Error: Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster

最新推荐文章于 2022-12-20 20:09:32 发布

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文章标签：

#hadoop #mapreduce #hdfs #大数据

在尝试在Hadoop 3.1.3集群上运行wordcount程序时遇到错误：找不到或加载主类org.apache.hadoop.mapreduce.v2.app.MRAppMaster。解决方法是在mapred-site.xml和yarn-site.xml配置文件中添加Hadoop应用的类路径设置，确保包含所有必要的Hadoop组件路径。

Hadoop3.1.3在集群上运行自带wordcount功能，抱如下错误信息

[2021-03-23 10:00:56.464]Container exited with a non-zero exit code 1. Error file: prelaunch.err.
Last 4096 bytes of prelaunch.err :
Last 4096 bytes of stderr :
Error: Could not find or load main class org.apache.hadoop.mapreduce.v2.app.MRAppMaster

解决办法

在mapred-site.xml中的configuration标签里添加如下信息

<property>
                  <name>mapreduce.application.classpath</name>             
                  <value>                                                  
                        /opt/module/hadoop-3.1.3/etc/hadoop,               
                        /opt/module/hadoop-3.1.3/share/hadoop/common/*,    
                        /opt/module/hadoop-3.1.3/share/hadoop/common/lib/*,
        /opt/module/hadoop-3.1.3/share/hadoop/hdfs/*,                      
      /opt/module/hadoop-3.1.3/share/hadoop/hdfs/lib/*,                    
      /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/*,                   
      /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/lib/*,               
      /opt/module/hadoop-3.1.3/share/hadoop/yarn/*,                        
      /opt/module/hadoop-3.1.3/share/hadoop/common/lib/*,                  
      /opt/module/hadoop-3.1.3/share/hadoop/hdfs/*,                        
      /opt/module/hadoop-3.1.3/share/hadoop/hdfs/lib/*,                    
      /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/*,                   
      /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/lib/*,               
      /opt/module/hadoop-3.1.3/share/hadoop/yarn/*,                        
      /opt/module/hadoop-3.1.3/share/hadoop/yarn/lib/*                     
                </value>                                                   
        </property>

在yarn-site.xml中添加如下信息

<property>                                                         
    <name>yarn.application.classpath</name>                                
    <value>                                                                
        /opt/module/hadoop-3.1.3/etc/hadoop,                               
        /opt/module/hadoop-3.1.3/share/hadoop/common/*,                    
        /opt/module/hadoop-3.1.3/share/hadoop/common/lib/*,                
        /opt/module/hadoop-3.1.3/share/hadoop/hdfs/*,                      
        /opt/module/hadoop-3.1.3/share/hadoop/hdfs/lib/*,                  
        /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/*,                 
        /opt/module/hadoop-3.1.3/share/hadoop/mapreduce/lib/*,             
        /opt/module/hadoop-3.1.3/share/hadoop/yarn/*,                      
        /opt/module/hadoop-3.1.3/share/hadoop/yarn/lib/*                   
    </value>                                                               
  </property>

注意前面填写自己的Hadoop安装目录