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

John Westwood John.Westwood at port.ac.uk
Wed Sep 17 18:00:34 EDT 2008

Hi Paul,

Thanks for the useful information. The performance is pretty terrible, so I will have to do some more investigating. The MapServer executable almost completely maxes out two cores and it can take 30 seconds or more to fetch all the tiles for a particular view. I do connect to Postgres to fetch map metadata and I pull the info from MapServer using WFS. Perhaps this is causing a problem.

One large problem. I tried going back to my old MapServer without the FastCGI and I commented out my MapServer configuration lines in the mod_fcgid.conf file (and restarted the server). Unfortunately, this too now no longer works and gives the same error:

The server encountered an internal error and was unable to complete your request
Error message: Premature end of script headers: mapserv

I really need to fix this! Aaaaaarghhhh!



>>> "Paul Ramsey" <pramsey at cleverelephant.ca> 17/09/08 5:15 PM >>>

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.


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