1, make

2, start servers:
   ./server 127.0.0.1 12345 &>/dev/null &
   ./server 127.0.0.1 12346 &>/dev/null &
   ./server 127.0.0.1 12347 &>/dev/null &

3, start client:
   ./client address_list.txt

4, remove one address from `address_list.txt'.

5, signal client to reload address list from `address_list.txt':
   killall -s SIGTERM client

6, add a new address into `address_list.txt'.

7, signal client to reload address list from `address_list.txt':
   killall -s SIGTERM client

8, test done, stop all servers:
   killall server