Re: libgcj failure: Duplicate class registration

[Hannes Wallnoefer <hannes at helma dot at>]

Tom Tromey wrote:

> > > > > > ">" == hannes wallnoefer <hannes@helma.at> writes:
> > > > > >            
> > > I'm getting the following error message when adding a java class to a
> > > dynamically linked Apache module:
> > > libgcj failure: Duplicate class registration: GcjTest
> > >      
>
> With the current gcj, a given compiled class can only be loaded once
> by the system class loader.  If you try to link in a class more than
> once, you get this failure.
>
> This choice was the result of a lot of discussion a few years ago, see
> the list archives for the details.  (I don't have a ready pointer to
> the thread, sorry.)
>
>  
>
> > > #19 0x401576ed in apr_dso_load () from /usr/lib/libapr-0.so.0
> > > #20 0x08066c5d in load_module ()
> > >      
> > >
> > > Any idea what might be wrong?
> > >      
>
> Offhand it is hard to say.  I've run into this problem by accidentally
> pulling in a second (different) copy of libgcj.so.  I worked around
> it by setting the system property
> gnu.gcj.runtime.VMClassLoader.library_control to `never'.
> This disables the automatic loading of .so files.
>
>  

I found that the problem is Apache is calling dlopen() twice for each 
shared module. This is done on purpose to let modules set up their logs 
files or whatever. So I guess the only solution is to put the Java 
classes in a separate library and load that manually from my module. 
Unless there is a way to "forget" about the classes loaded in the first 
dlopen() pass, but I somehow doubt this.

Hannes