Mapscript ,Mono, Apache and Linux : a great story

Wed Jun 21 14:18:41 PDT 2006

My configuration is the following

Mono (1.1.13) 
gtk 2.8
Apache (2.2.?) with de mod_mono compiled for it mod_mono 1.1.14
MApscript (4.8.3). 
Postgres 8.1.3 and Postgis 1.1.1
Geos 2.2.1
GDAL 1.3.1
Ming 0.30
Proj4 (4.4.9)
Libiconv 1.9.1
gd-2.0.33

All these programs has been compiler on the computer

Mapserver has been compiled with the configure : 
./configure --with-gdal=/usr/local/bin/gdal-config
--with-ogr=/usr/local/bin/gdal-config
--with-postgis=/usr/local/pgsql/bin/pg_config --with-ming --with-png
--with-jpeg --with-zlib --with-tiff --with-geos=/usr/local/bin/geos-config
--with-gif --with-proj --with-gd=/usr/local --with-httpd=/usr/sbin/httpd2

At The question : 1. The problem is manifested with the mono runtime using
linux/apache with mod_mono : YES

At The question : 2. The problem is systematic and occurs every time when
calling pLayerParcelle.getFeature in localiser_parcelle on a postgis layer
(after excluding the code i have mentioned) : 

I did not include your code at this time because (if i understood your last
email, the modification was about the dynamic creation of LayerObjet object.
My last answer was about this. I wrote that i disabled the function to make
a test and i prodcued the same error with the getfeature
Do you want that i make the test? 
Most of the error are on the getfeature function but not all.

At The question : How did you use your application to get this problem out?
I get the problem when i'm connecting to the web site with my browser

At The question : Would it be possible to make a simple test application
that produces the same behaviour?
I can make an mono console application that create mapserver output file and
test the result

regards

-----------------------------------------
Xavier Mauclaire
-------------------------------------------------------

-----Message d'origine-----
De : Tamas Szekeres [mailto:szekerest at gmail.com] 
Envoyé : mercredi 21 juin 2006 22:24
À : 'Xavier Mauclaire'
Cc : MAPSERVER-USERS at lists.umn.edu
Objet : RE: [UMN_MAPSERVER-USERS] Mapscript ,Mono, Apache and Linux : a
great story

Xavier,

I would assure you i am keen to look for a fix for your issue. This problem
was reported for java as well. I was dealing with mostly by reviewing your
code so far, but it seems i shall have to set up a proper evironment to
reproduce this problem. Unfortunately i didn't have enough time to realize
it. Please confirm me about the followings i know about this issue is true:

1. The problem is manifested with the mono runtime using linux/apache with
mod_mono 2. The problem is systematic and occurs every time when calling
pLayerParcelle.getFeature in localiser_parcelle on a postgis layer (after
excluding the code i have mentioned)

How did you use your application to get this problem out?
Would it be possible to make a simple test application that produces the
same behaviour?

It would be useful make a conversation about it on the mapserver IRC for
example. 

Thanks,

Tamas

-----Original Message-----
From: Xavier Mauclaire [mailto:xavier.mauclaire at geoter.fr]
Sent: Wednesday, June 21, 2006 9:31 PM
To: 'Tamas Szekeres'
Cc: MAPSERVER-USERS at lists.umn.edu
Subject: RE: [UMN_MAPSERVER-USERS] Mapscript ,Mono, Apache and Linux : a
great story

Tamas
Do you think i may install an older version of mapserver, the 4.8.0 or other
one ?
I'm very annoyed
regards

-----------------------------------------
Xavier Mauclaire
-------------------------------------------------------

-----Message d'origine-----
De : Tamas Szekeres [mailto:szekerest at gmail.com] Envoyé : vendredi 16 juin
2006 15:57 À : Xavier Mauclaire Cc : MAPSERVER-USERS at lists.umn.edu Objet :
Re: [UMN_MAPSERVER-USERS] Mapscript ,Mono, Apache and Linux : a great story

Xavier,

> All the layerObj object i use  in my program are déclared in the 
> mapfile so i don't need to create layerObj from scratch using the
constructor.
> When you say that if a layerObj reference with a previously released 
> native memory segment, it may causing the error, what are the 
> consequences for my code ? Using the Dispose method is there the 
> solution to avoid this problem ?

Most of the mapscript classes implement the IDisposable interface since they
maintain unmanaged memory segments. It is a good practice to explicitly call
Dispose (or by the using directive) if a newly created object is not needed
any more. However you might want to maintain the mapObj reference for a
longer period and the disposing will occur during the program destruction.
Getting an existing object reference (eg. as returned by
GetLayerByName) does not create a new object, so calling dispose is not
needed.
All of the objects internally maintain a flag indicating if it should free
the internal memory during the finalization. So calling Dispose in the
previous case might also not cause any problems.

So you may not have to take care much of these issues the existing problems
may dedicated to unproper handling of this reference and considered to be
fixed. However it is not so easy to locate the reason of the problem since
the crash will be slipped out on a subsequent finalization or the program
termination.

>
> How can i get CVS code ?

http://mapserver.gis.umn.edu/development/cvs/

using Tortoise CVS is fairly straightforward.

> Why this code works well under windows and scratches under linux ?

You may use different frameworks and CRT libraries. The problem may still
exists but not manifested.

Tamas

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