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<p>you need to include in your QUERY_STRING=MAP=....&</p>
<p>it is probably hard coded in the fcgi config.</p>
<p>-Steve W<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 7/22/2020 7:15 PM, English Paul
wrote:<br>
</div>
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cite="mid:709E4A73-CB43-4E23-9D9E-87CA24B698E8@vaisala.com">
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<p>So you have a complex historical "mess" and its not clear
where the performance issue is. So you need to divide the
problem into small problems that you can verify are or are not
contributing. I would start with something like this:</p>
<p>Thank you – I would not have thought to try it outside of CGI
entirely!</p>
<p>Take one slow image request and try that as cgi or cli and
not fcgi and turn on debugging.</p>
<p> - copy and rename you mapfile so it doesn't mess with the
production requests</p>
<p>Not a major worry in this case – I’m working in an entirely
dev environment. I did make backup copies though!</p>
<p> - turn on the debugging and send it to stderr in the debug
mapfile</p>
<p> - you can manually run that image request from the
commandline like:</p>
<p>if mapserv is not in your path you might need to find it and
your the path to it below</p>
<p>mapserv -nh QUERY_STRING="everything after the ? in the
original query" >junk.png 2>error.txt</p>
<p>-nh suppresses headers from being output before the image
data</p>
<p>error.txt will be stderr output and should contain the debug
messages</p>
<p>I couldn’t quite get there – which this is what I ended up
running:</p>
<p># /usr/libexec/mapserv -nh
QUERY_STRING="FORMAT=image%2Fpng&LAYERS=winter1km_5min&TRANSPARENT=TRUE&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap&STYLES=&TIME=2020-07-22T22%3A30%3A00Z&SRS=EPSG%3A900913&BBOX=-11584184.507886,4070118.8849183,-11271098.44003,4383204.9527744&WIDTH=256&HEIGHT=256"
> junk.png 2>error.txt</p>
<p>I first tried it with our current map file(s), and then with
MS_ERRORFILE set to stderr and DEBUG set to 5, in both cases,
I got an empty error.txt, and the following in junk.png:</p>
<p>Content-type: text/html</p>
<p> </p>
<p><HTML></p>
<p><HEAD><TITLE>MapServer
Message</TITLE></HEAD></p>
<p><!-- MapServer version 6.0.1 OUTPUT=GIF OUTPUT=PNG
OUTPUT=JPEG OUTPUT=KML SUPPORTS=PROJ SUPPORTS=AGG
SUPPORTS=CAIRO SUPPORTS=FREETYPE</p>
<p>SUPPORTS=ICONV SUPPORTS=FRIBIDI SUPPORTS=WMS_SERVER
SUPPORTS=WMS_CLIENT SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT
SUPPORTS=WCS_SERVER SU</p>
<p>PPORTS=SOS_SERVER SUPPORTS=FASTCGI SUPPORTS=THREADS
SUPPORTS=GEOS INPUT=POSTGIS INPUT=OGR INPUT=GDAL
INPUT=SHAPEFILE --></p>
<p><BODY BGCOLOR="#FFFFFF"></p>
<p>loadMap(): Web application error. CGI variable
"map" is not set.</p>
<p></BODY></HTML></p>
<p>I noticed that if I ran it with just -nh, I get the
following:</p>
<p>#/usr/libexec/mapserv -nh</p>
<p>This script can only be used to decode form results and</p>
<p>should be initiated as a CGI process via a httpd server.</p>
<p>So maybe this older version just really doesn’t want to be
run on the CLI? Or maybe I’m messing up the QUERY_STRING, or
need to set the CGI variable to something as the junk.png
output suggests?</p>
<p>Thanks again and thanks SO MUCH for the super quick reply!!</p>
<p>Paul</p>
<p> </p>
<div>
<p class="MsoNormal">On 7/22/2020 1:47 PM, English Paul wrote:</p>
</div>
<blockquote>
<div>
<p class="MsoNormal">
Hi,</p>
<p class="MsoNormal">
Newbie here, just got a work assignment to look into
some performance issues with
mapserver-6.0.1-3_0.el6.x86_64 – specifically, at one
time, it rendered radar images very fast, then it degraded
and seemed to consume a lot more CPU. So – the EC2
instance side was upgraded significantly – and it still
performs badly and uses a lot of CPU. It also seems to be
getting slowly worse over time (days/months, not
seconds/minutes). I asked this on IRC, but it looks like
email might be a better route.</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
During all of this, the same mapserver instance renders
satellite images quickly. These seem to be a similar, or
in some cases larger size png to start with, rendered onto
the same final map/size.</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
So – the obvious answer is that it isn’t using the CPU
to render/re-render, but rather spending it on something
else – I/O most likely – eg: a network request, disk I/O,
SQL query?</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
The previous person working on it tried turning on debug
at various levels – but unfortunately that made it even
slower, making it tricky to answer “what is making it slow
when debug is turned off?”</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
My first instinct was to try an strace and nothing was
obvious. Next up – a flame graph from strace, and/or
trying dtrace – but my understanding is that dtrace is a
little weak on RHEL/CentOS/Amazon Linux 6.0 *<b>and</b>*
I’m not particularly good at that. Also, we’re using fcgi,
so attaching to the correct process is a bit tricky.</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
My next instinct was to look at release notes and see if
the current stable has anything fixes/improvements that
directly address this – there aren’t any that are obvious
to my eyes, but you developers have been busy! So many
things! Including some performance fixes and one
“significant” performance fix.</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
Current config file:</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
AddHandler fcgid-script fcgi</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
FcgidIPCDir /var/run/mod_fcgid</p>
<p class="MsoNormal">
FcgidProcessTableFile /var/run/mod_fcgid/fcgid_shm</p>
<p class="MsoNormal">
FcgidMaxProcesses 10</p>
<p class="MsoNormal">
FcgidMaxProcessesPerClass 10</p>
<p class="MsoNormal">
FcgidMaxRequestInMem 196608</p>
<p class="MsoNormal">
FcgidInitialEnv PROJ_LIB /usr/share/proj</p>
<p class="MsoNormal">
FcgidInitialEnv LD_LIBRARY_PATH
"/usr/local/lib:/usr/pgsql-9.1/lib"</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
So – suggestions for my next move? I currently plan to
take a quick swing at building 7.6 for RHEL 6.0, knowing
there might be old libraries and whatnot that make that a
non-starter. Of course – we’ve got other infra running on
this same instance, so upgrading everything is a much
bigger task.</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
Strace flame graph? </p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
Stretch and try dtrace?</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
A better way to use debug?</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
Something else I’m missing – eg: differences between the
image types that make them perform so differently?
</p>
<p class="MsoNormal">
</p>
<p class="MsoNormal">
Thanks,</p>
<p class="MsoNormal">
Paul</p>
</div>
<p class="MsoNormal"><br>
<br>
</p>
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