performance slows down when compiled with gdal

Ed McNierney ed at TOPOZONE.COM
Wed Jun 7 13:32:48 EDT 2006


Holger -

The times you see also do not include the time required to load, parse,
and "set up" the map file.  However, your map file seems quite plain and
there's nothing in there that seems like it would require much work.

You could try to measure the map file load time, but you'll need to make
some modifications and recompile MapServer to do that - let me know if
you want some advice on doing that.

Do you happen to have an exceptionally large EPSG text file, or is it
stored in a hard-to-access (i.e. slow) location?  Your EPSG projection
definitions need to be looked up in that file, and a very large or slow
file would slow things down.  I cannot imagine, however, how that could
possibly cause 3 seconds of delay.

It might be helpful to look at the timestamps in the log file to see if
the extra three seconds are coming BEFORE the map drawing events, or
AFTER them.  That would at least help indicate whether it's a
startup/mapfile problem or an output file saving problem.

	- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
ed at topozone.com
(978) 251-4242 

-----Original Message-----
From: UMN MapServer Users List [mailto:MAPSERVER-USERS at LISTS.UMN.EDU] On
Behalf Of Frank Warmerdam
Sent: Wednesday, June 07, 2006 9:36 AM
To: MAPSERVER-USERS at LISTS.UMN.EDU
Subject: Re: [UMN_MAPSERVER-USERS] performance slows down when compiled
with gdal

porath at web.de wrote:
> Hi Frank,
> 
> i turned on debugging and found the following entries for a request:
> [Wed Jun  7 11:04:17 2006].332715 msDrawMap(): Layer 16 (huek-b256), 
> 0.040s [Wed Jun  7 11:04:17 2006].333253 msDrawMap(): Drawing Label 
> Cache, 0.000s [Wed Jun  7 11:04:17 2006].333382 msDrawMap() total 
> time: 0.045s
> 
> This seems to be very fast. The Apache Log reports 3 seconds for the
same request.
> 
> Does this mean that it is still a startup issue? 

Holger,

Well, it indicates it isn't a rendering problem.  The above times don't
include the time to save the file to png/jpeg/gif so it could be
spending an inordinate amount of time doing that for some reason.  But I
still suspect some odd initialization things is taking a lot of time.

If I had direct access to the system I would try reproducing the exact
mapserv request and invoking it at the commandline.  First as your
regular user, and then in an environment as close a possible to
Apache's.  I would next likely add some extra timing debug messages to
track time from mapserv startup to shutdown.  That would help isolate if
the delay is before entering main or somewhere later.

Best regards,
-- 
---------------------------------------+--------------------------------
---------------------------------------+------
I set the clouds in motion - turn up   | Frank Warmerdam,
warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGF,
http://osgeo.org



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