Change list to set in supervisor for saving pids of dynamic temprary children

Since initial arguments of temporary children under simple_one_for_one
supervisors are not saved, only a list of pids was stored in such
supervisors. When adding/deleting many children, this would scale
badly. To avoid this the list is now changed to a set.

2 files changed, 68 insertions, 17 deletions

diff --git a/lib/stdlib/src/supervisor.erl b/lib/stdlib/src/supervisor.erl
index 4fd7f1d47c..09a01a9aea 100644
--- a/lib/stdlib/src/supervisor.erl
+++ b/lib/stdlib/src/supervisor.erl
@@ -65,11 +65,13 @@
 -type child() :: #child{}.
 
 -define(DICT, dict).
+-define(SETS, sets).
+-define(SET, set).
 
 -record(state, {name,
 		strategy               :: strategy(),
 		children = []          :: [child()],
-		dynamics               :: ?DICT() | list(),
+		dynamics               :: ?DICT() | ?SET(),
 		intensity              :: non_neg_integer(),
 		period                 :: pos_integer(),
 		restarts = [],
@@ -363,8 +365,8 @@ handle_call(which_children, _From, #state{children = [#child{restart_type = temp
 							     child_type = CT,
 							     modules = Mods}]} =
 		State) when ?is_simple(State) ->
-    Reply = lists:map(fun(Pid) -> {undefined, Pid, CT, Mods} end, dynamics_db(temporary,
-									      State#state.dynamics)),
+    Reply = lists:map(fun(Pid) -> {undefined, Pid, CT, Mods} end,
+                      ?SETS:to_list(dynamics_db(temporary, State#state.dynamics))),
     {reply, Reply, State};
 
 handle_call(which_children, _From, #state{children = [#child{restart_type = RType,
@@ -389,7 +391,7 @@ handle_call(count_children, _From, #state{children = [#child{restart_type = temp
 							     child_type = CT}]} = State)
   when ?is_simple(State) ->
     {Active, Count} =
-	lists:foldl(fun(Pid, {Alive, Tot}) ->
+	?SETS:fold(fun(Pid, {Alive, Tot}) ->
 			   if is_pid(Pid) -> {Alive+1, Tot +1};
 			      true -> {Alive, Tot + 1} end
 		   end, {0, 0}, dynamics_db(temporary, State#state.dynamics)),
@@ -800,24 +802,27 @@ save_child(Child, #state{children = Children} = State) ->
     State#state{children = [Child |Children]}.
 
 save_dynamic_child(temporary, Pid, _, #state{dynamics = Dynamics} = State) ->
-    State#state{dynamics = [Pid | dynamics_db(temporary, Dynamics)]};
+    State#state{dynamics = ?SETS:add_element(Pid, dynamics_db(temporary, Dynamics))};
 save_dynamic_child(RestartType, Pid, Args, #state{dynamics = Dynamics} = State) ->
     State#state{dynamics = ?DICT:store(Pid, Args, dynamics_db(RestartType, Dynamics))}.
 
 dynamics_db(temporary, undefined) ->
-    [];
+    ?SETS:new();
 dynamics_db(_, undefined) ->
     ?DICT:new();
 dynamics_db(_,Dynamics) ->
     Dynamics.
 
-dynamic_child_args(_, Dynamics) when is_list(Dynamics)->
-    {ok, undefined};
 dynamic_child_args(Pid, Dynamics) ->
-    ?DICT:find(Pid, Dynamics).
+    case ?SETS:is_set(Dynamics) of
+        true ->
+            {ok, undefined};
+        false ->
+            ?DICT:find(Pid, Dynamics)
+    end.
 
 state_del_child(#child{pid = Pid, restart_type = temporary}, State) when ?is_simple(State) ->
-    NDynamics = lists:delete(Pid, dynamics_db(temporary, State#state.dynamics)),
+    NDynamics = ?SETS:del_element(Pid, dynamics_db(temporary, State#state.dynamics)),
     State#state{dynamics = NDynamics};
 state_del_child(#child{pid = Pid, restart_type = RType}, State) when ?is_simple(State) ->
     NDynamics = ?DICT:erase(Pid, dynamics_db(RType, State#state.dynamics)),
@@ -871,10 +876,13 @@ get_dynamic_child(Pid, #state{children=[Child], dynamics=Dynamics}) ->
 	    end
     end.
 
-is_dynamic_pid(Pid, Dynamics) when is_list(Dynamics) ->
-    lists:member(Pid, Dynamics);
 is_dynamic_pid(Pid, Dynamics) ->
-    dict:is_key(Pid, Dynamics).
+    case ?SETS:is_set(Dynamics) of
+	true ->
+	    ?SETS:is_element(Pid, Dynamics);
+	false ->
+	    ?DICT:is_key(Pid, Dynamics)
+    end.
 
 replace_child(Child, State) ->
     Chs = do_replace_child(Child, State#state.children),
diff --git a/lib/stdlib/test/supervisor_SUITE.erl b/lib/stdlib/test/supervisor_SUITE.erl
index cc271bd047..c79a5002fb 100644
--- a/lib/stdlib/test/supervisor_SUITE.erl
+++ b/lib/stdlib/test/supervisor_SUITE.erl
@@ -28,8 +28,8 @@
 	 init_per_group/2,end_per_group/2, init_per_testcase/2,
 	 end_per_testcase/2]).
 
-%% Indirect spawn export
--export([init/1]).
+%% Internal export
+-export([init/1, terminate_all_children/1]).
 
 %% API tests
 -export([ sup_start_normal/1, sup_start_ignore_init/1, 
@@ -55,7 +55,8 @@
 %% Misc tests
 -export([child_unlink/1, tree/1, count_children_memory/1,
 	 do_not_save_start_parameters_for_temporary_children/1,
-	 do_not_save_child_specs_for_temporary_children/1]).
+	 do_not_save_child_specs_for_temporary_children/1,
+	 simple_one_for_one_scale_many_temporary_children/1]).
 
 %%-------------------------------------------------------------------------
 
@@ -72,7 +73,8 @@ all() ->
      {group, normal_termination},
      {group, abnormal_termination}, child_unlink, tree,
      count_children_memory, do_not_save_start_parameters_for_temporary_children,
-     do_not_save_child_specs_for_temporary_children].
+     do_not_save_child_specs_for_temporary_children,
+     simple_one_for_one_scale_many_temporary_children].
 
 groups() -> 
     [{sup_start, [],
@@ -1201,6 +1203,47 @@ restarted(Sup, {Id,_,_,_,_,_} = ChildSpec, TerminateHow) ->
     {error, {already_started, _}} = supervisor:start_child(Sup, ChildSpec).
 
 
+%%-------------------------------------------------------------------------
+%% OTP-9242: Pids for dynamic temporary children were saved as a list,
+%% which caused bad scaling when adding/deleting many processes.
+simple_one_for_one_scale_many_temporary_children(_Config) ->
+    process_flag(trap_exit, true),
+    Child = {child, {supervisor_1, start_child, []}, temporary, 1000,
+	     worker, []},
+    {ok, _SupPid} = start_link({ok, {{simple_one_for_one, 2, 3600}, [Child]}}),
+
+    C1 = [begin 
+		 {ok,P} = supervisor:start_child(sup_test,[]), 
+		 P
+	     end || _<- lists:seq(1,1000)],
+    {T1,done} = timer:tc(?MODULE,terminate_all_children,[C1]),
+    
+    C2 = [begin 
+		 {ok,P} = supervisor:start_child(sup_test,[]), 
+		 P
+	     end || _<- lists:seq(1,10000)],
+    {T2,done} = timer:tc(?MODULE,terminate_all_children,[C2]),
+    
+    Scaling = T2 div T1,
+    if Scaling > 20 ->
+	    %% The scaling shoul be linear (i.e.10, really), but we
+	    %% give some extra here to avoid failing the test
+	    %% unecessarily.
+	    ?t:fail({bad_scaling,Scaling});
+       true ->
+	    ok
+    end.
+    
+
+terminate_all_children([C|Cs]) ->
+    ok = supervisor:terminate_child(sup_test,C),
+    terminate_all_children(Cs);
+terminate_all_children([]) ->
+    done.
+
+
+
+%%-------------------------------------------------------------------------
 terminate(Pid, Reason) when Reason =/= supervisor ->
     terminate(dummy, Pid, dummy, Reason).