Gaurav Saini Gaurav Saini - 7 months ago 34
Java Question

Unable to initialize log4j

I'm trying to initialize log4j-1.2.8 for my application by creating a listener class implemented from the ApplicationLifecycleListener of Weblogic 9.2. When I deploy the application, I'm getting following exceptions:

java.lang.NoClassDefFoundError: org/apache/log4j/spi/RepositorySelector
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at weblogic.utils.classloaders.GenericClassLoader.defineClass(GenericClassLoader.java:338)
at weblogic.utils.classloaders.GenericClassLoader.findLocalClass(GenericClassLoader.java:291)
at weblogic.utils.classloaders.GenericClassLoader.findClass(GenericClassLoader.java:259)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:158)
at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
at myApp.LoggerStartupService.preStart(LoggerStartupService.java:40)
at weblogic.application.internal.flow.BaseLifecycleFlow$PreStartAction.run(BaseLifecycleFlow.java:187)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
at weblogic.application.internal.flow.BaseLifecycleFlow$BaseAction.invoke(BaseLifecycleFlow.java:95)
at weblogic.application.internal.flow.BaseLifecycleFlow.preStart(BaseLifecycleFlow.java:53)
at weblogic.application.internal.flow.HeadLifecycleFlow.prepare(HeadLifecycleFlow.java:199)
at weblogic.application.internal.BaseDeployment$1.next(BaseDeployment.java:615)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
at weblogic.application.internal.BaseDeployment.prepare(BaseDeployment.java:191)
at weblogic.application.internal.DeploymentStateChecker.prepare(DeploymentStateChecker.java:147)
at weblogic.deploy.internal.targetserver.AppContainerInvoker.prepare(AppContainerInvoker.java:61)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.createAndPrepareContainer(ActivateOperation.java:189)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doPrepare(ActivateOperation.java:87)
at weblogic.deploy.internal.targetserver.operations.AbstractOperation.prepare(AbstractOperation.java:217)
at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentPrepare(DeploymentManager.java:718)
at weblogic.deploy.internal.targetserver.DeploymentManager.prepareDeploymentList(DeploymentManager.java:1185)
at weblogic.deploy.internal.targetserver.DeploymentManager.handlePrepare(DeploymentManager.java:247)
at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.prepare(DeploymentServiceDispatcher.java:157)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doPrepareCallback(DeploymentReceiverCallbackDeliverer.java:157)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.access$000(DeploymentReceiverCallbackDeliverer.java:12)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer$1.run(DeploymentReceiverCallbackDeliverer.java:45)
at weblogic.work.ServerWorkManagerImpl$WorkAdapterImpl.run(ServerWorkManagerImpl.java:518)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:209)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:181)


where
myApp.LoggerStartupService
is the class implemented from
ApplicationLifecycleListener
.

I checked the classpath in my scripts and its set properly for all dependencies required for log4j. Appenders & Categories are also there in the log4j.xml. Looks like I'm missing something. Any ideas on what the problem may be?

Answer
java.lang.NoClassDefFoundError: org/apache/log4j/spi/RepositorySelector

This means that the in the message mentioned class is missing in the classpath during runtime (while it was available during compiletime of the calling class in question, that's the difference with ClassNotFoundException).

As this is used by Log4j itself, it's thus missing in the Log4j JAR file. The RepositorySelector javadoc learns us that it's introduced in Log4j 1.2. This would mean that there's a collision with another and older-versioned Log4j JAR file in the classpath which got precedence in classloading. It's likely somewhere hidden in one of the default classpaths of Weblogic. I don't do Weblogic, but as hinted by others, you can also try to change the classloading order, if it's supported by Weblogic. Consult its documentation.