diff --git a/src/emqx_pool.erl b/src/emqx_pool.erl
index 8d927ddd9..276352797 100644
--- a/src/emqx_pool.erl
+++ b/src/emqx_pool.erl
@@ -23,16 +23,14 @@
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
          code_change/3]).
 
--record(state, {pool, id}).
-
 -define(POOL, ?MODULE).
 
 %% @doc Start pooler supervisor.
 start_link() ->
     emqx_pool_sup:start_link(?POOL, random, {?MODULE, start_link, []}).
 
-%% @doc Start pool
--spec(start_link(atom(), pos_integer()) -> {ok, pid()} | ignore | {error, term()}).
+%% @doc Start pool.
+-spec(start_link(atom(), pos_integer()) -> emqx_types:startlink_ret()).
 start_link(Pool, Id) ->
     gen_server:start_link({local, emqx_misc:proc_name(?MODULE, Id)}, ?MODULE, [Pool, Id], []).
 
@@ -49,13 +47,13 @@ async_submit(Fun) ->
 worker() ->
     gproc_pool:pick_worker(pool).
 
-%%-----------------------------------------------------------------------------
+%%------------------------------------------------------------------------------
 %% gen_server callbacks
-%%-----------------------------------------------------------------------------
+%%------------------------------------------------------------------------------
 
 init([Pool, Id]) ->
     true = gproc_pool:connect_worker(Pool, {Pool, Id}),
-    {ok, #state{pool = Pool, id = Id}}.
+    {ok, #{pool => Pool, id => Id}}.
 
 handle_call({submit, Fun}, _From, State) ->
     {reply, catch run(Fun), State};
@@ -79,15 +77,15 @@ handle_info(Info, State) ->
     emqx_logger:error("[Pool] unexpected info: ~p", [Info]),
     {noreply, State}.
 
-terminate(_Reason, #state{pool = Pool, id = Id}) ->
+terminate(_Reason, #{pool := Pool, id := Id}) ->
     true = gproc_pool:disconnect_worker(Pool, {Pool, Id}).
 
 code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
-%%-----------------------------------------------------------------------------
+%%------------------------------------------------------------------------------
 %% Internal functions
-%%-----------------------------------------------------------------------------
+%%------------------------------------------------------------------------------
 
 run({M, F, A}) ->
     erlang:apply(M, F, A);
diff --git a/src/emqx_pool_sup.erl b/src/emqx_pool_sup.erl
index b71c15f1e..b371549c0 100644
--- a/src/emqx_pool_sup.erl
+++ b/src/emqx_pool_sup.erl
@@ -26,8 +26,12 @@ spec(Args) ->
 
 -spec(spec(any(), list()) -> supervisor:child_spec()).
 spec(ChildId, Args) ->
-    {ChildId, {?MODULE, start_link, Args},
-     transient, infinity, supervisor, [?MODULE]}.
+    #{id       => ChildId,
+      start    => {?MODULE, start_link, Args},
+      restart  => transient,
+      shutdown => infinity,
+      type     => supervisor,
+      modules  => [?MODULE]}.
 
 -spec(start_link(atom() | tuple(), atom(), mfa()) -> {ok, pid()} | {error, term()}).
 start_link(Pool, Type, MFA) ->
diff --git a/src/emqx_zone.erl b/src/emqx_zone.erl
index 209f0323c..dd183dbdf 100644
--- a/src/emqx_zone.erl
+++ b/src/emqx_zone.erl
@@ -21,17 +21,20 @@
 -export([start_link/0]).
 -export([get_env/2, get_env/3]).
 -export([set_env/3]).
+-export([force_reload/0]).
+%% for test
+-export([stop/0]).
 
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
          code_change/3]).
 
--record(state, {timer}).
-
 -define(TAB, ?MODULE).
+-define(SERVER, ?MODULE).
 
+-spec(start_link() -> emqx_types:startlink_ret()).
 start_link() ->
-    gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
+    gen_server:start_link({local, ?SERVER}, ?MODULE, [], []).
 
 -spec(get_env(emqx_types:zone() | undefined, atom()) -> undefined | term()).
 get_env(undefined, Key) ->
@@ -50,7 +53,15 @@ get_env(Zone, Key, Def) ->
 
 -spec(set_env(emqx_types:zone(), atom(), term()) -> ok).
 set_env(Zone, Key, Val) ->
-    gen_server:cast(?MODULE, {set_env, Zone, Key, Val}).
+    gen_server:cast(?SERVER, {set_env, Zone, Key, Val}).
+
+-spec(force_reload() -> ok).
+force_reload() ->
+    gen_server:call(?SERVER, force_reload).
+
+-spec(stop() -> ok).
+stop() ->
+    gen_server:stop(?SERVER, normal, infinity).
 
 %%------------------------------------------------------------------------------
 %% gen_server callbacks
@@ -58,7 +69,11 @@ set_env(Zone, Key, Val) ->
 
 init([]) ->
     _ = emqx_tables:new(?TAB, [set, {read_concurrency, true}]),
-    {ok, element(2, handle_info(reload, #state{}))}.
+    {ok, element(2, handle_info(reload, #{timer => undefined}))}.
+
+handle_call(force_reload, _From, State) ->
+    _ = do_reload(),
+    {reply, ok, State};
 
 handle_call(Req, _From, State) ->
     emqx_logger:error("[Zone] unexpected call: ~p", [Req]),
@@ -73,11 +88,8 @@ handle_cast(Msg, State) ->
     {noreply, State}.
 
 handle_info(reload, State) ->
-    lists:foreach(
-      fun({Zone, Opts}) ->
-          [ets:insert(?TAB, {{Zone, Key}, Val}) || {Key, Val} <- Opts]
-      end, emqx_config:get_env(zones, [])),
-    {noreply, ensure_reload_timer(State), hibernate};
+    _ = do_reload(),
+    {noreply, ensure_reload_timer(State#{timer := undefined}), hibernate};
 
 handle_info(Info, State) ->
     emqx_logger:error("[Zone] unexpected info: ~p", [Info]),
@@ -93,6 +105,12 @@ code_change(_OldVsn, State, _Extra) ->
 %% Internal functions
 %%------------------------------------------------------------------------------
 
-ensure_reload_timer(State) ->
-    State#state{timer = erlang:send_after(10000, self(), reload)}.
+do_reload() ->
+    [ets:insert(?TAB, [{{Zone, Key}, Val} || {Key, Val} <- Opts])
+     || {Zone, Opts} <- emqx_config:get_env(zones, [])].
+
+ensure_reload_timer(State = #{timer := undefined}) ->
+    State#{timer := erlang:send_after(timer:minutes(5), self(), reload)};
+ensure_reload_timer(State) ->
+    State.
 
diff --git a/test/emqx_zone_SUITE.erl b/test/emqx_zone_SUITE.erl
index 282acc3e5..83c2ceaab 100644
--- a/test/emqx_zone_SUITE.erl
+++ b/test/emqx_zone_SUITE.erl
@@ -18,15 +18,21 @@
 -compile(nowarn_export_all).
 
 -include("emqx_mqtt.hrl").
+-include_lib("eunit/include/eunit.hrl").
 
 all() -> [t_set_get_env].
 
 t_set_get_env(_) ->
-    emqx_zone:start_link(),
-    ok = emqx_zone:set_env(china, language, chinese),
-    timer:sleep(100),   % make sure set_env/3 is okay
+    application:set_env(emqx, zones, [{china, [{language, chinese}]}]),
+    {ok, _} = emqx_zone:start_link(),
+    ct:print("~p~n", [ets:tab2list(emqx_zone)]),
     chinese = emqx_zone:get_env(china, language),
     cn470 = emqx_zone:get_env(china, ism_band, cn470),
     undefined = emqx_zone:get_env(undefined, delay),
-    500 = emqx_zone:get_env(undefined, delay, 500).
+    500 = emqx_zone:get_env(undefined, delay, 500),
+    application:set_env(emqx, zones, [{zone1, [{key, val}]}]),
+    ?assertEqual(undefined, emqx_zone:get_env(zone1, key)),
+    emqx_zone:force_reload(),
+    ?assertEqual(val, emqx_zone:get_env(zone1, key)),
+    emqx_zone:stop().