Error: Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster
自己搭建了一套伪分布的大数据环境,运行Hadoop包中自带的示例时,出现如下错误:
错误: 找不到或无法加载主类 org.apache.hadoop.mapreduce.v2.app.MRAppMaster
原因:
hadoop集群上运行build动作时提示以上错误,原因是yarn-site.xml和mapred-site.xml中的yarn.application.classpath没有进行配置。
解决方法:
找到yarn-site.xml和mapred-site.xml,并在configuration标签中,添加如下代码:
1 <property> 2 <name>yarn.application.classpath</name> 3 <value> 4 /bigdata/hadoop-3.0.3/etc/hadoop:/bigdata/hadoop-3.0.3/share/hadoop/common/lib/*:/bigdata/hadoop-3.0.3/share/hadoop/common/*:/bigdata/hadoop-3.0.3/share/hadoop/hdfs:/bigdata/hadoop-3.0.3/share/hadoop/hdfs/lib/*:/bigdata/hadoop-3.0.3/share/hadoop/hdfs/*:/bigdata/hadoop-3.0.3/share/hadoop/yarn/lib/*:/bigdata/hadoop-3.0.3/share/hadoop/yarn/*:/bigdata/hadoop-3.0.3/share/hadoop/mapreduce/lib/*:/bigdata/hadoop-3.0.3/share/hadoop/mapreduce/*:/bigdata/hadoop-3.0.3/contrib/capacity-scheduler/*.jar 5 </value> 6 </property>
注:我的$HADOOP_HOME=bigdata/hadoop-3.0.3
修改完了,记得format一下。