Exception thrown by CGLIB converter duting initialization of XStream

Hi Mirron,

I am closing this as "Cannot Reproduce", since the problem does not seem to be XStream related in first place. Have a look at the stack trace, the ClassCastException is thrown somewhere deep down in the sources of CGLIB, XStream simply tries to call a method of a class available in CGLIB. However, it seems that you have some incompatible versions of CGLIB in the class path, this ClassCastException is a typical symptom. Please have a look at the libs Jetty is loading at startup and look into your own dependencies.

If you have further questions, please ask on the user's list.

• Jörg

Closed after no further comment has been given.

I'm having the exact same trouble.

it looks like its inside cglib but its related to something xstream is doing.

my stack trace follows:

jvm 1 | java.lang.ExceptionInInitializerError
jvm 1 | at com.thoughtworks.xstream.converters.reflection.CGLIBEnhancedConverter.canConvert(CGLIBEnhancedConverter.java:67)
jvm 1 | at com.thoughtworks.xstream.core.DefaultConverterLookup.lookupConverterForType(DefaultConverterLookup.java:60)
jvm 1 | at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:65)
jvm 1 | at com.thoughtworks.xstream.core.TreeUnmarshaller.convertAnother(TreeUnmarshaller.java:59)
jvm 1 | at com.thoughtworks.xstream.core.TreeUnmarshaller.start(TreeUnmarshaller.java:142)
jvm 1 | at com.thoughtworks.xstream.core.AbstractTreeMarshallingStrategy.unmarshal(AbstractTreeMarshallingStrategy.java:33)
jvm 1 | at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:931)
jvm 1 | at com.thoughtworks.xstream.XStream.unmarshal(XStream.java:917)
jvm 1 | at com.thoughtworks.xstream.XStream.fromXML(XStream.java:861)
jvm 1 | at com.emineollc.config.ConfigManager.read(ConfigManager.java:55)
jvm 1 | at com.emineollc.model.hibernate.PersistenceManager.getEntityManagerFactory(PersistenceManager.java:46)
jvm 1 | at com.emineollc.model.hibernate.PersistenceManager.getEntityManager(PersistenceManager.java:71)
jvm 1 | at com.emineollc.model.hibernate.PersistenceManager.executeLoader(PersistenceManager.java:148)
jvm 1 | at com.emineollc.model.hibernate.Loader.load(Loader.java:9)
jvm 1 | at com.emineollc.webadmin.wicket.WicketApplication.migrate(WicketApplication.java:83)
jvm 1 | at com.emineollc.webadmin.wicket.WicketApplication.init(WicketApplication.java:29)
jvm 1 | at org.apache.wicket.protocol.http.WicketFilter.init(WicketFilter.java:561)
jvm 1 | at org.mortbay.jetty.servlet.FilterHolder.doStart(FilterHolder.java:99)
jvm 1 | at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
jvm 1 | at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:594)
jvm 1 | at org.mortbay.jetty.servlet.Context.startContext(Context.java:139)
jvm 1 | at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1218)
jvm 1 | at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:500)
jvm 1 | at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:448)
jvm 1 | at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
jvm 1 | at org.mortbay.jetty.handler.HandlerWrapper.doStart(HandlerWrapper.java:117)
jvm 1 | at org.mortbay.jetty.Server.doStart(Server.java:220)
jvm 1 | at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
jvm 1 | at com.emineollc.webadmin.AdminServer.startupService(AdminServer.java:29)
jvm 1 | at com.emineollc.Launcher.start(Launcher.java:61)
jvm 1 | at org.tanukisoftware.wrapper.WrapperManager$12.run(WrapperManager.java:2788)
jvm 1 | Caused by: java.lang.ClassCastException: net.sf.cglib.proxy.Enhancer$EnhancerKey$$KeyFactoryByCGLIB$$7fb24d72 cannot be cast to net.sf.cglib.core.KeyFactory
jvm 1 | at net.sf.cglib.core.KeyFactory$Generator.create(KeyFactory.java:145)
jvm 1 | at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:117)
jvm 1 | at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:108)
jvm 1 | at net.sf.cglib.core.KeyFactory.create(KeyFactory.java:104)
jvm 1 | at net.sf.cglib.proxy.Enhancer.<clinit>(Enhancer.java:69)
jvm 1 | ... 31 more

I don't want to reopen this because I can sense there is some tension here, but I have encountered this again in a special instance that I think XStream should account for. In multithreaded scenarios with separate classloaders, this issue can occur where registering a converter a cross classloaders will cause this exact issue. It is not always a classpath issue because it is possible to load these remotely.

Generally speaking, it is a classloader issue that where a workaround can be found by correcting the classpath. It is a workaround because this is not a solution since it only works in one specific scenario. It does not correct the other scenarios. The overall problem is just hidden from the developer at that point though because the classloader issue still exists.

I am using xstream 1.2.2 and I have only been able to solve this by proxying xstream. I work on a maven project where the version is fixed, so I cannot simply upgrade. Is this classloader issue fixed in later versions of xstream? If it is, maybe I can use that point to convince an upgrade. Maintaining a proxy is pretty difficult.

@r351574nc3: Simply open a new issue that describes exactly the scenario where you're facing this problem. And it would really help if you use a recent XStream version.