[mapserver-users] Mapscript/Java/Servlet users: give this a whirl...

[Harald Wehr]

Hi CF,

I faced the same problems some times ago and never found a solution to 
this problem.

See these mails i wrote to this list.

http://mapserver.gis.umn.edu/wilma/mapserver-users/0203/msg00298.html
http://mapserver.gis.umn.edu/wilma/mapserver-users/0204/msg00137.html
http://mapserver.gis.umn.edu/wilma/mapserver-users/0203/msg00373.html

> I've been having this very unusual problem running servlets and 
> mapscript.  As far as I can tell, it's working great except under one 
> condition.  If a user submits a request to the servlet, then hits the 
> browser's refresh button before the his/her previous one is finished, it 
> *crashes* my servlet engine.  This only happens if I'm executing 
> imageObj.draw() somewhere in it *and* trying to print a response back to 
> the client.  If I don't do anything with my HTTPServletResponse object, 
> I can hit refresh as many times as I want as fast as I want with no 
> problems.  Anyway, without getting too deep into the issue, etc. I would 
> be grateful if someone else could try doing this.

It is really curios to find the responsible fault. Sometimes it worked 
several times, some times the sevlet container crashes.

> 
> Submit a request to your servlet that draws a map and saves out to an 
> image (one that takes at few seconds or more).
> Then hold your <CTRL> key down (to make sure it refreshes) and hit your 
> refresh button a few times fast while your first request is still pending.
> Sometimes it'll keep showing you the cached page after the servlet 
> engine has crashed.  So after that, try moving to another page being 
> served by your servlet engine, or change your url params or just somehow 
> check to make sure it actually *is* running.

It seems to be a threading issue. Look at one of the above postings.

> 
> I'd like to hear your results.
> 
> Here's my environment.....
> Linux 7.3
> Tomcat 4 (standalone)
> JDK 1.4 (J2SDK)
> --------------
> MapServer version 3.6.0 OUTPUT=PNG OUTPUT=JPEG OUTPUT=WBMP SUPPORTS=PROJ 
> SUPPORTS=TTF SUPPORTS=WMS_SERVER INPUT=TIFF INPUT=EPPL7 INPUT=JPEG 
> INPUT=POSTGIS INPUT=SHAPEFILE
> ---------------
> My data is all in PostGIS

I have nearly the same environment.

Harald