[mapserver-users] Using Fast CGI with MapServer to alleviate poorperformance

[Jim Klassen]

I have found there is a fairly large overhead inherent in the HTTP request (per tile) especially if the network round trip times are an issue. Using HTTP keep-alive helped a lot with this.

Awhile ago we did some tests at the city when we were looking to go to a tiled interface. What we found was along the lines of a 100x100px tile request takes much more than 1/4 of the time of a 200x200px request so the overall map load time was slowed by using more tiles when getting the tiles from mapserver. This would probably be different if we had used a tilecache. In the end we found not tiling (a.k.a. 1 tile per map) worked best for us from a speed/flexibility focus.

JimK

>>> "Paul Ramsey" <pramsey at cleverelephant.ca> 09/17/08 11:14 AM >>>
John,

The idea that CGI is naturally a much slower situation than a
long-running process is a bit of a red herring in the case of
Mapserver, and I say that as someone who is anal retentive about these
things.  Unless your Mapserver installation has some naturally latent
components (database connections, primarily) you'll find that moving
from CGI to FastCGI is worth about 15ms per request.

On Wed, Sep 17, 2008 at 8:40 AM, John Westwood <John.Westwood at port.ac.uk> wrote:

> The reason I am trying to get MapServer to work with fast_cgi is because I am experiencing poor performance with OpenLayers. I believe that OpenLayers starts a new MapServer instance for each tile request, thus causing an unnecessary overhead. Am I correct?

Yes and no. If you are experiencing noticeably poor performance (you
can actually *see* it being slow) the only place that the CGI overhead
could be the cause is if you're connecting to Oracle or SDE for some
of your layers. If that's not the case, look elsewhere first, the very
small gains you will receive from moving to FastCGI will not change
your underlying problem.

Paul
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