[mapserver-users] mapserver defunct

[Stephen Woodbridge]

Wim,

I'm not sure I have any magic bullet for this problem, because I'm not 
sure what is causing it. If this was my project, I would tackle it like 
this:

1. alert people we have a problem that might impact the release date if 
you have not already done that
2. divide the problem to try and localize what is causing it

a. do the tiles that fail, always fail? this points at a potential 
mapserver related issue as opposed to a load issue
a.1 have you turned on mapfile DEBUG output? can you identify the layer
a.2 you can get some maybe useful output from:

strace /path/to/mapserv QUERY_STRING='<url arguments>'

gdb /path/to/mapserv
run QUERY_STRING='<url arguments>'
where
quit

valgrind /path/to/mapserv QUERY_STRING='<url arguments>'

a.3 you can run it with shp2img ...

b. is it fastcgi, do you see the same problem if you build it as cgi
c. is it lighttpd, do you see the same problem if you run it with apache 
fastcgi? what about apache cgi?

Intermittent problems are the hardest to diagnose because they often are 
not reproducable in a debuging environment. We might be able to help you 
with more information.

I have done a lot of load testing on various versions of mapserver and 
tiled all of US and Canada about 4-5 different times using mapserver. I 
have not used FastCGI/Lighty and lighttpd, so I'm not sure about what 
influence that might have on the problem.

Hope this gives you some ideas.

Best regards,
   -Steve W
    http://imaptools.com/

On 1/11/2011 3:15 PM, Wim Vanbelle wrote:
> Well, the problem is that the requests are not always served.
>
> During load testing, say about 10 concurrent requests I also load the
> map. But there are randomly tiles that are never loaded. I thought this
> would be related to the defunct processes, but that is not a certainty.
>
> My setup is lighttpd + fastcgi.
> To be honest I'm in a pretty bad situation now, considering we go live
> with this in 9 days.
>
> Not sure what else I can do honestly.
>
>
> On 11 January 2011 19:05, Stephen Woodbridge <woodbri at swoodbridge.com
> <mailto:woodbri at swoodbridge.com>> wrote:
>
>     Here is an explanation of defunct processes:
>
>     http://www.webmasterworld.com/forum40/1032.htm
>
>     I'm sure there are others. So since you are running fastcgi, it is
>     the responsibility of the fastcgi parent process to clean up dead
>     child processes. It is likely that it is busy because you are doing
>     load testing or there is some subtle issue that is occurring. If you
>     are getting good responses from mapserver, you probably do not need
>     to worry about it unless you are getting tons of them.
>
>     If you are using apache, I believe there is a parameter that you can
>     set for fastcgi processes which will let them die after N requests.
>     This should clean those up and apache will spawn a new process if
>     needed to replace the that died.
>
>     -Steve W
>
>
>     On 1/11/2011 10:04 AM, Wim Vanbelle wrote:
>
>         Hi all,
>
>         I'm getting a lot of
>
>         27098 x  20   0     0    0    0 Z    1  0.0   0:00.03 mapserv
>         <defunct>
>         27104 x  20   0     0    0    0 Z    1  0.0   0:00.03 mapserv
>         <defunct>
>
>         while load testing mapserver. Is there any way I can go about
>         checking
>         out why this is happening? Especially when doing concurrency
>         tests it
>         seems to go sideways.
>
>         Currently i'm using :
>
>         MapServer version 5.6.5 OUTPUT=GIF OUTPUT=PNG OUTPUT=JPEG
>         OUTPUT=WBMP
>         OUTPUT=SWF OUTPUT=SVG SUPPORTS=PROJ SUPPORTS=AGG SUPPORTS=FREETYPE
>         SUPPORTS=ICONV SUPPORTS=FRIBIDI SUPPORTS=WMS_SERVER
>         SUPPORTS=WMS_CLIENT
>         SUPPORTS=WFS_SERVER SUPPORTS=WFS_CLIENT SUPPORTS=WCS_SERVER
>         SUPPORTS=SOS_SERVER SUPPORTS=FASTCGI SUPPORTS=THREADS SUPPORTS=GEOS
>         SUPPORTS=RGBA_PNG INPUT=EPPL7 INPUT=POSTGIS INPUT=OGR INPUT=GDAL
>         INPUT=SHAPEFILE
>
>         using FastCGI/Lighty.
>
>         Do note that the mapfile itself seems to be fine, since it does
>         render
>         content when i'm the single user using it.
>
>         Thanks for your expert insight :D.
>
>
>
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