diff --git a/test/emqx_cm_SUITE.erl b/test/emqx_cm_SUITE.erl
index eb2c3564f..3f6950b3b 100644
--- a/test/emqx_cm_SUITE.erl
+++ b/test/emqx_cm_SUITE.erl
@@ -109,9 +109,13 @@ t_open_session(_) ->
     emqx_cm:unregister_channel(<<"clientid">>),
     ok = meck:unload(emqx_connection).
 
+rand_client_id() ->
+    list_to_binary("client-id-" ++ integer_to_list(erlang:system_time())).
+
 t_open_session_race_condition(_) ->
+    ClientId = rand_client_id(),
     ClientInfo = #{zone => external,
-                   clientid => <<"clientid">>,
+                   clientid => ClientId,
                    username => <<"username">>,
                    peerhost => {127,0,0,1}},
     ConnInfo = #{socktype => tcp,
@@ -136,11 +140,12 @@ t_open_session_race_condition(_) ->
                              exit(Reason)
                      end
                    end,
+    N = 1000,
     [spawn(
       fun() ->
               spawn(OpenASession),
               spawn(OpenASession)
-      end) || _ <- lists:seq(1, 1000)],
+      end) || _ <- lists:seq(1, N)],
 
     WaitingRecv = fun _Wr(N1, N2, 0) ->
                           {N1, N2};
@@ -151,45 +156,49 @@ t_open_session_race_condition(_) ->
                           end
                   end,
 
-    ct:pal("Race condition status: ~p~n", [WaitingRecv(0, 0, 2000)]),
+    {Succeeded, Failed} = WaitingRecv(0, 0, 2 * N),
+    ct:pal("Race condition status: succeeded=~p failed=~p~n", [Succeeded, Failed]),
 
-    ?assertEqual(1, ets:info(emqx_channel, size)),
-    ?assertEqual(1, ets:info(emqx_channel_conn, size)),
-    ?assertEqual(1, ets:info(emqx_channel_registry, size)),
+    ?assertMatch([_], ets:lookup(emqx_channel, ClientId)),
+    [Pid] = emqx_cm:lookup_channels(ClientId),
+    ?assertMatch([_], ets:lookup(emqx_channel_conn, {ClientId, Pid})),
+    ?assertMatch([_], ets:lookup(emqx_channel_registry, ClientId)),
 
-    [Pid] = emqx_cm:lookup_channels(<<"clientid">>),
-    exit(Pid, kill), timer:sleep(100),
-    ?assertEqual([], emqx_cm:lookup_channels(<<"clientid">>)).
+    exit(Pid, kill),
+    timer:sleep(100), %% TODO deterministic
+    ?assertEqual([], emqx_cm:lookup_channels(ClientId)).
 
 t_discard_session(_) ->
+    ClientId = rand_client_id(),
     #{conninfo := ConnInfo} = ?ChanInfo,
-    ok = emqx_cm:register_channel(<<"clientid">>, self(), ConnInfo),
+    ok = emqx_cm:register_channel(ClientId, self(), ConnInfo),
 
     ok = meck:new(emqx_connection, [passthrough, no_history]),
     ok = meck:expect(emqx_connection, call, fun(_, _) -> ok end),
     ok = meck:expect(emqx_connection, call, fun(_, _, _) -> ok end),
-    ok = emqx_cm:discard_session(<<"clientid">>),
-    ok = emqx_cm:register_channel(<<"clientid">>, self(), ConnInfo),
-    ok = emqx_cm:discard_session(<<"clientid">>),
-    ok = emqx_cm:unregister_channel(<<"clientid">>),
-    ok = emqx_cm:register_channel(<<"clientid">>, self(), ConnInfo),
-    ok = emqx_cm:discard_session(<<"clientid">>),
+    ok = emqx_cm:discard_session(ClientId),
+    ok = emqx_cm:register_channel(ClientId, self(), ConnInfo),
+    ok = emqx_cm:discard_session(ClientId),
+    ok = emqx_cm:unregister_channel(ClientId),
+    ok = emqx_cm:register_channel(ClientId, self(), ConnInfo),
+    ok = emqx_cm:discard_session(ClientId),
     ok = meck:expect(emqx_connection, call, fun(_, _) -> error(testing) end),
     ok = meck:expect(emqx_connection, call, fun(_, _, _) -> error(testing) end),
-    ok = emqx_cm:discard_session(<<"clientid">>),
-    ok = emqx_cm:unregister_channel(<<"clientid">>),
+    ok = emqx_cm:discard_session(ClientId),
+    ok = emqx_cm:unregister_channel(ClientId),
     ok = meck:unload(emqx_connection).
 
 t_discard_session_race(_) ->
+    ClientId = rand_client_id(),
     ?check_trace(
        begin
          #{conninfo := ConnInfo0} = ?ChanInfo,
          ConnInfo = ConnInfo0#{conn_mod := emqx_ws_connection},
          {Pid, Ref} = spawn_monitor(fun() -> receive stop -> exit(normal) end end),
-         ok = emqx_cm:register_channel(<<"clientid">>, Pid, ConnInfo),
+         ok = emqx_cm:register_channel(ClientId, Pid, ConnInfo),
          Pid ! stop,
          receive {'DOWN', Ref, process, Pid, normal} -> ok end,
-         ok = emqx_cm:discard_session(<<"clientid">>),
+         ok = emqx_cm:discard_session(ClientId),
          {ok, _} = ?block_until(#{?snk_kind := "session_already_gone", pid := Pid}, 1000)
        end,
        fun(_, _) ->
@@ -235,10 +244,10 @@ t_all_channels(_) ->
     ?assertEqual(true, is_list(emqx_cm:all_channels())).
 
 t_lock_clientid(_) ->
-    {true, _Nodes} = emqx_cm_locker:lock(<<"clientid">>),
-    {true, _Nodes} = emqx_cm_locker:lock(<<"clientid">>),
-    {true, _Nodes} = emqx_cm_locker:unlock(<<"clientid">>),
-    {true, _Nodes} = emqx_cm_locker:unlock(<<"clientid">>).
+    {true, Nodes} = emqx_cm_locker:lock(<<"clientid">>),
+    ?assertEqual({true, Nodes}, emqx_cm_locker:lock(<<"clientid">>)),
+    ?assertEqual({true, Nodes}, emqx_cm_locker:unlock(<<"clientid">>)),
+    ?assertEqual({true, Nodes}, emqx_cm_locker:unlock(<<"clientid">>)).
 
 t_message(_) ->
     ?CM ! testing,