On 28/03/2010, at 8:30 PM, Andrea Aime wrote: > Hi, > took some time to look into vector data in memory > caching to try and provide some response to those > users that still find the rendering demos too slow. > > First I've tried out the gt-caching module, with mixed > success. Even allowing the StreamingFeatureCache to > fully cache in memory the data the performance compared > to a local shapefile does not improve, it's actually > more or less the same. > When allowing the cache to just keep in memory half of the > features the performance drops very significantly, > putting the cache at 1/3 of the performance of the > shapefile data store when showing all of the data, > and almost the same when very zoomed in. > Anyways, this has not been bad, found a couple of bugs > I could provide fixes for: > http://jira.codehaus.org/browse/GEOT-3012 > http://jira.codehaus.org/browse/GEOT-3013 > > I've then looked into my old "cache everything in > a spatial index" approach, getting more or less the > same performance as the shapefile data store.
There is a post on gvSig mobile about just drawing from the spatial index (I assume at higher scales only): - http://gvsigmobileonopenmoko.wordpress.com/2010/02/27/large-shapefiles-on-small-screens-using-a-drawable-spatial-index/ > After a bit o profiling found that the DefaultFeatureCollection > was the cause of such disappointing results and > rolled my own, making the attached caching feature > source almost twice as fast as the shapefile > data store. > > It's still a toy, but for people that have small amounts > of data can be an answer. > Micheal, I don't feel like putting it in the official > gt2 modules, but I think it would make a nice addition > to the example one as a simple way to cache vector data? > Maybe someone could pick it up and improve it. > > Ah, finally, I've looked into the caching module and I have > the impression it's possible to create a more compact (in terms > of code), faster, self adapting cache (as in, the current one > requires the user to hand tune the grid size to work properly). > If anyone is interested I have put down on paper some > design ideas I think I better be interested; running some uDig 1.2 benchmarks against uDig 1.1.1 was not pretty; going to try again formally and make a bug report :-P Jody ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Geotools-devel mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/geotools-devel
