Hi Paul, Thanks for the tips, I forgot about trying from the command line and the apache log :) Anyway, I found out the problem was to do with libpq.so.4 (which is a Postgres library) not being found. My colleague had upgraded Postgres, so it wasn't me that broke MapServer afterall !
The new libpq library is libpq.so.5. Recompiling MapServer did not solve the problem, so I just symlinked libpq.so.4 to libpq.so.5 . Problem solved. Now to track down the performance issues! Thanks, John >>> "Paul Ramsey" <[EMAIL PROTECTED]> 18/09/08 1:09 AM >>> Pull out your command-line, you probably have a linking library problem, and mapserv is just dying unceremoniously. So first: can you just run "mapserv" on the command line. If not, what's the error? is it instructive? Second, if just a plain "mapserv" runs, what happens when you feed it your workload? the trick is to use the mysterious "QUERY_STRING" commandline parameter, thusly: ./mapserv "QUERY_STRING=map=/your/map.map&layers=yourlayers&etc" This runs mapserv in pretend CGI mode, without having a web server in the way, very handy for debugging. P. PS - I just realized, usually you can see the error in the apache error_log, skipping all this tedious command-line stuff. On Wed, Sep 17, 2008 at 3:00 PM, John Westwood <[EMAIL PROTECTED]> wrote: > 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! > > Thanks, > > John > > >>>> "Paul Ramsey" <[EMAIL PROTECTED]> 17/09/08 5:15 PM >>> > 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 <[EMAIL PROTECTED]> 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 > > _______________________________________________ mapserver-users mailing list mapserver-users@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/mapserver-users
