Error: Could not find or load main class org.apache.hadoop.mapred.YarnChild

错误原因：mapred-site.xml配置错误

错误详情：

<property>
    <name>mapreduce.map.env</name>
    <value>HADOOP_MAPRED_HOME=/urs/local/hadoop</value>
  </property>

订正后：

<property>
    <name>mapreduce.map.env</name>
    <value>HADOOP_MAPRED_HOME=/usr/local/hadoop</value>
  </property>