Call From s150/192.168.109.150 to 0.0.0.0:10020 failed on connection exception:

参考博客：点击打开链接

Hadoop连接本地数据库的时候报错

Exception in thread "main" java.io.IOException: java.net.ConnectException: 
Call From s150/192.168.109.150 to 0.0.0.0:10020 failed on connection exception: 
java.net.ConnectException: Connection refused; For more details see: 
 http://wiki.apache.org/hadoop/ConnectionRefused

原因：historyservice没有启动

配置yarn-site.xml，添加历史服务器

然后在sbin目录下执行命令

 mr-jobhistory-daemon.sh start historyserver

就可以了，不需要重启