessors... > Property accessors: 2.438 > Testing cached accessors... > Cached property accessors: 0.105 > > As you can see using Feature is 8 times slower, > and using dynamically found accessors takes as much time > as actually building the features. > The only way to get decent performance is to use > accessors and reuse them. > I can have a look into doing that. > > Btw, a curiosity: in this test the difference between > Java 5 and Java 6 is massive. Look at the results > with Java 1.5.0_22: > > Building features... > Building features: 18.702 > Testing SimpleFeature access... > Direct access: 0.085 > Testing Feature access... > Feature access: 0.474 > Testing property accessors... > Property accessors: 1.898 > Testing cached accessors... > Cached property accessors: 0.141 > > With a Java 7 recent build the results are actually odd > in another way: > > Building features... > Building features: 2.131 > Testing SimpleFeature access... > Direct access: 0.138 > Testing Feature access... > Feature access: 1.008 > Testing property accessors... > Property accessors: 1.524 > Testing cached accessors... > Cached property accessors: 0.091 > > As you can see... cached property accessors are fast than direct > access??? :-) And Feature access is actually twice as slow as Java 6, > ugh. Not sure what to make of the Java 7 numbers, but it's also > just a preview build. > > >>> To sum up, maybe clean up a little the proposal. I feel good about the >>> change, I should just get some time to actually try to apply the patch >>> (will try to do that soon) >> Thanks Andrea; I would like the feedback of yourself and Micheal if possible. > > Basic feedback is that I prefer to have everything happen on trunk only. > This will make for a few months of hard to port forward patches btw... > probably late July would have been a better time for this patch. > However I also understand that if we delay you'll have to start over. > > Cheers > Andrea > > -- > Andrea Aime > OpenGeo - http://opengeo.org > Expert service straight from the developers. > import java.util.ArrayList; > import java.util.List; > > import org.geotools.feature.simple.SimpleFeatureBuilder; > import org.geotools.feature.simple.SimpleFeatureTypeBuilder; > import org.geotools.filter.expression.PropertyAccessor; > import org.geotools.filter.expression.PropertyAccessors; > import org.opengis.feature.Feature; > import org.opengis.feature.simple.SimpleFeature; > import org.opengis.feature.simple.SimpleFeatureType; > > import com.vividsolutions.jts.geom.Polygon; > import com.vividsolutions.jts.io.WKTReader; > > > public class PropertyAccessTest { > > public static void main(String[] args) throws Exception { > SimpleFeatureTypeBuilder ftb = new SimpleFeatureTypeBuilder(); > ftb.add("geom", Polygon.class, "EPSG:4326"); > ftb.add("name", String.class); > ftb.add("persons", Long.class); > ftb.setName("testFeature"); > SimpleFeatureType ft = ftb.buildFeatureType(); > > // building features > System.out.println("Building features..."); > long start = System.currentTimeMillis(); > List features = new ArrayList(); > SimpleFeatureBuilder fb = new SimpleFeatureBuilder(ft); > Polygon geom = (Polygon) new WKTReader().read("POLYGON((0 0, 0 10, 10 > 10, 10 0, 0 0))"); > for (int i = 0; i < 1000000; i++) { > fb.add(geom); > fb.add("feature" + i); > fb.add(i); > features.add(fb.buildFeature(null)); > } > long end = System.currentTimeMillis(); > System.out.println("Building features: " + (end - start) / 1000.0); > > System.out.println("Testing SimpleFeature access..."); > start = System.currentTimeMillis(); > testDirectAccess(features); > end = System.currentTimeMillis(); > System.out.println("Direct access: " + (end - start) / 1000.0); > > System.out.println("Testing Feature access..."); > start = System.currentTimeMillis(); > testFeatureAccess(features); > end = System.currentTimeMillis(); > System.out.println("Feature access: " + (end - start) / 1000.0); > > System.out.println("Testing property accessors..."); > start = System.currentTimeMillis(); > testAccessors(features); > end = System.currentTimeMillis(); > System.out.println("Property accessors: " + (end - start) / 1000.0); > > System.out.println("Testing cached accessors..."); > start = System.currentTimeMillis(); > testCachedAccessors(features); > end = System.currentTimeMillis(); > System.out.println("Cached property accessors: " + (end - start) / > 1000.0); > } > > private static void testFeatureAccess(List<Feature> features) { > for (Feature feature : features) { > feature.getProperty("geom").getValue(); > feature.getProperty("name").getValue(); > feature.getProperty("persons").getValue(); > } > } > > private static void testDirectAccess(List<SimpleFeature> features) { > for (SimpleFeature feature : features) { > feature.getAttribute("geom"); > feature.getAttribute("name"); > feature.getAttribute("persons"); > } > } > > private static void testAccessors(List features) { > for (Object feature : features) { > PropertyAccessors.findPropertyAccessor(feature, "geom", > Polygon.class, null).get(feature, "geom", Polygon.class); > PropertyAccessors.findPropertyAccessor(feature, "name", > String.class, null).get(feature, "geom", String.class); > PropertyAccessors.findPropertyAccessor(feature, "persons", > Integer.class, null).get(feature, "geom", Integer.class); > } > } > > private static void testCachedAccessors(List features) { > PropertyAccessor geomAccessor = > PropertyAccessors.findPropertyAccessor(features.get(0), "geom", > Polygon.class, null); > PropertyAccessor nameAccessor = > PropertyAccessors.findPropertyAccessor(features.get(0), "name", String.class, > null); > PropertyAccessor personsAccessor = > PropertyAccessors.findPropertyAccessor(features.get(0), "persons", > Integer.class, null); > for (Object feature : features) { > geomAccessor.get(feature, "geom", Polygon.class); > nameAccessor.get(feature, "geom", String.class); > personsAccessor.get(feature, "geom", Integer.class); > } > } > } ------------------------------------------------------------------------------ _______________________________________________ Geotools-devel mailing list Geotools-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/geotools-devel
