java.lang.ClassNotFoundException: net.spy.memcached.compat.log.SLF4JLogger

Question

I added to Java opts -Dnet.spy.log.LoggerImpl=net.spy.memcached.compat.log.SLF4JLogger to set spymemcached to use slf4j as the logger. But I am getting the following WARNING in tomcat6 logs and I am puzzled over the error

net.spy.memcached.compat.log.SLF4JLogger not found while initializing net.spy.compat.log.LoggerFactory java.lang.ClassNotFoundException: net.spy.memcached.compat.log.SLF4JLogger

How can it be possible that the class SLF4JLogger is not found. That it was initializing LoggerFactory implies that the net.spy package was available and more generally the spy memcache jar was available. So how could it fail to find the other class.

log4j: setFile ended log4j: Adding appender named [SecurityAuditAppender] to category [SecurityAuditLogger]. Warning:  net.spy.memcached.compat.log.SLF4JLogger not found while initializing net.spy.compat.log.LoggerFactory java.lang.ClassNotFoundException: net.spy.memcached.compat.log.SLF4JLogger
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1680)
        at org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1526)
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Class.java:191)
        at net.spy.memcached.compat.log.LoggerFactory.getConstructor(LoggerFactory.java:131)
        at net.spy.memcached.compat.log.LoggerFactory.getNewInstance(LoggerFactory.java:115)
        at net.spy.memcached.compat.log.LoggerFactory.internalGetLogger(LoggerFactory.java:98)
        at net.spy.memcached.compat.log.LoggerFactory.getLogger(LoggerFactory.java:87)
        at net.spy.memcached.compat.log.LoggerFactory.getLogger(LoggerFactory.java:73)
        at net.spy.memcached.compat.SpyThread.getLogger(SpyThread.java:60)
        at net.spy.memcached.MemcachedConnection.createConnections(MemcachedConnection.java:152)
        at net.spy.memcached.MemcachedConnection.<init>(MemcachedConnection.java:128)
        at net.spy.memcached.DefaultConnectionFactory.createConnection(DefaultConnectionFactory.java:176)
        at net.spy.memcached.MemcachedClient.<init>(MemcachedClient.java:193)
        at net.spy.memcached.spring.MemcachedClientFactoryBean.getObject(MemcachedClientFactoryBean.java:72)
        at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.doGetObjectFromFactoryBean(FactoryBeanRegistrySupport.java:142)
        at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.getObjectFromFactoryBean(FactoryBeanRegistrySupport.java:102)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getObjectForBeanInstance(AbstractBeanFactory.java:1442)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:248)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
        at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveReference(BeanDefinitionValueResolver.java:322)
        at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveValueIfNecessary(BeanDefinitionValueResolver.java:106)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1360)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1118)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:517)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
        at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:913)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:464)
        at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:385)
        at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:284)
        at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:111)
        at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4210)
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:4709)
        at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:799)
        at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:779)
        at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:583)
        at org.apache.catalina.startup.HostConfig.deployDescriptor(HostConfig.java:675)
        at org.apache.catalina.startup.HostConfig.deployDescriptors(HostConfig.java:601)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:502)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1317)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:324)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:142)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1065)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:822)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1057)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:463)
        at org.apache.catalina.core.StandardService.start(StandardService.java:525)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:754)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:595)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:606)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:289)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:414)

Hawaii

What is your question? – Quimby

@Quimby sorry accidentally submitted prematurely, edited it. – Hawaii

Answer 1

If the WebAppClassLoader is throwing a ClassNotFoundException, then that class is not in your web application. Get the latest version of the spymemcached client jar (2.12.1 at the time of this writing) and put it in the WEB-INF/lib directory of your web application. Remove any other spymemcached jars from that directory to avoid classloading conflicts.

net.spy.memcached.compat.log.SLF4JLogger was not introduced until version 2.9.0, so if you're using an older version of net.spy:spymemcached, that would explain why it could find LoggerFactory but not SLF4JLogger.

Heroic

So I discovered that there were in addition to version 2.12.1 also the version 2.8.12 being included in the jar. I updated the pom.xml for all the subprojects to use version 2.12.1 and verified using jar tf that the new jar contains only spymemcached version 2.12.1. However, I am still seeing this problem. Ideas? – Hawaii

Did you verify the existence of the net.spy.memcached.compat.log.SLF4JLogger class file within the spymemcached jar, and that the spymemcached jar file is at WEB-INF/lib within your war file and/or your exploded war file? – Heroic

Triple checked that that is true. I'm beginning to think there is something subtle about how classpath lookup is defined at the beginnning of Spring initialization or something. But I really have no idea. – Hawaii

Try looking at the files in the META-INF directory inside your war and see if there's anything there that specifies custom classloader modifications. Also see if any other old spymemcached jars exist elsewhere in your tomcat installation, and remove them if you find any. – Heroic

oh this is annoying I just noticed there are other war files in the development environment that I'm not dealing with that are causing the log messages. – Hawaii

Answer 2

You can check your dependency tree with Dependency Plugin

mvn dependency:tree -Dverbose -Dincludes=spymemcached

if you see any other version beside 2.12.1, check it's top reference and add the exclude tag into it's maven dependency element like:

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-beans</artifactId>
    <version>3.0.3.RELEASE</version>
    <exclusions>
      <exclusion>
             <groupId>net.spy</groupId>
             <artifactId>spymemcached</artifactId>
      </exclusion>
    </exclusions>
</dependency

Wirephoto