[mapserver] Java VM Crashes using the Mapscript API

[Benedikt Rothe]

the java-stacktrace shows, that the "delete" is called by from the 
"finalize"-method, i.e. from the 
garbage-collector. 
our experience is, that calling delete directly from the java-servlet is 
*much* safer. 

if we dynamically create mapserver-objects, we allway use code like this:
   classObj cO = new classObj(...); 
   .. 
   // Do something with cO 
   .. 
   //now cO isn't used any more 
   cO.delete() 

same rule for layers etc. 

Benedikt 
  
  

UMN MapServer Users List <MAPSERVER-USERS at LISTS.UMN.EDU> schrieb am 
21.06.2005 17:21:39:

> I'm forwarding this to the users list. Hopefully, Umberto will be able 
> to provide some insight.
> 
> cheers,
> Sean
> 
> On Jun 16, 2005, at 5:08 PM, Christian Schröder wrote:
> 
> > Dear Mr. Gillies,
> >
> > some weeks ago me and Florian Pepping contacted you because we had 
> > problems using the Java Mapscript API. Thanks to you we could solve 
> > these problems :-)
> >
> > Now we got our program doing what it's supposed to do but there is 
> > still a big problem left which we were not able to solve yet:
> > We created a simple servlet which is created inside a Tomcat 5.0 
> > Webserver. This servlet created a map image (png/jpg) and displays 
> > some specified objects on the map. (We use it for location based 
> > services --> "show me the position of the next printer").
> > After an irregular number of calls of our servlet which uses the Java 
> > Mapscript API the complete Java VM and with it the Tomcat crashes. I 
> > attached the error report below. The program works properly for a 
> > number of calls (between 5 and 1000 :-) ) and after that it crashes.
> > We have tried several versions of the mapserver (4.4.1, 4.4.2, 4.2.4, 
> > 4.6.1 RC1) and compiled the Java Mapscript Module with JDK 1.4.2 and 
> > 1.5.0. We also configured mapserver using the --with-threads option, 
> > but all this did not help. By the way the mapserv cgi-module works 
> > properly.
> >
> > Do you have an idea for this?
> >
> > Thanks for your anxiety
> >
> > Christian & Florian
> > University of Paderborn, Germany
> >
> >
> > -------------------------------------------------------------------
> >
> > JavaMapscriptLoader: mapscript native library has been loaded.
> >  * mapscript native library loaded *
> >
> > An unexpected exception has been detected in native code outside the 
> > VM.
> > Unexpected Signal : 11 occurred at PC=0x3338268
> > Function=delete_classObj+0x8
> > Library=/usr/lib/libmapscript.so
> >
> > Current Java thread:
> >         at edu.umn.gis.mapscript.mapscriptJNI.delete_classObj(Native 
> > Method)
> >         at edu.umn.gis.mapscript.classObj.delete(classObj.java:32)
> >         at edu.umn.gis.mapscript.classObj.finalize(classObj.java:26)
> >         at java.lang.ref.Finalizer.invokeFinalizeMethod(Native Method)
> >         at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:83)
> >         at java.lang.ref.Finalizer.access$100(Finalizer.java:14)
> >         at 
> > java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:160)
> >
> > Dynamic libraries:
> > Can not get information for pid = 10558
> >
> > Heap at VM Abort:
> > Heap
> >  def new generation   total 1152K, used 135K [0x08ae0000, 0x08c20000,
> > 0x08fc0000)
> >   eden space 1024K,   0% used [0x08ae0000, 0x08ae4078, 0x08be0000)
> >   from space 128K, 100% used [0x08c00000, 0x08c20000, 0x08c20000)
> >   to   space 128K,   0% used [0x08be0000, 0x08be0000, 0x08c00000)
> >  tenured generation   total 15048K, used 13624K [0x08fc0000, 
> > 0x09e72000,
> > 0x0cae0000)
> >    the space 15048K,  90% used [0x08fc0000, 0x09d0e1c0, 0x09d0e200,
> > 0x09e72000)
> >  compacting perm gen  total 18432K, used 18373K [0x0cae0000, 
> > 0x0dce0000,
> > 0x10ae0000)
> >    the space 18432K,  99% used [0x0cae0000, 0x0dcd1618, 0x0dcd1800,
> > 0x0dce0000)
> >
> > Local Time = Tue Jun 14 15:32:19 2005
> > Elapsed Time = 246
> > #
> > # The exception above was detected in native code outside the VM
> > #
> > # Java VM: Java HotSpot(TM) Client VM (1.4.2_08-b03 mixed mode)
> > #
> > # An error report file has been saved as /tmp/hs_err_pid10558.log.
> > # Please refer to the file for further information.
> > #
> >
> > -------------------------------------------------------------------
> >
> > On Mar 22, 2005, at 12:02 PM, Florian Pepping wrote:
> >
> >> Dear Mr. Gillies,
> >>
> >> I?m a student of the University of Paderborn in Germany and member of 

> >>  the project group ?Location Based Services for Wireless Devices?. In 

> >>  this project we try to position laptops and other WLAN-enabled 
> >> devices  using the signal strength of the WLAN. According to their 
> >> position, we  want to offer location based services to the persons 
> >> using the devices  (where I am; where?s the next printer; is there a 
> >> friend nearby)
> >>
> >> In order to do this, we want to use your mapserver and the Java 
> >> Mapscript API to generate maps according to the actual position and 
> >> situation. We like to customize the map of our building and add 
> >> points, lines and so on.
> >>
> >> We have been able to compile the whole mapserver and the Java 
> >> Mapscript API. A small Java example also works, which presents an 
> >> unchanged map of our building.
> >>
> > > [...]
> >
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