logstash debug 打印: [filewatch.tailmode.handlers.grow] read_to_eof: get chunk

架构：之前同事已经把所有服务器的iis log 抽取到了一台服务器，目录结构：项目/IP/u_ex18*.log ，logstash1 -redis- logstash2 -es -kibana，日志抽取到一段时间就在logstash1 上不断打印  [2018-09-05T16:36:07,617][DEBUG][filewatch.tailmode.handlers.grow] read_to_eof: get chunk
[2018-09-05T16:36:07,618][DEBUG][filewatch.tailmode.handlers.grow] read_to_eof: get chunk
[2018-09-05T16:36:07,618][DEBUG][filewatch.tailmode.handlers.grow] read_to_eof: get chunk
。。。。。。。。。。。。。
 
logstash2 没有任务数据接收了
重启logstash1，日志开始重新同步
请问这是什么问题，请帮忙解答，谢谢。 
logstash1 config 配置文件如下：
input {
     file {
path => ["D:/Logs/a.com/IIS_Log/192.*/W3SV*/u_ex1809*.log","D:/Logs/b.com/IIS_Log/10.*/W3SVC*/u_ex1809*.log","D:/Logs/c.com/IIS_Log/10.*/W3SVC*/u_ex1809*.log","D:/Logs/d.com/IIS_Log/10.*/W3SVC*/u_ex1809*.log"]
        codec=>plain{charset=>"ISO-8859-1"}
        type => "iis_log"
        start_position => "beginning"
     }
}
output {
    redis {
         host => "1.1.1.1"
port => 1111
         key => "logstash-redis"
         password => "aaaaa"
         data_type => "list"
    }
}