after reading the chukwa starting log , the chukwa will first read
the chukwa_agent_checkpoint file and the read the initial_adaptors file.
The chukwa_agent_checkpoint recorded the position of log transferring ,
and the adaptors of chukwa when chukwa stopped .
When i restart chukwa , the chukwa will read both files. Will the adaptor
in initial_adaptors cover the adaptor in chukwa_agent_checkpoint ? These
adaptors has the same name and the file , just different offset .