[Chameleon] Performance measuring question

Delfos, Jacob jacob.delfos at maunsell.com
Wed Apr 12 19:46:38 EDT 2006


It depends very much on your hardware, but I find rasters are mostly the
culprit (unless your vector layers are more than 20MB) on systems that
have normal hard-drives (IDE or ATA, not SCSI). People running server
hardware get better performance for TIF's, because their harddisks are
very fast, and they like to reduce load on the CPU. However, I find that
on 'normal' machines with 1 harddisk the performance of ECW's is
significantly better. If I were you I'd experiment with compressing your
TIF's into 1 ECW file, and see what happens. Your image will probably be
only 30-50MB. Particularly in a situation where all 12 TIF's need to be
drawn, you may be better off with one ECW file. We get great redrawing
times even with 2.5GB ecw's on a normal harddisk. Obviously this will go
down as users increase, because of increased loan on the CPU.



> -----Original Message-----
> From: chameleon-bounces at lists.maptools.org 
> [mailto:chameleon-bounces at lists.maptools.org] On Behalf Of 
> Gambin Dejan
> Sent: 12 April 2006 18:14
> To: chameleon at lists.maptools.org
> Subject: [Chameleon] Performance measuring question
> Hi list,
> I have finally finished my first serious Chameleon application. It is
> working very good, but I would like to see if there are possibly some
> performance problems that can be solved because I am experiencing slow
> map drawing sometimes (when zooming in)....I'll try to be 
> more detailed:
> My current application has several layers of which the one is raster
> layer defined over 12 tif files (40MB each) that I joined using
> tileindex..I have also internally tiled and created internal overviews
> on each of the tif files...
> Next I have the main layer, that is roads...it is a LINE 
> shape that has
> about 1MB (and its dbf has only 73KB with 247 records). This layer is
> also labeled with two lines, one is overlayed over the other...
> My questions are:
> 1. Since the data I presented shouldn't be "heavy" and 
> assuming testing
> on my localhost - what can be the main reason for sometimes slow map
> drawing? I am using JSAPI mode
> 2. How to debug it on Windows? How can I see what is causing this
> slowness? I would like to know if hardware is the reason 
> (disk subsystem
> or RAM) or the application...
> 3. I have created my own buttons and icons...maybe they are 
> "heavy"? Are
> they somehow cached? What about the caching anyway?
> Any suggestions are welcome
> Thanks very much
> regards, dejan
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