prep_stop to close listeners

apps/emqttd/src/emqttd_app.erl

@@ -31,7 +31,7 @@
 -behaviour(application).
 
 %% Application callbacks
--export([start/2, stop/1]).
+-export([start/2, prep_stop/1, stop/1]).
 
 -define(PRINT_MSG(Msg), io:format(Msg)).
 
@@ -128,10 +128,16 @@ worker_spec(Name, Opts) ->
         {Name, start_link, [Opts]},
             permanent, 10000, worker, [Name]}.
 
--spec stop(State :: term()) -> term().
-stop(_State) ->
+%% close all listeners first...
+prep_stop(State) ->
+    %%TODO: esockd app should be running...
     {ok, Listeners} = application:get_env(listeners),
     emqttd:close_listeners(Listeners),
-    emqttd:unload_all_plugins(),
+    timer:sleep(2),
+    State.
+
+-spec stop(State :: term()) -> term().
+stop(_State) ->
     ok.
 
+