Re: [Joeq-devel] NullPointerException in monitorenter (Bug?)

[David A. R. <dtr...@um...>]

Sorry all- correction: the source file is Monitor.java; the method is  
monitorenter().

On Aug 15, 2008, at 4:42 PM, David Antonio Ramos wrote:

> Hi Everyone,
>
> I've spent the greater part of this week trying to run a graphical
> Java application inside Joeq (native mode) on Linux 2.6.9-67.0.1.ELsmp
> with Sun JDK 1.5.0_01.  My main problem is that System.loadLibrary is
> not working properly when attempting to load the awt library.  I fixed
> one bug already in
> joeq_native/joeq/ClassLib/sun14_linux/java/lang/System.java by
> implementing mapLibraryName correctly.
>
> The application gets as far as executing ClassLoader.loadLibrary0, and
> executes the statement "synchronized(loadedLibraryNames){" (JDK1.5's
> java/lang/ClassLoader.java:1714).  This triggers
> joeq.Runtime.Monitor.monitorenter(Object k), which crashes on a
> NullPointerException because k is null.  However, loadedLibraryNames
> is an initialized static field inside JDK's ClassLoader class.  So how
> can it be null?  I suspect that the problem has to do with the various
> overloaded versions of ClassLoader inside Joeq, but I have not been
> able to fix it.  Below is a copy of the exception backtrace.  Please
> note that the line number for Monitor.java is off because I've added
> debug statements to pinpoint the problem.
>
> Has anyone successfully loaded shared JNI libraries from inside native
> Joeq?  Also, is there a good way to debug native Joeq?  GDB won't do
> much unless there's a seg fault.
>
> Thanks in advance!
> -David
>
> java.lang.ExceptionInInitializerError
>         at java.lang.Throwable.fillInStackTrace(Throwable.java:57)
>         at java.lang.Throwable.<init>(Throwable.java:181)
>         at java.lang.Error.<init>(Error.java:37)
>         at java.lang.LinkageError.<init>(LinkageError.java:26)
>         at
> java 
> .lang 
> .ExceptionInInitializerError.<init>(ExceptionInInitializerError.java: 
> 61)
>         at joeq.Class.jq_Class.invokeclinit(jq_Class.java:2448)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2431)
>         at
> joeq 
> .Compiler 
> .Reference 
> .x86.x86ReferenceLinker.invokestatic(x86ReferenceLinker.java:183)
>         at java.awt.Component.<clinit>(Component.java:545)
>         at  
> joeq.Runtime.ReflectionImpl.invokestatic_V(ReflectionImpl.java:326)
>         at
> joeq 
> .Compiler 
> .Reference 
> .x86.x86ReferenceLinker.invokeinterface(x86ReferenceLinker.java:220)
>         at joeq.Runtime.Reflection.invokestatic_V(Reflection.java:100)
>         at joeq.Class.jq_Class.invokeclinit(jq_Class.java:2442)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2431)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2427)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2427)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2427)
>         at joeq.Class.jq_Class.cls_initialize(jq_Class.java:2427)
>         at joeq.Main.JoeqVM.boot(JoeqVM.java:216)
> Caused by: java.lang.NullPointerException
>         at java.lang.Throwable.fillInStackTrace(Throwable.java:57)
>         at java.lang.Throwable.<init>(Throwable.java:181)
>         at java.lang.Exception.<init>(Exception.java:29)
>         at java.lang.RuntimeException.<init>(RuntimeException.java:32)
>         at  
> java.lang.NullPointerException.<init>(NullPointerException.java:36)
>         at
> joeq.Runtime.ExceptionDeliverer.trap_handler(ExceptionDeliverer.java: 
> 50)
>         at joeq.Runtime.Monitor.monitorenter(Monitor.java:64)
>         at java.lang.ClassLoader.loadLibrary0(ClassLoader.java:1714)
>         at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1668)
>         at java.lang.Runtime.loadLibrary0(Runtime.java:822)
>         at java.lang.System.loadLibrary(System.java:49)
>         at
> sun.security.action.LoadLibraryAction.run(LoadLibraryAction.java:50)
>         at
> joeq 
> .Compiler 
> .Reference 
> .x86.x86ReferenceLinker.invokeinterface(x86ReferenceLinker.java:220)
>         at
> java.security.AccessController.doPrivileged(AccessController.java:16)
>         at  
> sun.awt.NativeLibLoader.loadLibraries(NativeLibLoader.java:38)
>         at sun.awt.DebugHelper.<clinit>(DebugHelper.java:29)
>         at  
> joeq.Runtime.ReflectionImpl.invokestatic_V(ReflectionImpl.java:326)
>         at
> joeq 
> .Compiler 
> .Reference 
> .x86.x86ReferenceLinker.invokeinterface(x86ReferenceLinker.java:220)
>         at joeq.Runtime.Reflection.invokestatic_V(Reflection.java:100)
>         at joeq.Class.jq_Class.invokeclinit(jq_Class.java:2442)
>         ... 13 more
>
>
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