Hi Richard,
nice to see you on the list.
Unfortunately it is not possible to replace ClassFactoryClassPool without
patching as this class is not a service. This class is just instantiated in
few places inside the internal API.
You could file a JIRA issue and live with your patch in the meanwhile. We
hope to replace Javassist by ASM in 5.3, so probably all the problems we
have with Javassist will just disappear.
Regards
On Sat, Jan 22, 2011 at 6:07 PM, Richard Schurig <richard.schu...@me.com>wrote:
> hi all,
>
> we're using Tapestry IOC in an OSGi environment (Equinox 3.4) and recently
> discovered some serious class loading issues when installing multiple
> versions of the Tapestry Jars (5.1.0.5 and 5.2.4).
>
> the problem itself lies in the class ClassFactoryClassPool, which picks up
> every class loader from every class it ever sees. this completely bypasses
> the OSGi way of class loading!
>
> let me give an example: imagine 2 OSGi bundles names A and B as well as 2
> Tapestry IOC bundles named T5.1 and T5.2. A is using imports from T5.1 and B
> is using imports from T5.2. but A is also using imports from B. an every day
> scenario in OSGi. now what happens: the IOC registry starting in bundle A is
> manipulating some class in its bundle, which has references to a class in B.
> this results in ClassFactoryClassPool picking up the class loader of the
> B-class (the bundle class loader of bundle B) and therefore seeing also all
> T5.2 classes. so you end up with two Tap versions in allLoaders, and it's
> just a matter of timing, if you have a working sequence in the chain.
>
> the solution seems to be just using the thread context class loader, which
> (correctly set) provides all the classes needed by IOC. i did not understand
> the purpose the picking up class loaders anyway, is that a fix for
> tomcat/jetty? i tested the solution by patching (naahh) Tap IOC 5.1.0.5
> ClassFactoryClassPool like that:
>
> public ClassFactoryClassPool(ClassLoader contextClassLoader)
> {
> super(null);
>
> ClassPath path = new LoaderClassPath(contextClassLoader);
> insertClassPath(path);
> }
>
> public synchronized void addClassLoaderIfNeeded(ClassLoader loader)
> {
> // Just do nothing
> }
>
> This worked for me: in the first place a lot of "ClassNotFoundExceptions"
> occurred, revealing all the classes that we're accessible by bypassing the
> OSGi Bundle Class Loader, but after adding them to the imports of my bundle,
> everything was fine.
>
> So now the question: is there a way to suppress this "picking up class
> loader" mechanism? maybe somehow replacing the ClassFactoryClassPool with a
> custom implementation without patching?
>
> thanks in advance
>
>
>
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--
Best regards,
Igor Drobiazko
http://tapestry5.de
