HDFS balancer process start failed owing to daemon pid file is not cleared in some exception senario

HDFS balancer process start failed owing to daemon pid file is not cleared in some exception senario, but there is no useful information in log to trouble shoot as below.

//代码占位符
hadoop_error "${daemonname} is running as process $(cat "${daemon_pidfile}")

but actually, the process is not running as the error msg details above.

Therefore, some more explicit information should be print in error log to guide  users to clear the pid file and where the pid file location is.