diff --git a/src/emqx_session.erl b/src/emqx_session.erl
index 9c28884c9..e9bc0ff98 100644
--- a/src/emqx_session.erl
+++ b/src/emqx_session.erl
@@ -417,7 +417,7 @@ handle_call({register_publish_packet_id, PacketId, Ts}, _From,
                       {{error, ?RC_PACKET_IDENTIFIER_IN_USE}, State};
                   false ->
                       State1 = State#state{awaiting_rel = maps:put(PacketId, Ts, AwaitingRel)},
-                      {ok, ensure_await_rel_timer(State1)}
+                      {ok, ensure_stats_timer(ensure_await_rel_timer(State1))}
               end;
           true ->
               ?LOG(warning, "Dropped qos2 packet ~w for too many awaiting_rel", [PacketId], State),
@@ -430,7 +430,7 @@ handle_call({pubrec, PacketId, _ReasonCode}, _From, State = #state{inflight = In
     reply(
       case emqx_inflight:contain(PacketId, Inflight) of
           true ->
-              {ok, acked(pubrec, PacketId, State)};
+              {ok, ensure_stats_timer(acked(pubrec, PacketId, State))};
           false ->
               ?LOG(warning, "The PUBREC PacketId ~w is not found.", [PacketId], State),
               emqx_metrics:trans(inc, 'packets/pubrec/missed'),
@@ -442,7 +442,7 @@ handle_call({pubrel, PacketId, _ReasonCode}, _From, State = #state{awaiting_rel
     reply(
       case maps:take(PacketId, AwaitingRel) of
           {_Ts, AwaitingRel1} ->
-              {ok, State#state{awaiting_rel = AwaitingRel1}};
+              {ok, ensure_stats_timer(State#state{awaiting_rel = AwaitingRel1})};
           error ->
               ?LOG(warning, "The PUBREL PacketId ~w is not found", [PacketId], State),
               emqx_metrics:trans(inc, 'packets/pubrel/missed'),
@@ -477,7 +477,7 @@ handle_cast({subscribe, FromPid, {PacketId, _Properties, TopicFilters}},
                                           end}
                     end, {[], Subscriptions}, TopicFilters),
     suback(FromPid, PacketId, ReasonCodes),
-    noreply(State#state{subscriptions = Subscriptions1});
+    noreply(ensure_stats_timer(State#state{subscriptions = Subscriptions1}));
 
 %% UNSUBSCRIBE:
 handle_cast({unsubscribe, From, {PacketId, _Properties, TopicFilters}},
@@ -494,14 +494,14 @@ handle_cast({unsubscribe, From, {PacketId, _Properties, TopicFilters}},
                             end
                     end, {[], Subscriptions}, TopicFilters),
     unsuback(From, PacketId, ReasonCodes),
-    noreply(State#state{subscriptions = Subscriptions1});
+    noreply(ensure_stats_timer(State#state{subscriptions = Subscriptions1}));
 
 %% PUBACK:
 handle_cast({puback, PacketId, _ReasonCode}, State = #state{inflight = Inflight}) ->
     noreply(
       case emqx_inflight:contain(PacketId, Inflight) of
           true ->
-              dequeue(acked(puback, PacketId, State));
+              ensure_stats_timer(dequeue(acked(puback, PacketId, State)));
           false ->
               ?LOG(warning, "The PUBACK PacketId ~w is not found", [PacketId], State),
               emqx_metrics:trans(inc, 'packets/puback/missed'),
@@ -513,7 +513,7 @@ handle_cast({pubcomp, PacketId, _ReasonCode}, State = #state{inflight = Inflight
     noreply(
       case emqx_inflight:contain(PacketId, Inflight) of
           true ->
-              dequeue(acked(pubcomp, PacketId, State));
+              ensure_stats_timer(dequeue(acked(pubcomp, PacketId, State)));
           false ->
               ?LOG(warning, "The PUBCOMP PacketId ~w is not found", [PacketId], State),
               emqx_metrics:trans(inc, 'packets/pubcomp/missed'),
@@ -565,7 +565,7 @@ handle_cast({resume, #{conn_pid        := ConnPid,
     emqx_hooks:run('session.resumed', [#{client_id => ClientId}, attrs(State)]),
 
     %% Replay delivery and Dequeue pending messages
-    noreply(dequeue(retry_delivery(true, State1)));
+    noreply(ensure_stats_timer(dequeue(retry_delivery(true, State1))));
 
 handle_cast({update_expiry_interval, Interval}, State) ->
     {noreply, State#state{expiry_interval = Interval}};
@@ -590,7 +590,7 @@ handle_info({dispatch, Topic, Msg = #message{}}, State) ->
             ok = emqx_shared_sub:nack_no_connection(Msg),
             {noreply, State};
         false ->
-            noreply(handle_dispatch(Topic, Msg, State))
+            noreply(ensure_stats_timer(handle_dispatch(Topic, Msg, State)))
     end;
 
 %% Do nothing if the client has been disconnected.
@@ -601,11 +601,11 @@ handle_info({timeout, Timer, retry_delivery}, State = #state{retry_timer = Timer
     noreply(retry_delivery(false, State#state{retry_timer = undefined}));
 
 handle_info({timeout, Timer, check_awaiting_rel}, State = #state{await_rel_timer = Timer}) ->
-    noreply(expire_awaiting_rel(State#state{await_rel_timer = undefined}));
+    State1 = State#state{await_rel_timer = undefined},
+    noreply(ensure_stats_timer(expire_awaiting_rel(State1)));
 
 handle_info({timeout, Timer, emit_stats},
-            State = #state{client_id = ClientId,
-                           stats_timer = Timer}) ->
+            State = #state{client_id = ClientId, stats_timer = Timer}) ->
     emqx_metrics:commit(),
     _ = emqx_sm:set_session_stats(ClientId, stats(State)),
     NewState = State#state{stats_timer = undefined},
@@ -931,8 +931,7 @@ dequeue(State = #state{inflight = Inflight}) ->
 
 dequeue2(State = #state{mqueue = Q}) ->
     case emqx_mqueue:out(Q) of
-        {empty, _Q} ->
-            State;
+        {empty, _Q} -> State;
         {{value, Msg}, Q1} ->
             %% Dequeue more
             dequeue(dispatch(Msg, State#state{mqueue = Q1}))
@@ -972,7 +971,8 @@ ensure_will_delay_timer(State = #state{will_msg = #message{headers = #{'Will-Del
 ensure_will_delay_timer(State) ->
     State.
 
-ensure_stats_timer(State = #state{enable_stats = true, stats_timer = undefined,
+ensure_stats_timer(State = #state{enable_stats = true,
+                                  stats_timer = undefined,
                                   idle_timeout = IdleTimeout}) ->
     State#state{stats_timer = emqx_misc:start_timer(IdleTimeout, emit_stats)};
 ensure_stats_timer(State) ->
@@ -1010,11 +1010,11 @@ reply({Reply, State}) ->
     reply(Reply, State).
 
 reply(Reply, State) ->
-    {reply, Reply, ensure_stats_timer(State)}.
+    {reply, Reply, State}.
 
 noreply(State) ->
-    {noreply, ensure_stats_timer(State)}.
+    {noreply, State}.
 
 shutdown(Reason, State) ->
-    {stop, {shutdown, Reason}, State}.
+    {stop, Reason, State}.