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https://issues.apache.org/jira/browse/FELIX-2653?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Richard S. Hall reassigned FELIX-2653:
--------------------------------------
Assignee: Richard S. Hall
> LinkageError caused by duplicate class definition during implicit boot
> delegation
> ---------------------------------------------------------------------------------
>
> Key: FELIX-2653
> URL: https://issues.apache.org/jira/browse/FELIX-2653
> Project: Felix
> Issue Type: Bug
> Components: Framework
> Affects Versions: framework-3.0.4
> Environment: java version "1.6.0_21"
> Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
> Java HotSpot(TM) Server VM (build 17.0-b16, mixed mode)
> Reporter: Sahoo
> Assignee: Richard S. Hall
> Priority: Critical
> Fix For: framework-3.2.0
>
>
> I am seeing linkage errors caused by attempt to load duplicate classes and I
> think it is caused by implicit boot delegation. In our server log, we see the
> following exception stack:
> java.lang.LinkageError: loader (instance of java/net/URLClassLoader):
> attempted duplicate class definition for name: "com/acme/Foo"
> at java.lang.ClassLoader.defineClass1(Native Method)
> at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
> at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
> at
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
> at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
> at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
> at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
> at java.security.AccessController.doPrivileged(Native Method)
> at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
> at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> at com.acme.Foo$Factory.createRequest(Foo.java:93)
> I tried to trace the execution to find out what causes the class to be
> defined for the first time and with the help of btrace
> (http://projectkenai.com/projects/btrace/), I could obtain the stack and
> relevant information. First time the class is defined, the stack looks like
> this:
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
> java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
> java.net.URLClassLoader.access$000(URLClassLoader.java:58)
> java.net.URLClassLoader$1.run(URLClassLoader.java:197)
> java.security.AccessController.doPrivileged(Native Method)
> java.net.URLClassLoader.findClass(URLClassLoader.java:190)
> java.lang.ClassLoader.loadClass(ClassLoader.java:307)
> java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> org.apache.felix.framework.ModuleImpl.getEnclosingClass(ModuleImpl.java:1570)
> org.apache.felix.framework.ModuleImpl.isClassNotLoadedFromBundle(ModuleImpl.java:1545)
> org.apache.felix.framework.ModuleImpl.doImplicitBootDelegation(ModuleImpl.java:1498)
> org.apache.felix.framework.ModuleImpl.searchDynamicImports(ModuleImpl.java:1452)
> org.apache.felix.framework.ModuleImpl.findClassOrResourceByDelegation(ModuleImpl.java:727)
> org.apache.felix.framework.ModuleImpl.access$300(ModuleImpl.java:73)
> org.apache.felix.framework.ModuleImpl$ModuleClassLoader.loadClass(ModuleImpl.java:1733)
> java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> org.apache.felix.framework.ModuleImpl.getClassByDelegation(ModuleImpl.java:638)
> org.apache.felix.framework.Felix.loadBundleClass(Felix.java:1599)
> org.apache.felix.framework.BundleImpl.loadClass(BundleImpl.java:904)
> org.jvnet.hk2.osgiadapter.OSGiModuleImpl$3$1.run(OSGiModuleImpl.java:399)
> java.security.AccessController.doPrivileged(Native Method)
> org.jvnet.hk2.osgiadapter.OSGiModuleImpl$3.loadClass(OSGiModuleImpl.java:395)
> java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> com.sun.enterprise.v3.server.APIClassLoaderServiceImpl$APIClassLoader.loadClass(APIClassLoaderServiceImpl.java:169)
> java.lang.ClassLoader.loadClass(ClassLoader.java:296)
> java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> com.acme.Foo$Factory.bar(Foo.java:93)
> As you can see, when bar method is called, VM tries to load
> com.acme.Foo.class and the call reaches
> org.apache.felix.framework.ModuleImpl.getEnclosingClass. getEnclosingClass
> actually causes the enclosing class, com.acme.Foo, to be defined. So, VM
> actually records this new class in loaded classes cache of the appropriate
> loader, but Felix does not consult the loaded classes cache again before
> trying to define the class.
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