root how to send heartbeat to server by tcp connection along mesh

[Tiffany]

Hello,I have set a connection between an esp8266(as root ) and my server using tcp .And as you know,heartbeat message must be always sent to server to keep the tcp connection.Then I tried use
' espconn_set_opt(&user_tcp_conn1,0x04);espconn_regist_write_finish(&user_tcp_conn1, user_tcp_write_finish); 'It only send 8 times;And maybe watchdog?I have seen a document said that watchdog can not support Infinite loop,either.
So how to send heartbeat to server by tcp connection along mesh,like demo_server.py,server always send message even in mesh.how to realize Infinite loop---- tcp heart message work along with mesh network.
Thanks.Hope for your reply