Added support of auto_hibernate_timeout option for gen_server, gen_fsm, gen_event process's.

There is realized gen_server, gen_fsm, gen_event automatic hibernation functionality.
Added unit tests for realized functionality.
Added documentation for auto_hibernate_timeout option.

4 files changed, 149 insertions, 117 deletions

diff --git a/lib/stdlib/src/gen.erl b/lib/stdlib/src/gen.erl
index 597830cf9a..90647f2cf4 100644
--- a/lib/stdlib/src/gen.erl
+++ b/lib/stdlib/src/gen.erl
@@ -26,7 +26,7 @@
 %%%
 %%% The standard behaviour should export init_it/6.
 %%%-----------------------------------------------------------------
--export([start/5, start/6, debug_options/2,
+-export([start/5, start/6, debug_options/2, auto_hibernate_timeout/1,
 	 name/1, unregister_name/1, get_proc_name/1, get_parent/0,
 	 call/3, call/4, reply/2, stop/1, stop/3]).
 
@@ -408,6 +408,14 @@ spawn_opts(Options) ->
 	    []
     end.
 
+auto_hibernate_timeout(Options) ->
+	case lists:keyfind(auto_hibernate_timeout, 1, Options) of
+		{_,AutoHibernateTimeout} ->
+			AutoHibernateTimeout;
+		false ->
+			infinity
+	end.
+
 debug_options(Name, Opts) ->
     case lists:keyfind(debug, 1, Opts) of
 	{_,Options} ->
diff --git a/lib/stdlib/src/gen_event.erl b/lib/stdlib/src/gen_event.erl
index 0c50b2aa08..7c15a40a4f 100644
--- a/lib/stdlib/src/gen_event.erl
+++ b/lib/stdlib/src/gen_event.erl
@@ -37,7 +37,7 @@
          stop/1, stop/3,
 	 notify/2, sync_notify/2,
 	 add_handler/3, add_sup_handler/3, delete_handler/3, swap_handler/3,
-	 swap_sup_handler/3, which_handlers/1, call/3, call/4, wake_hib/4]).
+	 swap_sup_handler/3, which_handlers/1, call/3, call/4, wake_hib/5]).
 
 -export([init_it/6,
 	 system_continue/3,
@@ -186,8 +186,9 @@ init_it(Starter, Parent, Name0, _, _, Options) ->
     process_flag(trap_exit, true),
     Name = gen:name(Name0),
     Debug = gen:debug_options(Name, Options),
+	AutoHibernateTimeout = gen:auto_hibernate_timeout(Options),
     proc_lib:init_ack(Starter, {ok, self()}),
-    loop(Parent, Name, [], Debug, false).
+    loop(Parent, Name, [], AutoHibernateTimeout, Debug, false).
 
 -spec add_handler(emgr_ref(), handler(), term()) -> term().
 add_handler(M, Handler, Args) -> rpc(M, {add_handler, Handler, Args}).
@@ -264,81 +265,83 @@ send(M, Cmd) ->
     M ! Cmd,
     ok.
 
-loop(Parent, ServerName, MSL, Debug, true) ->
-     proc_lib:hibernate(?MODULE, wake_hib, [Parent, ServerName, MSL, Debug]);
-loop(Parent, ServerName, MSL, Debug, _) ->
-    fetch_msg(Parent, ServerName, MSL, Debug, false).
+loop(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, true) ->
+     proc_lib:hibernate(?MODULE, wake_hib, [Parent, ServerName, MSL, AutoHibernateTimeout, Debug]);
+loop(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, _) ->
+    fetch_msg(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, false).
 
-wake_hib(Parent, ServerName, MSL, Debug) ->
-    fetch_msg(Parent, ServerName, MSL, Debug, true).
+wake_hib(Parent, ServerName, MSL, AutoHibernateTimeout, Debug) ->
+    fetch_msg(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, true).
 
-fetch_msg(Parent, ServerName, MSL, Debug, Hib) ->
+fetch_msg(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, Hib) ->
     receive
 	{system, From, Req} ->
 	    sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug,
-				  [ServerName, MSL, Hib],Hib);
+				  [ServerName, MSL, AutoHibernateTimeout, Hib],Hib);
 	{'EXIT', Parent, Reason} ->
 	    terminate_server(Reason, Parent, MSL, ServerName);
 	Msg when Debug =:= [] ->
-	    handle_msg(Msg, Parent, ServerName, MSL, []);
+	    handle_msg(Msg, Parent, ServerName, MSL, AutoHibernateTimeout, []);
 	Msg ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
 				      ServerName, {in, Msg}),
-	    handle_msg(Msg, Parent, ServerName, MSL, Debug1)
+	    handle_msg(Msg, Parent, ServerName, MSL, AutoHibernateTimeout, Debug1)
+    after AutoHibernateTimeout ->
+	    proc_lib:hibernate(?MODULE, wake_hib, [Parent, ServerName, MSL, AutoHibernateTimeout, Debug])
     end.
 
-handle_msg(Msg, Parent, ServerName, MSL, Debug) ->
+handle_msg(Msg, Parent, ServerName, MSL, AutoHibernateTimeout, Debug) ->
     case Msg of
 	{notify, Event} ->
 	    {Hib,MSL1} = server_notify(Event, handle_event, MSL, ServerName),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, {sync_notify, Event}} ->
 	    {Hib, MSL1} = server_notify(Event, handle_event, MSL, ServerName),
 	    reply(Tag, ok),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{'EXIT', From, Reason} ->
 	    MSL1 = handle_exit(From, Reason, MSL, ServerName),
-	    loop(Parent, ServerName, MSL1, Debug, false);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, false);
 	{_From, Tag, {call, Handler, Query}} ->
 	    {Hib, Reply, MSL1} = server_call(Handler, Query, MSL, ServerName),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, {add_handler, Handler, Args}} ->
 	    {Hib, Reply, MSL1} = server_add_handler(Handler, Args, MSL),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, {add_sup_handler, Handler, Args, SupP}} ->
 	    {Hib, Reply, MSL1} = server_add_sup_handler(Handler, Args, MSL, SupP),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, {delete_handler, Handler, Args}} ->
 	    {Reply, MSL1} = server_delete_handler(Handler, Args, MSL,
 						  ServerName),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, false);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, false);
 	{_From, Tag, {swap_handler, Handler1, Args1, Handler2, Args2}} ->
 	    {Hib, Reply, MSL1} = server_swap_handler(Handler1, Args1, Handler2,
 						     Args2, MSL, ServerName),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, {swap_sup_handler, Handler1, Args1, Handler2, Args2,
 		     Sup}} ->
 	    {Hib, Reply, MSL1} = server_swap_handler(Handler1, Args1, Handler2,
 						Args2, MSL, Sup, ServerName),
 	    reply(Tag, Reply),
-	    loop(Parent, ServerName, MSL1, Debug, Hib);
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib);
 	{_From, Tag, stop} ->
 	    catch terminate_server(normal, Parent, MSL, ServerName),
 	    reply(Tag, ok);
 	{_From, Tag, which_handlers} ->
 	    reply(Tag, the_handlers(MSL)),
-	    loop(Parent, ServerName, MSL, Debug, false);
+	    loop(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, false);
 	{_From, Tag, get_modules} ->
 	    reply(Tag, get_modules(MSL)),
-	    loop(Parent, ServerName, MSL, Debug, false);
+	    loop(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, false);
 	Other  ->
 	    {Hib, MSL1} = server_notify(Other, handle_info, MSL, ServerName),
-	    loop(Parent, ServerName, MSL1, Debug, Hib)
+	    loop(Parent, ServerName, MSL1, AutoHibernateTimeout, Debug, Hib)
     end.
 
 terminate_server(Reason, Parent, MSL, ServerName) ->
@@ -392,18 +395,18 @@ terminate_supervised(Pid, Reason, MSL, SName) ->
 %%-----------------------------------------------------------------
 %% Callback functions for system messages handling.
 %%-----------------------------------------------------------------
-system_continue(Parent, Debug, [ServerName, MSL, Hib]) ->
-    loop(Parent, ServerName, MSL, Debug, Hib).
+system_continue(Parent, Debug, [ServerName, MSL, AutoHibernateTimeout, Hib]) ->
+    loop(Parent, ServerName, MSL, AutoHibernateTimeout, Debug, Hib).
 
 -spec system_terminate(_, _, _, [_]) -> no_return().
-system_terminate(Reason, Parent, _Debug, [ServerName, MSL, _Hib]) ->
+system_terminate(Reason, Parent, _Debug, [ServerName, MSL, _AutoHibernateTimeout, _Hib]) ->
     terminate_server(Reason, Parent, MSL, ServerName).
 
 %%-----------------------------------------------------------------
 %% Module here is sent in the system msg change_code.  It specifies
 %% which module should be changed.
 %%-----------------------------------------------------------------
-system_code_change([ServerName, MSL, Hib], Module, OldVsn, Extra) ->
+system_code_change([ServerName, MSL, AutoHibernateTimeout, Hib], Module, OldVsn, Extra) ->
     MSL1 = lists:zf(fun(H) when H#handler.module =:= Module ->
 			    {ok, NewState} =
 				Module:code_change(OldVsn,
@@ -412,12 +415,12 @@ system_code_change([ServerName, MSL, Hib], Module, OldVsn, Extra) ->
 		       (_) -> true
 		    end,
 		    MSL),
-    {ok, [ServerName, MSL1, Hib]}.
+    {ok, [ServerName, MSL1, AutoHibernateTimeout, Hib]}.
 
-system_get_state([_ServerName, MSL, _Hib]) ->
+system_get_state([_ServerName, MSL, _AutoHibernateTimeout, _Hib]) ->
     {ok, [{Mod,Id,State} || #handler{module=Mod, id=Id, state=State} <- MSL]}.
 
-system_replace_state(StateFun, [ServerName, MSL, Hib]) ->
+system_replace_state(StateFun, [ServerName, MSL, AutoHibernateTimeout, Hib]) ->
     {NMSL, NStates} =
 		lists:unzip([begin
 				 Cur = {Mod,Id,State},
@@ -429,7 +432,7 @@ system_replace_state(StateFun, [ServerName, MSL, Hib]) ->
 					 {HS, Cur}
 				 end
 			     end || #handler{module=Mod, id=Id, state=State}=HS <- MSL]),
-    {ok, NStates, [ServerName, NMSL, Hib]}.
+    {ok, NStates, [ServerName, NMSL, AutoHibernateTimeout, Hib]}.
 
 %%-----------------------------------------------------------------
 %% Format debug messages.  Print them as the call-back module sees
@@ -798,7 +801,7 @@ get_modules(MSL) ->
 %% Status information
 %%-----------------------------------------------------------------
 format_status(Opt, StatusData) ->
-    [PDict, SysState, Parent, _Debug, [ServerName, MSL, _Hib]] = StatusData,
+    [PDict, SysState, Parent, _Debug, [ServerName, MSL, _AutoHibernateTimeout, _Hib]] = StatusData,
     Header = gen:format_status_header("Status for event handler",
                                       ServerName),
     FmtMSL = [case erlang:function_exported(Mod, format_status, 2) of
diff --git a/lib/stdlib/src/gen_fsm.erl b/lib/stdlib/src/gen_fsm.erl
index d413da3ea1..8da79c41f9 100644
--- a/lib/stdlib/src/gen_fsm.erl
+++ b/lib/stdlib/src/gen_fsm.erl
@@ -113,7 +113,7 @@
 	 sync_send_all_state_event/2, sync_send_all_state_event/3,
 	 reply/2,
 	 start_timer/2,send_event_after/2,cancel_timer/1,
-	 enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/6]).
+	 enter_loop/4, enter_loop/5, enter_loop/6, wake_hib/7]).
 
 %% Internal exports
 -export([init_it/6,
@@ -329,7 +329,8 @@ enter_loop(Mod, Options, StateName, StateData, ServerName, Timeout) ->
     Name = gen:get_proc_name(ServerName),
     Parent = gen:get_parent(),
     Debug = gen:debug_options(Name, Options),
-    loop(Parent, Name, StateName, StateData, Mod, Timeout, Debug).
+	AutoHibernateTimeout = gen:auto_hibernate_timeout(Options),
+    loop(Parent, Name, StateName, StateData, Mod, Timeout, AutoHibernateTimeout, Debug).
 
 %%% ---------------------------------------------------
 %%% Initiate the new process.
@@ -343,13 +344,14 @@ init_it(Starter, self, Name, Mod, Args, Options) ->
 init_it(Starter, Parent, Name0, Mod, Args, Options) ->
     Name = gen:name(Name0),
     Debug = gen:debug_options(Name, Options),
-    case catch Mod:init(Args) of
+	AutoHibernateTimeout = gen:auto_hibernate_timeout(Options),
+	case catch Mod:init(Args) of
 	{ok, StateName, StateData} ->
 	    proc_lib:init_ack(Starter, {ok, self()}), 	    
-	    loop(Parent, Name, StateName, StateData, Mod, infinity, Debug);
+	    loop(Parent, Name, StateName, StateData, Mod, infinity, AutoHibernateTimeout, Debug);
 	{ok, StateName, StateData, Timeout} ->
 	    proc_lib:init_ack(Starter, {ok, self()}), 	    
-	    loop(Parent, Name, StateName, StateData, Mod, Timeout, Debug);
+	    loop(Parent, Name, StateName, StateData, Mod, Timeout, AutoHibernateTimeout, Debug);
 	{stop, Reason} ->
 	    gen:unregister_name(Name0),
 	    proc_lib:init_ack(Starter, {error, Reason}),
@@ -371,68 +373,77 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
 %%-----------------------------------------------------------------
 %% The MAIN loop
 %%-----------------------------------------------------------------
-loop(Parent, Name, StateName, StateData, Mod, hibernate, Debug) ->
+loop(Parent, Name, StateName, StateData, Mod, hibernate, AutoHibernateTimeout, Debug) ->
     proc_lib:hibernate(?MODULE,wake_hib,
-		       [Parent, Name, StateName, StateData, Mod, 
+		       [Parent, Name, StateName, StateData, Mod, AutoHibernateTimeout,
 			Debug]);
-loop(Parent, Name, StateName, StateData, Mod, Time, Debug) ->
+
+loop(Parent, Name, StateName, StateData, Mod, infinity, AutoHibernateTimeout, Debug) ->
+	receive
+		Msg ->
+			decode_msg(Msg,Parent, Name, StateName, StateData, Mod, infinity, AutoHibernateTimeout, Debug, false)
+	after AutoHibernateTimeout ->
+		proc_lib:hibernate(?MODULE,wake_hib, [Parent, Name, StateName, StateData, Mod, AutoHibernateTimeout, Debug])
+	end;
+
+loop(Parent, Name, StateName, StateData, Mod, Time, AutoHibernateTimeout, Debug) ->
     Msg = receive
 	      Input ->
 		    Input
 	  after Time ->
 		  {'$gen_event', timeout}
 	  end,
-    decode_msg(Msg,Parent, Name, StateName, StateData, Mod, Time, Debug, false).
+    decode_msg(Msg,Parent, Name, StateName, StateData, Mod, Time, AutoHibernateTimeout, Debug, false).
 
-wake_hib(Parent, Name, StateName, StateData, Mod, Debug) ->
+wake_hib(Parent, Name, StateName, StateData, Mod, AutoHibernateTimeout, Debug) ->
     Msg = receive
 	      Input ->
 		  Input
 	  end,
-    decode_msg(Msg, Parent, Name, StateName, StateData, Mod, hibernate, Debug, true).
+    decode_msg(Msg, Parent, Name, StateName, StateData, Mod, hibernate, AutoHibernateTimeout, Debug, true).
 
-decode_msg(Msg,Parent, Name, StateName, StateData, Mod, Time, Debug, Hib) ->
+decode_msg(Msg,Parent, Name, StateName, StateData, Mod, Time, AutoHibernateTimeout, Debug, Hib) ->
     case Msg of
         {system, From, Req} ->
 	    sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug,
-				  [Name, StateName, StateData, Mod, Time], Hib);
+				  [Name, StateName, StateData, Mod, Time, AutoHibernateTimeout], Hib);
 	{'EXIT', Parent, Reason} ->
 	    terminate(Reason, Name, Msg, Mod, StateName, StateData, Debug);
 	_Msg when Debug =:= [] ->
-	    handle_msg(Msg, Parent, Name, StateName, StateData, Mod, Time);
+	    handle_msg(Msg, Parent, Name, StateName, StateData, Mod, Time, AutoHibernateTimeout);
 	_Msg ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
 				      {Name, StateName}, {in, Msg}),
 	    handle_msg(Msg, Parent, Name, StateName, StateData,
-		       Mod, Time, Debug1)
+		       Mod, Time, AutoHibernateTimeout, Debug1)
     end.
 
 %%-----------------------------------------------------------------
 %% Callback functions for system messages handling.
 %%-----------------------------------------------------------------
-system_continue(Parent, Debug, [Name, StateName, StateData, Mod, Time]) ->
-    loop(Parent, Name, StateName, StateData, Mod, Time, Debug).
+system_continue(Parent, Debug, [Name, StateName, StateData, Mod, Time, AutoHibernateTimeout]) ->
+    loop(Parent, Name, StateName, StateData, Mod, Time, AutoHibernateTimeout, Debug).
 
 -spec system_terminate(term(), _, _, [term(),...]) -> no_return().
 
 system_terminate(Reason, _Parent, Debug,
-		 [Name, StateName, StateData, Mod, _Time]) ->
+		 [Name, StateName, StateData, Mod, _Time, _AutoHibernateTimeout]) ->
     terminate(Reason, Name, [], Mod, StateName, StateData, Debug).
 
-system_code_change([Name, StateName, StateData, Mod, Time],
+system_code_change([Name, StateName, StateData, Mod, Time, AutoHibernateTimeout],
 		   _Module, OldVsn, Extra) ->
     case catch Mod:code_change(OldVsn, StateName, StateData, Extra) of
 	{ok, NewStateName, NewStateData} ->
-	    {ok, [Name, NewStateName, NewStateData, Mod, Time]};
+	    {ok, [Name, NewStateName, NewStateData, Mod, Time, AutoHibernateTimeout]};
 	Else -> Else
     end.
 
-system_get_state([_Name, StateName, StateData, _Mod, _Time]) ->
+system_get_state([_Name, StateName, StateData, _Mod, _Time, _AutoHibernateTimeout]) ->
     {ok, {StateName, StateData}}.
 
-system_replace_state(StateFun, [Name, StateName, StateData, Mod, Time]) ->
+system_replace_state(StateFun, [Name, StateName, StateData, Mod, Time, AutoHibernateTimeout]) ->
     Result = {NStateName, NStateData} = StateFun({StateName, StateData}),
-    {ok, Result, [Name, NStateName, NStateData, Mod, Time]}.
+    {ok, Result, [Name, NStateName, NStateData, Mod, Time, AutoHibernateTimeout]}.
 
 %%-----------------------------------------------------------------
 %% Format debug messages.  Print them as the call-back module sees
@@ -467,19 +478,19 @@ print_event(Dev, return, {Name, StateName}) ->
     io:format(Dev, "*DBG* ~p switched to state ~w~n",
 	      [Name, StateName]).
 
-handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time) -> %No debug here
+handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time, AutoHibernateTimeout) -> %No debug here
     From = from(Msg),
     case catch dispatch(Msg, Mod, StateName, StateData) of
 	{next_state, NStateName, NStateData} ->	    
-	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, []);
+	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, AutoHibernateTimeout, []);
 	{next_state, NStateName, NStateData, Time1} ->
-	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, []);
+	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, AutoHibernateTimeout, []);
         {reply, Reply, NStateName, NStateData} when From =/= undefined ->
 	    reply(From, Reply),
-	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, []);
+	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, AutoHibernateTimeout, []);
         {reply, Reply, NStateName, NStateData, Time1} when From =/= undefined ->
 	    reply(From, Reply),
-	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, []);
+	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, AutoHibernateTimeout, []);
 	{stop, Reason, NStateData} ->
 	    terminate(Reason, Name, Msg, Mod, StateName, NStateData, []);
 	{stop, Reason, Reply, NStateData} when From =/= undefined ->
@@ -498,23 +509,23 @@ handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time) -> %No debug her
 		      Name, Msg, Mod, StateName, StateData, [])
     end.
 
-handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time, Debug) ->
+handle_msg(Msg, Parent, Name, StateName, StateData, Mod, _Time, AutoHibernateTimeout, Debug) ->
     From = from(Msg),
     case catch dispatch(Msg, Mod, StateName, StateData) of
 	{next_state, NStateName, NStateData} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
 				      {Name, NStateName}, return),
-	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, Debug1);
+	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, AutoHibernateTimeout, Debug1);
 	{next_state, NStateName, NStateData, Time1} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
 				      {Name, NStateName}, return),
-	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, Debug1);
+	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, AutoHibernateTimeout, Debug1);
         {reply, Reply, NStateName, NStateData} when From =/= undefined ->
 	    Debug1 = reply(Name, From, Reply, Debug, NStateName),
-	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, Debug1);
+	    loop(Parent, Name, NStateName, NStateData, Mod, infinity, AutoHibernateTimeout, Debug1);
         {reply, Reply, NStateName, NStateData, Time1} when From =/= undefined ->
 	    Debug1 = reply(Name, From, Reply, Debug, NStateName),
-	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, Debug1);
+	    loop(Parent, Name, NStateName, NStateData, Mod, Time1, AutoHibernateTimeout, Debug1);
 	{stop, Reason, NStateData} ->
 	    terminate(Reason, Name, Msg, Mod, StateName, NStateData, Debug);
 	{stop, Reason, Reply, NStateData} when From =/= undefined ->
@@ -645,7 +656,7 @@ get_msg(Msg) -> Msg.
 %% Status information
 %%-----------------------------------------------------------------
 format_status(Opt, StatusData) ->
-    [PDict, SysState, Parent, Debug, [Name, StateName, StateData, Mod, _Time]] =
+    [PDict, SysState, Parent, Debug, [Name, StateName, StateData, Mod, _Time, _AutoHibernateTimeout]] =
 	StatusData,
     Header = gen:format_status_header("Status for state machine",
                                       Name),
diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl
index 8504af86f8..a538e80211 100644
--- a/lib/stdlib/src/gen_server.erl
+++ b/lib/stdlib/src/gen_server.erl
@@ -94,7 +94,7 @@
 	 cast/2, reply/2,
 	 abcast/2, abcast/3,
 	 multi_call/2, multi_call/3, multi_call/4,
-	 enter_loop/3, enter_loop/4, enter_loop/5, wake_hib/5]).
+	 enter_loop/3, enter_loop/4, enter_loop/5, wake_hib/6]).
 
 %% System exports
 -export([system_continue/3,
@@ -307,7 +307,8 @@ enter_loop(Mod, Options, State, ServerName, Timeout) ->
     Name = gen:get_proc_name(ServerName),
     Parent = gen:get_parent(),
     Debug = gen:debug_options(Name, Options),
-    loop(Parent, Name, State, Mod, Timeout, Debug).
+	AutoHibernateTimeout = gen:auto_hibernate_timeout(Options),
+    loop(Parent, Name, State, Mod, Timeout, AutoHibernateTimeout, Debug).
 
 %%%========================================================================
 %%% Gen-callback functions
@@ -325,13 +326,14 @@ init_it(Starter, self, Name, Mod, Args, Options) ->
 init_it(Starter, Parent, Name0, Mod, Args, Options) ->
     Name = gen:name(Name0),
     Debug = gen:debug_options(Name, Options),
+	AutoHibernateTimeout = gen:auto_hibernate_timeout(Options),
     case catch Mod:init(Args) of
 	{ok, State} ->
 	    proc_lib:init_ack(Starter, {ok, self()}), 	    
-	    loop(Parent, Name, State, Mod, infinity, Debug);
+	    loop(Parent, Name, State, Mod, infinity, AutoHibernateTimeout, Debug);
 	{ok, State, Timeout} ->
 	    proc_lib:init_ack(Starter, {ok, self()}), 	    
-	    loop(Parent, Name, State, Mod, Timeout, Debug);
+	    loop(Parent, Name, State, Mod, Timeout, AutoHibernateTimeout, Debug);
 	{stop, Reason} ->
 	    %% For consistency, we must make sure that the
 	    %% registered name (if any) is unregistered before
@@ -362,37 +364,46 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) ->
 %%% ---------------------------------------------------
 %%% The MAIN loop.
 %%% ---------------------------------------------------
-loop(Parent, Name, State, Mod, hibernate, Debug) ->
-    proc_lib:hibernate(?MODULE,wake_hib,[Parent, Name, State, Mod, Debug]);
-loop(Parent, Name, State, Mod, Time, Debug) ->
+loop(Parent, Name, State, Mod, hibernate, AutoHibernateTimeout, Debug) ->
+    proc_lib:hibernate(?MODULE,wake_hib,[Parent, Name, State, Mod, AutoHibernateTimeout, Debug]);
+
+loop(Parent, Name, State, Mod, infinity, AutoHibernateTimeout, Debug) ->
+	receive
+		Msg ->
+			decode_msg(Msg, Parent, Name, State, Mod, infinity, AutoHibernateTimeout, Debug, false)
+	after AutoHibernateTimeout ->
+		proc_lib:hibernate(?MODULE,wake_hib,[Parent, Name, State, Mod, AutoHibernateTimeout, Debug])
+	end;
+
+loop(Parent, Name, State, Mod, Time, AutoHibernateTimeout, Debug) ->
     Msg = receive
 	      Input ->
 		    Input
 	  after Time ->
 		  timeout
 	  end,
-    decode_msg(Msg, Parent, Name, State, Mod, Time, Debug, false).
+    decode_msg(Msg, Parent, Name, State, Mod, Time, AutoHibernateTimeout, Debug, false).
 
-wake_hib(Parent, Name, State, Mod, Debug) ->
+wake_hib(Parent, Name, State, Mod, AutoHibernateTimeout, Debug) ->
     Msg = receive
 	      Input ->
 		  Input
 	  end,
-    decode_msg(Msg, Parent, Name, State, Mod, hibernate, Debug, true).
+    decode_msg(Msg, Parent, Name, State, Mod, hibernate, AutoHibernateTimeout, Debug, true).
 
-decode_msg(Msg, Parent, Name, State, Mod, Time, Debug, Hib) ->
+decode_msg(Msg, Parent, Name, State, Mod, Time, AutoHibernateTimeout, Debug, Hib) ->
     case Msg of
 	{system, From, Req} ->
 	    sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug,
-				  [Name, State, Mod, Time], Hib);
+				  [Name, State, Mod, Time, AutoHibernateTimeout], Hib);
 	{'EXIT', Parent, Reason} ->
 	    terminate(Reason, Name, undefined, Msg, Mod, State, Debug);
 	_Msg when Debug =:= [] ->
-	    handle_msg(Msg, Parent, Name, State, Mod);
+	    handle_msg(Msg, Parent, Name, State, Mod, AutoHibernateTimeout);
 	_Msg ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3,
 				      Name, {in, Msg}),
-	    handle_msg(Msg, Parent, Name, State, Mod, Debug1)
+	    handle_msg(Msg, Parent, Name, State, Mod, AutoHibernateTimeout, Debug1)
     end.
 
 %%% ---------------------------------------------------
@@ -659,65 +670,65 @@ try_terminate(Mod, Reason, State) ->
 %%% Message handling functions
 %%% ---------------------------------------------------
 
-handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod) ->
+handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, AutoHibernateTimeout) ->
     Result = try_handle_call(Mod, Msg, From, State),
     case Result of
 	{ok, {reply, Reply, NState}} ->
 	    reply(From, Reply),
-	    loop(Parent, Name, NState, Mod, infinity, []);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, []);
 	{ok, {reply, Reply, NState, Time1}} ->
 	    reply(From, Reply),
-	    loop(Parent, Name, NState, Mod, Time1, []);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, []);
 	{ok, {noreply, NState}} ->
-	    loop(Parent, Name, NState, Mod, infinity, []);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, []);
 	{ok, {noreply, NState, Time1}} ->
-	    loop(Parent, Name, NState, Mod, Time1, []);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, []);
 	{ok, {stop, Reason, Reply, NState}} ->
 	    {'EXIT', R} = 
 		(catch terminate(Reason, Name, From, Msg, Mod, NState, [])),
 	    reply(From, Reply),
 	    exit(R);
-	Other -> handle_common_reply(Other, Parent, Name, From, Msg, Mod, State)
+	Other -> handle_common_reply(Other, Parent, Name, From, Msg, Mod, AutoHibernateTimeout, State)
     end;
-handle_msg(Msg, Parent, Name, State, Mod) ->
+handle_msg(Msg, Parent, Name, State, Mod, AutoHibernateTimeout) ->
     Reply = try_dispatch(Msg, Mod, State),
-    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, State).
+    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, AutoHibernateTimeout, State).
 
-handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, Debug) ->
+handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, AutoHibernateTimeout, Debug) ->
     Result = try_handle_call(Mod, Msg, From, State),
     case Result of
 	{ok, {reply, Reply, NState}} ->
 	    Debug1 = reply(Name, From, Reply, NState, Debug),
-	    loop(Parent, Name, NState, Mod, infinity, Debug1);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, Debug1);
 	{ok, {reply, Reply, NState, Time1}} ->
 	    Debug1 = reply(Name, From, Reply, NState, Debug),
-	    loop(Parent, Name, NState, Mod, Time1, Debug1);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, Debug1);
 	{ok, {noreply, NState}} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
 				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, infinity, Debug1);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, Debug1);
 	{ok, {noreply, NState, Time1}} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
 				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, Time1, Debug1);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, Debug1);
 	{ok, {stop, Reason, Reply, NState}} ->
 	    {'EXIT', R} = 
 		(catch terminate(Reason, Name, From, Msg, Mod, NState, Debug)),
 	    _ = reply(Name, From, Reply, NState, Debug),
 	    exit(R);
 	Other ->
-	    handle_common_reply(Other, Parent, Name, From, Msg, Mod, State, Debug)
+	    handle_common_reply(Other, Parent, Name, From, Msg, Mod, AutoHibernateTimeout, State, Debug)
     end;
-handle_msg(Msg, Parent, Name, State, Mod, Debug) ->
+handle_msg(Msg, Parent, Name, State, Mod, AutoHibernateTimeout, Debug) ->
     Reply = try_dispatch(Msg, Mod, State),
-    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, State, Debug).
+    handle_common_reply(Reply, Parent, Name, undefined, Msg, Mod, AutoHibernateTimeout, State, Debug).
 
-handle_common_reply(Reply, Parent, Name, From, Msg, Mod, State) ->
+handle_common_reply(Reply, Parent, Name, From, Msg, Mod, AutoHibernateTimeout, State) ->
     case Reply of
 	{ok, {noreply, NState}} ->
-	    loop(Parent, Name, NState, Mod, infinity, []);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, []);
 	{ok, {noreply, NState, Time1}} ->
-	    loop(Parent, Name, NState, Mod, Time1, []);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, []);
 	{ok, {stop, Reason, NState}} ->
 	    terminate(Reason, Name, From, Msg, Mod, NState, []);
 	{'EXIT', ExitReason, ReportReason} ->
@@ -726,16 +737,16 @@ handle_common_reply(Reply, Parent, Name, From, Msg, Mod, State) ->
 	    terminate({bad_return_value, BadReply}, Name, From, Msg, Mod, State, [])
     end.
 
-handle_common_reply(Reply, Parent, Name, From, Msg, Mod, State, Debug) ->
+handle_common_reply(Reply, Parent, Name, From, Msg, Mod, AutoHibernateTimeout, State, Debug) ->
     case Reply of
 	{ok, {noreply, NState}} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
 				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, infinity, Debug1);
+	    loop(Parent, Name, NState, Mod, infinity, AutoHibernateTimeout, Debug1);
 	{ok, {noreply, NState, Time1}} ->
 	    Debug1 = sys:handle_debug(Debug, fun print_event/3, Name,
 				      {noreply, NState}),
-	    loop(Parent, Name, NState, Mod, Time1, Debug1);
+	    loop(Parent, Name, NState, Mod, Time1, AutoHibernateTimeout, Debug1);
 	{ok, {stop, Reason, NState}} ->
 	    terminate(Reason, Name, From, Msg, Mod, NState, Debug);
 	{'EXIT', ExitReason, ReportReason} ->
@@ -753,26 +764,26 @@ reply(Name, {To, Tag}, Reply, State, Debug) ->
 %%-----------------------------------------------------------------
 %% Callback functions for system messages handling.
 %%-----------------------------------------------------------------
-system_continue(Parent, Debug, [Name, State, Mod, Time]) ->
-    loop(Parent, Name, State, Mod, Time, Debug).
+system_continue(Parent, Debug, [Name, State, Mod, Time, AutoHibernateTimeout]) ->
+    loop(Parent, Name, State, Mod, Time, AutoHibernateTimeout, Debug).
 
 -spec system_terminate(_, _, _, [_]) -> no_return().
 
-system_terminate(Reason, _Parent, Debug, [Name, State, Mod, _Time]) ->
+system_terminate(Reason, _Parent, Debug, [Name, State, Mod, _Time, _AutoHibernateTimeout]) ->
     terminate(Reason, Name, undefined, [], Mod, State, Debug).
 
-system_code_change([Name, State, Mod, Time], _Module, OldVsn, Extra) ->
+system_code_change([Name, State, Mod, Time, AutoHibernateTimeout], _Module, OldVsn, Extra) ->
     case catch Mod:code_change(OldVsn, State, Extra) of
-	{ok, NewState} -> {ok, [Name, NewState, Mod, Time]};
+	{ok, NewState} -> {ok, [Name, NewState, Mod, Time, AutoHibernateTimeout]};
 	Else -> Else
     end.
 
-system_get_state([_Name, State, _Mod, _Time]) ->
+system_get_state([_Name, State, _Mod, _Time, _AutoHibernateTimeout]) ->
     {ok, State}.
 
-system_replace_state(StateFun, [Name, State, Mod, Time]) ->
+system_replace_state(StateFun, [Name, State, Mod, Time, AutoHibernateTimeout]) ->
     NState = StateFun(State),
-    {ok, NState, [Name, NState, Mod, Time]}.
+    {ok, NState, [Name, NState, Mod, Time, AutoHibernateTimeout]}.
 
 %%-----------------------------------------------------------------
 %% Format debug messages.  Print them as the call-back module sees
@@ -802,10 +813,10 @@ print_event(Dev, Event, Name) ->
 %%% Terminate the server.
 %%% ---------------------------------------------------
 
+
 -spec terminate(_, _, _, _, _, _, _) -> no_return().
 terminate(Reason, Name, From, Msg, Mod, State, Debug) ->
     terminate(Reason, Reason, Name, From, Msg, Mod, State, Debug).
-
 -spec terminate(_, _, _, _, _, _, _, _) -> no_return().
 terminate(ExitReason, ReportReason, Name, From, Msg, Mod, State, Debug) ->
     Reply = try_terminate(Mod, ExitReason, State),
@@ -851,7 +862,7 @@ error_info(Reason, Name, From, Msg, State, Debug) ->
 		end;
 	    _ ->
 		Reason
-	end,
+	end,    
     {ClientFmt, ClientArgs} = client_stacktrace(From),
     format("** Generic server ~p terminating \n"
            "** Last message in was ~p~n"
@@ -860,7 +871,6 @@ error_info(Reason, Name, From, Msg, State, Debug) ->
 	   [Name, Msg, State, Reason1] ++ ClientArgs),
     sys:print_log(Debug),
     ok.
-
 client_stacktrace(undefined) ->
     {"", []};
 client_stacktrace({From, _Tag}) ->
@@ -885,7 +895,7 @@ client_stacktrace(From) when is_pid(From) ->
 %% Status information
 %%-----------------------------------------------------------------
 format_status(Opt, StatusData) ->
-    [PDict, SysState, Parent, Debug, [Name, State, Mod, _Time]] = StatusData,
+    [PDict, SysState, Parent, Debug, [Name, State, Mod, _Time, _AutoHibernateTimeout]] = StatusData,
     Header = gen:format_status_header("Status for generic server", Name),
     Log = sys:get_debug(log, Debug, []),
     Specfic = case format_status(Opt, Mod, PDict, State) of