performance issues

[Bill Binko]

> 
> Normally when I run into this sort of problem, I would
> build MapServer in debug mode, and run it in gdb.
> Then hit "cntl-c" a few times during the run and get
> a traceback to see what is going on.  This crude sampling
> technique can often identify especially major performance
> bottlenecks.
> 
> If the statistics on msDrawMap() are accurate then the
> bulk of the delay must be somewhere else.  Perhaps the
> compression of the PNG (though it does not seem
> especially large) or some sort of preprocessing (getting
> projections during .map processing?)
> 

If shp2img is causing the same issue, you can use qprof to determine the 
location of the performance problem.  I tried to get it to work on 
mapserv, but there is some dynamic loading (of gd) that causes it to fail.

QProf (from HP - http://www.hpl.hp.com/research/linux/qprof/ ) is an 
outstanding tool for this.  I was considering posting a note to the board 
about it, but was hung up on getting mapserv to work w/it.

Basically, you install it (very simple build etc.) and it has a shared 
library that is loaded through LD_PRELOAD (which I didn't even know 
about).  That library samples your app and give a basic profile after each 
command is executed.  If your apps/libs are built with debugging (-g) it 
helps, but it is not necessary for basic performance.  There is no need to 
build w/ profiling (-p or -pg) and you can run it on apps you didn't build 
at all!

I'd be happy to help you getit setup and running.

Bill

bill.binko at mapshine.com