[Mapserver-dev] MS concurrency problem with vector symbols

[woodbri at swoodbridge.com]

Mark,

Mapserver, and therefore Mapscript, are not yet thread-safe. The 
developers have been making a lot of changes to the source to remedy 
this, and I don't think it is totally fixed in ms-3.7/4.0, let along 
3.6.5.

You can search the archives for "thread safe" to get more info. By 
the way, this is also the same reason that PHP must be built as a CGI 
in Apache and not as a module if you want to use PHP/mapscript.

-Steve W.

On 4 Jun 2003 at 15:41, Mark Cave-Ayland wrote:

> Hi everyone,
> 
> Since submitting a patch to the mapserver-users mailing list (see
> http://mapserver.gis.umn.edu/data2/wilma/mapserver-users/0305/msg00581
> .h tml) that allows use of Perl Mapscript under mod_perl, I think I
> may have found some kind of concurrency problem in MS 3.6.5.
> 
> What I am finding is that initially running Perl Mapscript under
> mod_perl to return an image containing several point layers to the
> browser works fine until the browser is refreshed several times in
> quick succession. Then what happens is that the layers that are being
> drawn using vector symbols disappear and don't come back until Apache
> is restarted. If these layers are changed so that they use a PNG
> symbol instead then the problem doesn't occur. Running the same script
> as CGI causes all layers to always render correctly.
> 
> So what I'm thinking is that there is some sort of concurrency issue
> in libmap to do with drawing vector symbols. Has anyone had any
> experience of this already and is it a problem with Mapserver or could
> it be the GD library (I am currently using 1.8.4)? Or has this already
> been identified and fixed in the upcoming 3.7/4.0 release?
> 
> 
> Many thanks,
> 
> Mark.
> 
> ---
> 
> Mark Cave-Ayland
> Webbased Ltd.
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> Derriford
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> England
> 
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