[mapserver-users] Comparing cgi and fcgi for serving aerial images

Rahkonen Jukka Jukka.Rahkonen at mmmtike.fi
Fri Dec 18 04:32:03 EST 2009


I made some tests by letting JMeter run a few thousand WMS GetMap
requests with varying BBOX and WIDTH and HEIGHT parameter.  I tested
three alternatives:
 
MS4W 2.2.8 and Mapserver 5.2.1
MS4W 3.0 beta 7 and Mapserver 5.6.0 as cgi
MS4W 3.0 beta 7 and Mapserver 5.6.0 a fcgi
 
Server is Windows 2003 server with 8 cores and fast disks. I configured
JMeter to use 20 threads
 
I feel I was able to get fcgi running by following the instructiuons of
MS4W README_INSTALL document.  I believe it is convinced by a) calls
addressed to  /fcgi-bin/mapserv.exe work and b) after receiving an image
from WMS service the process remains on the server for some time.
However, all these three alternatives are giving me about the same speed
that is  5 images per second or 500 KB/sec with jpeg output.  Bandwidth
is not the limiting factor because with 24-bit png output I get a
throughput of 4400 KB/sec.  It looks like I am having some  base load in
my system that takes about 150 milliseconds per each successful WMS
request and using fcgi does not help in my case.
 
Can anybody suggest why my server is so much slower than the one used in
Mapserver/Geoserver shootout
http://www.slideshare.net/gatewaygeomatics.com/wms-performance-shootout
and why I do not get any advantage from using Fast-CGI?  Could it be
because my tileindex shapefile is rather large with more than 11000
polygons?  Images themselves are processed in a standard Mapserver way
and they are uncompressed, tiled geotiffs with external uncompressed
overviews.  Some evidence about tileindex handling eating time is that I
can get double speed with 10 images per second from a single ecw file
but this test is not very comparable because my ecw file is black and
white and not 3-channel as my geotiff layer.
 
-Jukka Rahkonen-
 
 
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