[mapserver-users] How to make MapServer WMS super fast?

[Frank Warmerdam]

Rahkonen Jukka wrote:
> Hi,
>  
> Are there any effective tricks for making MapServer to Top-Fuel 
> class?  We have now a typical ms4w installation on a rather good server 
> platform with SCSI drives and 2 four-core processors running on Windows 
> 2003 server. Our images are tiled, uncompressed geotiffs with overviews, 
> vector sample data set is shapefile with shptree index.  I have a 
> shortened epsg file and my mapfile is extra short. Bandwith is not the 
> limit. We are getting out now about 450 orthoimage pictures per 
> minute (size 500 by 500 pixels) and 550 pictures from the vector layer 
> in png24 image format.  I consider that rather good, but we are required 
> to reach 20 images per second, thus 1200 images per minute or 0.05 
> seconds per image.  I wonder if anybody has tuned MapServer that far.
>  
> I am willing to try however exotic solutions to reach the 20 WMS output 
> images/second goal if somebody could suggest me what to try next.  In 
> our system there seems to be about 0.1 second ballast with WMS getMap 
> requests and I cannot get any faster response even if I try with on 
> empty data layer with nothing to render.  Have anybody tried to keep 
> mapfile,  epsg-file or even tileindex files in RAM drive? 
>  
> Having about 20 parallel users seems to be optimal for our server and if 
> I drive just WMS getCapabilities request against my mapfile I can get 
> about 1300 responses per minute.  That leads me to think that 1200 
> rendered images per minute might be possible to reach with optimal set-up.

Jukka,

I'd suggest you come to the TO Code Sprint and help us fine tune performance!

   http://wiki.osgeo.org/wiki/Toronto_Code_Sprint_2009

More seriously, I have had the impression that some of the "everything
but the kitchen sink" distributions like MS4W, FWTools and OSGeo4W have
somewhat significant startup overhead - possibly due to the number of
DLLs being loaded at startup.  You might look into a custom building
a "lite" version of mapserver and see if that helps.

As someone else noted, fastcgi will also let you skip such startup
costs on a per request basis.

But honestly, why not just buy another damn server?  Isn't your time
worth something!

Best regards,
-- 
---------------------------------------+--------------------------------------
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