- hilo de ejecución de las tareas de MapReduce, no se puede encontrar la clase principal de plomo
[2019-12-31 20:02:59.464]Container exited with a non-zero exit code 1. Error file: prelaunch.err. Last 4096 bytes of prelaunch.err : Last 4096 bytes of stderr : 错误: 找不到或无法加载主类 org.apache.hadoop.mapreduce.v2.app.MRAppMaster
Solución: En la línea de comandos, escriba: ruta de clase hadoop
[admin@master hadoop]$ hadoop classpath
/opt/module/hadoop/etc/hadoop:/opt/module/hadoop/share/hadoop/common/lib/*:/opt/module/hadoop/share/hadoop/common/*:/opt/module/hadoop/share/hadoop/hdfs:/opt/module/hadoop/share/hadoop/hdfs/lib/*:/opt/module/hadoop/share/hadoop/hdfs/*:/opt/module/hadoop/share/hadoop/mapreduce/lib/*:/opt/module/hadoop/share/hadoop/mapreduce/*:/opt/module/hadoop/share/hadoop/yarn:/opt/module/hadoop/share/hadoop/yarn/lib/*:/opt/module/hadoop/share/hadoop/yarn/*
El valor añadido en el fichero de salida correspondiente a la yarn.application.classpath hilo site.xml siguiente atributos, por ejemplo:
<property>
<name>yarn.application.classpath</name>
<value>/opt/module/hadoop/etc/hadoop:/opt/module/hadoop/share/hadoop/common/lib/*:/opt/module/hadoop/share/hadoop/common/*:/opt/module/hadoop/share/hadoop/hdfs:/opt/module/hadoop/share/hadoop/hdfs/lib/*:/opt/module/hadoop/share/hadoop/hdfs/*:/opt/module/hadoop/share/hadoop/mapreduce/lib/*:/opt/module/hadoop/share/hadoop/mapreduce/*:/opt/module/hadoop/share/hadoop/yarn:/opt/module/hadoop/share/hadoop/yarn/lib/*:/opt/module/hadoop/share/hadoop/yarn/*</value>
</property>
hilo de reinicio, vuelva a ejecutar tareas de MapReduce.
yarn --daemon stop resourcemanager
yarn --daemon stop nodemanager
yarn --daemon start resourcemanager
yarn --daemon start nodemanager
