title: java.lang.ClassNotFoundException: org.apache.log4j.Level Exception
body: <p>I have met with the following exception and it's the first time I came across with this one:</p>
  
  <pre><code>Caused by: java.lang.NoClassDefFoundError: org/apache/log4j/Level
      at org.apache.hadoop.mapred.JobConf.&lt;clinit&gt;(JobConf.java:357) ~[hadoop-mapreduce-client-core-2.7.1.jar:na]
      at java.lang.Class.forName0(Native Method) ~[na:1.8.0_91]
      at java.lang.Class.forName(Class.java:348) ~[na:1.8.0_91]
      at org.apache.hadoop.conf.Configuration.getClassByNameOrNull(Configuration.java:2134) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.util.ReflectionUtils.setJobConf(ReflectionUtils.java:95) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:78) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:136) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.Groups.&lt;init&gt;(Groups.java:79) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.Groups.&lt;init&gt;(Groups.java:74) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.Groups.getUserToGroupsMappingService(Groups.java:303) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.UserGroupInformation.initialize(UserGroupInformation.java:283) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.UserGroupInformation.ensureInitialized(UserGroupInformation.java:260) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.UserGroupInformation.loginUserFromSubject(UserGroupInformation.java:790) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.UserGroupInformation.getLoginUser(UserGroupInformation.java:760) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.security.UserGroupInformation.getCurrentUser(UserGroupInformation.java:633) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem$Cache$Key.&lt;init&gt;(FileSystem.java:2812) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem$Cache$Key.&lt;init&gt;(FileSystem.java:2802) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:2668) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:371) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:170) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:355) ~[hadoop-common-2.7.1.jar:na]
      at org.apache.hadoop.fs.Path.getFileSystem(Path.java:295) ~[hadoop-common-2.7.1.jar:na]
      at org.springframework.data.hadoop.store.support.OutputStoreObjectSupport.findInitFiles(OutputStoreObjectSupport.java:110) ~[spring-data-hadoop-store-2.3.0.RELEASE.jar:2.3.0.RELEASE]
      at org.springframework.data.hadoop.store.support.OutputStoreObjectSupport.initOutputContext(OutputStoreObjectSupport.java:93) ~[spring-data-hadoop-store-2.3.0.RELEASE.jar:2.3.0.RELEASE]
      at org.springframework.data.hadoop.store.support.OutputStoreObjectSupport.onInit(OutputStoreObjectSupport.java:83) ~[spring-data-hadoop-store-2.3.0.RELEASE.jar:2.3.0.RELEASE]
      at org.springframework.data.hadoop.store.support.LifecycleObjectSupport.afterPropertiesSet(LifecycleObjectSupport.java:67) ~[spring-data-hadoop-store-2.3.0.RELEASE.jar:2.3.0.RELEASE]
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
      at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574) ~[spring-beans-4.2.6.RELEASE.jar:4.2.6.RELEASE]
      ... 66 common frames omitted
  Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Level
      at java.net.URLClassLoader.findClass(URLClassLoader.java:381) ~[na:1.8.0_91]
      at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[na:1.8.0_91]
      at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) ~[na:1.8.0_91]
      at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[na:1.8.0_91]
      ... 94 common frames omitted
  </code></pre>
  
  <p>I have tried <a href="https://issues.apache.org/jira/browse/MRUNIT-219" rel="nofollow noreferrer">this</a>. But it doesn't solves the problem. Also looked at <a href="https://stackoverflow.com/questions/10585656/java-lang-classnotfoundexception-org-apache-log4j-level">here</a> and it too disappointed.</p>
  
  <p>Any help will be appreciated.</p>