The JarFileClassLoader throws an IllegalArgumentException when defining package com.ibm.websphere.ras.annotation

[dazavala]

The JarFileClassLoader unexpectedly throws an IllegalStateException when a server thread attempts to define package com.ibm.websphere.ras.annotation:

Caused by: java.lang.IllegalArgumentException: Package com.ibm.websphere.ras.annotation already defined.
at java.lang.ClassLoader.definePackage(ClassLoader.java:1255)
at com.ibm.ws.kernel.internal.classloader.JarFileClassLoader.definePackage(JarFileClassLoader.java:210)
at com.ibm.ws.kernel.internal.classloader.JarFileClassLoader.findClass(JarFileClassLoader.java:159)
at com.ibm.ws.kernel.internal.classloader.BootstrapChildFirstJarClassloader.loadClass(BootstrapChildFirstJarClassloader.java:84)
at java.lang.ClassLoader.loadClass(ClassLoader.java:853)

The exception is thrown whenever multiple server threads compete to load a class in the same package using the JarFileClassLoader, where one thread defines the package before another, and another thread attempts to redefine the package. The IllegalStateException will appear as the causal exception of an error reported by the server. For example:

[2/15/20 5:07:34:256 GMT] 0000001a id=00000000 LogService-24-com.ibm.ws.zos.core                            E CWWKE0701E: bundle com.ibm.ws.zos.core:1.0.38.cl200320200214-0300 (24)[com.ibm.ws.zos.core.internal.CoreBundleActivator(19)] : The activate method has thrown an exception java.lang.ExceptionInInitializerError
at java.lang.J9VMInternals.ensureError(J9VMInternals.java:146)
at java.lang.J9VMInternals.recordInitializationFailure(J9VMInternals.java:135)
at com.ibm.ws.zos.jni.internal.NativeMethodManagerImpl.start(NativeMethodManagerImpl.java:90)
at com.ibm.ws.zos.core.internal.CoreBundleActivator.activate(CoreBundleActivator.java:127)
...
Caused by: java.lang.IllegalArgumentException: Package com.ibm.websphere.ras.annotation already defined.
...

Thus far the problem has been detected for package com.ibm.websphere.ras.annotation, but the problem is general and may occur for other packages internal to the server.