[Mapserver-dev] MS concurrency problem with vector symbols

[Mark Cave-Ayland]

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.
Tamar Science Park
Derriford
Plymouth
PL6 8BX
England

Tel: +44 (0)1752 764445
Fax: +44 (0)1752 764446


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