Mapscript crashing Tomcat --> [Panic]

[Frank Warmerdam]

Rodrigo Del C. Andrade wrote:
>      Greetings. dear list.
>      We are experiencing some troubling difficulties developing an 
> application with mapscript on a Java web based environment with tomcat.
>    Here is the deal: while using the app (not nearly done, but 
> functional enough at this stage) when one tries to zoom (in or out) or 
> pan the map more than a few times, Tomcat often will go down screaming 
> and the JVM just gives up on life.
>    I know this is probably not the right or best place to ask about it, 
> but it seems to be caused by the interaction of mapscript and the GD 
> library.
>         Here is the JVM output short version (long version is attached 
> at the bottom):
...
>    Any ideas? Full JVM error log is at the bottom. I am ready to give in 
> more info if needed.
>    Thanks in advance;
...

> Stack: [0xb0203000,0xb0284000),  sp=0xb0279ed4,  free space=475k
> Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, 
> C=native code)
> C  [libgd.so.2+0x8182]
> C  [libgd.so.2+0x9a16]  gdImageLine+0x4a6
> C  [libmapscript.so+0xad355]
> C  [libmapscript.so+0xb310e]  msDrawLineSymbolGD+0xe7e
> C  [libmapscript.so+0xa75fb]  msDrawLineSymbol+0x8b
> C  [libmapscript.so+0xa9cb2]  msDrawShape+0x17e2
> C  [libmapscript.so+0xaa6d8]  msDrawVectorLayer+0x398
> C  [libmapscript.so+0xaa97a]  msDrawLayer+0xaa
> C  [libmapscript.so+0xaba67]  msDrawMap+0x6a7
> C  [libmapscript.so+0x552b5]  

Rodrigo,

I'd suggesting seeing if you can reproduce this without Java involved.  I
suspect there is some sort of memory error in msDrawLineSymbolGD() (possibly
the infamous antialiasing bug?).

Capture your map configuration into a map file, and run the map through
shp2img or mapserv with the appropriate layers turned on, and similar
view configuration *and* run it under "valgrind" to quickly highly
memory corruption as soon as it happens.

If you can reproduce it this way,then you have something you can file
as a bug report.

MapServer is not bug free, and it is important to be able to narrow
down bugs without too much extraneous stuff.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org