question on class loading behavior on array classes

[Joseph D. Darcy]

ravenex wrote:
> Hi all,
>
> Not sure where to ask, not sure if it's a bug or not so I'm seeking 
> for advice here.
>
> According the the JVM spec, 2nd edition, 5.3.3 Creating Array Classes, 
> both the bootstrap class loader and user-defined class loaders can 
> load array classes, and the corresponding class loaders involved are 
> recorded as initiating class loaders.
>
> But starting from JDK 6, Sun's JDK by default doesn't allow array 
> syntax in ClassLoader.loadClass()/ClassLoader.findSystemClass(); array 
> classes couldn't be created by calling defineClass() anyway, so this 
> effectively bans user-defined class loaders to be initiating class 
> loaders for array classes. Calling Class.forName(className, 
> initialize, classLoader) won't record classLoader as an initiating 
> class loader for an array class either.
>
> Is this an intended behavior?
>
> I'm expecting a call to Class.forName() would mark the loader as an 
> initiating one, for all classes (including array classes). That way I 
> won't have to keep a cache of my own in my custom class loader to keep 
> track of what's been loaded already. I read Bug 6500212 
> (http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6500212) and know 
> that I shouldn't call ClassLoader.loadClass() with array syntax, so I 
> switched to Class.forName(). But then when my class loader is asked to 
> load the same array class again, it calls findLoadedClass() and gets a 
> null back. That's pretty bad because I don't won't to get down to 
> SystemDictionary::resolve_array_class_or_null() every time I load an 
> array class. That'll force me to use my own cache to record just about 
> the same info as what the VM already has, plus the array classes 
> loaded, which looks like a bad smell to me.

Hello.

As noted in bug 6500212, the ban on allowing array syntax (bug 4976356) 
was intentional.  As this class loading issue is not specific to OpenJDK 
6, I suggest inquiring on the core-libs-dev at openjdk.java.net alias.

Regards,

-Joe