君知君不知

**问题1 ：**安装spark-yarn前确定yarn能否正常调度，以下为测试用例hadoop jar $HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.2.jar wordcount /input /output其中 /input目录先创建完并在其内加入wordcount的文件，如touch 1.txtecho >>1.txt a a bb b b cc c将/input文件上传到hdfs的根目录

Caused by: io.netty.channel.AbstractChannelAnnotatedNoRouteToHostException:没有到主机的路由:/10.47.55.99:45538atsun.nio.ch.SocketChannelImpl.checkConnect(NativeMethod)atsun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)atio.netty.channel.socket