diff --git a/src/emqx_kernel_sup.erl b/src/emqx_kernel_sup.erl
index 40ec7cfd7..6289437ac 100644
--- a/src/emqx_kernel_sup.erl
+++ b/src/emqx_kernel_sup.erl
@@ -25,7 +25,7 @@ start_link() ->
 
 init([]) ->
     {ok, {{one_for_one, 10, 100},
-          [child_spec(emqx_pool, supervisor),
+          [child_spec(emqx_pool_sup, supervisor),
            child_spec(emqx_alarm_mgr, worker),
            child_spec(emqx_hooks, worker),
            child_spec(emqx_stats, worker),
@@ -41,6 +41,7 @@ child_spec(M, worker) ->
       shutdown => 5000,
       type     => worker,
       modules  => [M]};
+
 child_spec(M, supervisor) ->
     #{id       => M,
       start    => {M, start_link, []},
diff --git a/src/emqx_pool.erl b/src/emqx_pool.erl
index 7b12bea69..e90cdda6b 100644
--- a/src/emqx_pool.erl
+++ b/src/emqx_pool.erl
@@ -16,9 +16,14 @@
 
 -behaviour(gen_server).
 
--export([start_link/0, start_link/2]).
+-include("logger.hrl").
+
+-export([start_link/2]).
 -export([submit/1, submit/2]).
 -export([async_submit/1, async_submit/2]).
+-ifdef(TEST).
+-export([worker/0]).
+-endif.
 
 %% gen_server callbacks
 -export([init/1, handle_call/3, handle_cast/2, handle_info/2, terminate/2,
@@ -28,10 +33,6 @@
 
 -type(task() :: fun() | mfa() | {fun(), Args :: list(any())}).
 
-%% @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()) -> emqx_types:startlink_ret()).
 start_link(Pool, Id) ->
@@ -80,22 +81,22 @@ handle_call({submit, Task}, _From, State) ->
     {reply, catch run(Task), State};
 
 handle_call(Req, _From, State) ->
-    emqx_logger:error("[Pool] unexpected call: ~p", [Req]),
+    ?ERROR("[Pool] unexpected call: ~p", [Req]),
     {reply, ignored, State}.
 
 handle_cast({async_submit, Task}, State) ->
     try run(Task)
     catch _:Error:Stacktrace ->
-        emqx_logger:error("[Pool] error: ~p, ~p", [Error, Stacktrace])
+        ?ERROR("[Pool] error: ~p, ~p", [Error, Stacktrace])
     end,
     {noreply, State};
 
 handle_cast(Msg, State) ->
-    emqx_logger:error("[Pool] unexpected cast: ~p", [Msg]),
+    ?ERROR("[Pool] unexpected cast: ~p", [Msg]),
     {noreply, State}.
 
 handle_info(Info, State) ->
-    emqx_logger:error("[Pool] unexpected info: ~p", [Info]),
+    ?ERROR("[Pool] unexpected info: ~p", [Info]),
     {noreply, State}.
 
 terminate(_Reason, #{pool := Pool, id := Id}) ->
diff --git a/src/emqx_pool_sup.erl b/src/emqx_pool_sup.erl
index eb81233f9..58a6a08cd 100644
--- a/src/emqx_pool_sup.erl
+++ b/src/emqx_pool_sup.erl
@@ -16,10 +16,13 @@
 
 -behaviour(supervisor).
 
--export([spec/1, spec/2, start_link/3, start_link/4]).
+-export([spec/1, spec/2]).
+-export([start_link/0, start_link/3, start_link/4]).
 
 -export([init/1]).
 
+-define(POOL, emqx_pool).
+
 -spec(spec(list()) -> supervisor:child_spec()).
 spec(Args) ->
     spec(pool_sup, Args).
@@ -33,6 +36,10 @@ spec(ChildId, Args) ->
       type     => supervisor,
       modules  => [?MODULE]}.
 
+%% @doc Start the default pool supervisor.
+start_link() ->
+    start_link(?POOL, random, {?POOL, start_link, []}).
+
 -spec(start_link(atom() | tuple(), atom(), mfa()) -> {ok, pid()} | {error, term()}).
 start_link(Pool, Type, MFA) ->
     start_link(Pool, Type, emqx_vm:schedulers(), MFA).
diff --git a/test/emqx_pool_SUITE.erl b/test/emqx_pool_SUITE.erl
index 3d7d0f7e5..36ad7c507 100644
--- a/test/emqx_pool_SUITE.erl
+++ b/test/emqx_pool_SUITE.erl
@@ -15,22 +15,22 @@
 -module(emqx_pool_SUITE).
 
 -compile(export_all).
-
 -compile(nowarn_export_all).
 
 -include("emqx_mqtt.hrl").
-
 -include_lib("eunit/include/eunit.hrl").
 
-all() -> [
-          {group, submit_case},
-          {group, async_submit_case}
-         ].
+all() ->
+    [
+     {group, submit_case},
+     {group, async_submit_case},
+     t_unexpected
+    ].
 
 groups() ->
     [
      {submit_case, [sequence], [submit_mfa, submit_fa]},
-     {async_submit_case, [sequence], [async_submit_mfa]}
+     {async_submit_case, [sequence], [async_submit_mfa, async_submit_ex]}
     ].
 
 init_per_suite(Config) ->
@@ -40,26 +40,39 @@ init_per_suite(Config) ->
 end_per_suite(_Config) ->
     ok.
 
+init_per_testcase(_, Config) ->
+    {ok, Sup} = emqx_pool_sup:start_link(),
+    [{pool_sup, Sup}|Config].
+
+end_per_testcase(_, Config) ->
+    Sup = proplists:get_value(pool_sup, Config),
+    exit(Sup, normal).
+
 submit_mfa(_Config) ->
-    erlang:process_flag(trap_exit, true),
-    {ok, Pid} =  emqx_pool:start_link(),
     Result = emqx_pool:submit({?MODULE, test_mfa, []}),
-    ?assertEqual(15, Result),
-    gen_server:stop(Pid, normal, 3000),
-    ok.
+    ?assertEqual(15, Result).
 
 submit_fa(_Config) ->
-    {ok, Pid} =  emqx_pool:start_link(),
     Fun = fun(X) -> case X rem 2 of 0 -> {true, X div 2}; _ -> false end end,
     Result = emqx_pool:submit(Fun, [2]),
-    ?assertEqual({true, 1}, Result),
-    exit(Pid, normal).
+    ?assertEqual({true, 1}, Result).
+
+async_submit_mfa(_Config) ->
+    emqx_pool:async_submit({?MODULE, test_mfa, []}),
+    emqx_pool:async_submit(fun ?MODULE:test_mfa/0, []).
+
+async_submit_ex(_) ->
+    emqx_pool:async_submit(fun error_fun/0).
+
+t_unexpected(_) ->
+    Pid = emqx_pool:worker(),
+    ?assertEqual(ignored, gen_server:call(Pid, bad_request)),
+    ?assertEqual(ok, gen_server:cast(Pid, bad_msg)),
+    Pid ! bad_info,
+    ok = gen_server:stop(Pid).
 
 test_mfa() ->
     lists:foldl(fun(X, Sum) -> X + Sum end, 0, [1,2,3,4,5]).
 
-async_submit_mfa(_Config) ->
-    {ok, Pid} =  emqx_pool:start_link(),
-    emqx_pool:async_submit({?MODULE, test_mfa, []}),
-    exit(Pid, normal).
+error_fun() -> error(test_error).