我试图在eclipse中执行单词计数程序。
但是在执行程序时，我得到了以下错误
log4j:ERROR Could not instantiate class [org.apache.hadoop.log.metrics.EventCounter].
java.lang.ClassNotFoundException: org.apache.hadoop.log.metrics.EventCounter
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:190)
at org.apache.log4j.helpers.Loader.loadClass(Loader.java:198)
at org.apache.log4j.helpers.OptionConverter.instantiateByClassName(OptionConverter.java:327)
at org.apache.log4j.helpers.OptionConverter.instantiateByKey(OptionConverter.java:124)
at org.apache.log4j.PropertyConfigurator.parseAppender(PropertyConfigurator.java:785)
at org.apache.log4j.PropertyConfigurator.parseCategory(PropertyConfigurator.java:768)
at org.apache.log4j.PropertyConfigurator.configureRootCategory(PropertyConfigurator.java:648)
at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:514)
at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:580)
at org.apache.log4j.helpers.OptionConverter.selectAndConfigure(OptionConverter.java:526)
at org.apache.log4j.LogManager.<clinit>(LogManager.java:127)
at org.apache.log4j.Logger.getLogger(Logger.java:104)
at org.apache.commons.logging.impl.Log4JLogger.getLogger(Log4JLogger.java:289)
at org.apache.commons.logging.impl.Log4JLogger.<init>(Log4JLogger.java:109)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:526)
at org.apache.commons.logging.impl.LogFactoryImpl.createLogFromClass(LogFactoryImpl.java:1116)
at org.apache.commons.logging.impl.LogFactoryImpl.discoverLogImplementation(LogFactoryImpl.java:914)
at org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:604)
at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:336)
at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:310)
at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:685)
at org.apache.hadoop.conf.Configuration.<clinit>(Configuration.java:150)
at mapreducetest.main(mapreducetest.java:43)
log4j:ERROR Could not instantiate appender named "EventCounter".
13/09/02 11:17:18 INFO security.UserGroupInformation: JAAS Configuration already set up for Hadoop, not re-installing.
13/09/02 11:17:18 INFO jvm.JvmMetrics: Initializing JVM Metrics with processName=JobTracker, sessionId=
13/09/02 11:17:18 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
13/09/02 11:17:18 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
13/09/02 11:17:18 WARN mapred.JobClient: No job jar file set. User classes may not be found. See JobConf(Class) or JobConf#setJar(String).
13/09/02 11:17:18 INFO mapred.JobClient: Cleaning up the staging area file:/tmp/hadoop-hduser/mapred/staging/hduser201346744/.staging/job_local201346744_0001
Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/thirdparty/guava/common/collect/LinkedListMultimap
at org.apache.hadoop.hdfs.SocketCache.<init>(SocketCache.java:48)
at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:240)
at org.apache.hadoop.hdfs.DFSClient.<init>(DFSClient.java:208)
at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:89)
at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1563)
at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:67)
at org.apache.hadoop.fs.FileSystem$Cache.getInternal(FileSystem.java:1597)
at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1579)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:228)
at org.apache.hadoop.fs.Path.getFileSystem(Path.java:183)
at org.apache.hadoop.mapred.FileOutputFormat.checkOutputSpecs(FileOutputFormat.java:106)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:986)
at org.apache.hadoop.mapred.JobClient$2.run(JobClient.java:945)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:415)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1157)
at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:945)
at org.apache.hadoop.mapred.JobClient.submitJob(JobClient.java:919)
at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1368)
at mapreducetest.main(mapreducetest.java:59)
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.thirdparty.guava.common.collect.LinkedListMultimap
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 20 more
java.lang.ClassNotFoundException: org.apache.hadoop.log.metrics.EventCounter
类路径中缺少一个类。确保所有Apache Hadoop都在类路径中。有问题的罐子是hadoop-core-XXXXX.jar。
当您在终端中键入hadoop version时，您会得到什么版本的Hadoop？确保您拥有相同的hadoop-core.jar*以及eclipse类路径中Hadooplib目录中包含的所有库。
将所有jar文件添加到eclipse项目
1.）HADOOP_HOME目录下2.）在HADOOP_HOME/lib目录下
试着看看它是否有效。
然而，如果您在Windows下使用eclipse运行MR程序，您可能会进一步面临一些问题。