opt supervisor shutdown问题

各位好！最近在学习otp,参考www.trapexit.org/Building_a_Non-blocking_TCP_server_using_OTP_principles写一个程序。
我在父进程用supervisor启动2个子进程，tcp_accept,tcp_client_sup,发现tcp_accept可以启动会有运行信息被打印出来，但是tcp_client_sup在执行时会shutdown。

启动进程代码如下:
server_sup

-module(server_sup).
-behaviour(supervisor).
-include ("./include/setting.hrl").
-export([start_link/1,test_start/0,init/1]).

%%Server supervisor

start_link(Args) ->
   ?DEBUG("server_sup start_link\r\n",[]),
   supervisor:start_link({local,?MODULE}, ?MODULE, Args).
   
test_start()->
	{ok, Pid} = supervisor:start_link({local,?MODULE}, ?MODULE, _Arg = []).
	%%unlink(Pid).
	
init([]) ->
	?DEBUG("server_sup init\r\n",[]),
	{ok, {{one_for_one, ?MAX_RESTART, ?MAX_TIME},
	  [
	  {tcp_accept, 
	    {tcp_accept, start_link, []},
	    permanent, 
	    ?SHUTDOWN_WAITING_TIME, 
	    worker, 
	    []},
	  {
	      tcp_client_sup,
	      {tcp_client_sup, start_link, [tcp_client_recv]},
	      permanent,
	      infinity,
	      supervisor,
	      []
    	}
	  ]}}.

tcp_client_sup代码:

-module(tcp_client_sup).
-behaviour(supervisor).
-include ("./include/setting.hrl").
-export([start_link/1,init/1,start_child/1]).

%%Client connection supervisor

start_link(Module) ->
   ?DEBUG("tcp_client_sup start_link ~s\r\n",[?MODULE]),
   supervisor:start_link({local,?MODULE}, ?MODULE, Module).

start_child([]) ->
   ?DEBUG("tcp_client_sup start_child\r\n",[]),
  supervisor:start_child(?MODULE, []).

init(Module) ->
  ?DEBUG("tcp_client_sup init\r\n",[]),
    {ok, {{simple_one_for_one, ?MAX_RESTART, ?MAX_TIME}, [{
    undefined,
    {tcp_client_recv, start_link, []},
    temporary,
    ?SHUTDOWN_WAITING_TIME,
    worker,
    []
  }]}}.

执行server_sup:test_start().
输出:
58> server_sup:test_start().
server_sup init
tcp_accept start_link
tcp_accept init
tcp_accept accept
tcp_client_sup start_child
** exception exit: shutdown

修改了下程序，一些小问题造成的，现在又向前进了一步，在start_child的部分shutdown。

封贴了，被一些零碎问题搞混乱了，已经解决了。