[mapserver] Java VM Crashes using the Mapscript API

[Christian Schroeder]

Hello Benedikt!

Thank you very much for this tip,
now the segfault does not seem to occour any more and our problem seems 
to be solved with that.

Thank you very much for your help!

Best Regards,
Christian


Benedikt Rothe schrieb:

>
> 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.
> > >>
> > > > [...]
> > >