merging bug 21457 into default

10 files changed, 341 insertions, 439 deletions

diff --git a/ebin/rabbit_app.in b/ebin/rabbit_app.in
index dd907d1a..39f98cbe 100644
--- a/ebin/rabbit_app.in
+++ b/ebin/rabbit_app.in
@@ -20,5 +20,4 @@
          {default_user, <<"guest">>},
          {default_pass, <<"guest">>},
          {default_vhost, <<"/">>},
-         {default_permissions, [<<".*">>, <<".*">>, <<".*">>]},
-         {memory_alarms, auto}]}]}.
+         {default_permissions, [<<".*">>, <<".*">>, <<".*">>]}]}]}.
diff --git a/scripts/rabbitmq-server b/scripts/rabbitmq-server
index 67768c0e..08ceb27d 100755
--- a/scripts/rabbitmq-server
+++ b/scripts/rabbitmq-server
@@ -109,9 +109,7 @@ exec erl \
     -os_mon start_cpu_sup true \
     -os_mon start_disksup false \
     -os_mon start_memsup false \
-    -os_mon start_os_sup false \
-    -os_mon memsup_system_only true \
-    -os_mon system_memory_high_watermark 0.95 \
+    -os_mon vm_memory_high_watermark 0.7 \
     -mnesia dir "\"${RABBITMQ_MNESIA_DIR}\"" \
     ${RABBITMQ_CLUSTER_CONFIG_OPTION} \
     ${RABBITMQ_SERVER_START_ARGS} \
diff --git a/scripts/rabbitmq-server.bat b/scripts/rabbitmq-server.bat
index b45a2713..7cd3a33f 100755
--- a/scripts/rabbitmq-server.bat
+++ b/scripts/rabbitmq-server.bat
@@ -138,9 +138,7 @@ if exist "%RABBITMQ_CONFIG_FILE%.config" (
 -os_mon start_cpu_sup true ^

 -os_mon start_disksup false ^

 -os_mon start_memsup false ^

--os_mon start_os_sup false ^

--os_mon memsup_system_only true ^

--os_mon system_memory_high_watermark 0.95 ^

+-os_mon vm_memory_high_watermark 0.7 ^

 -mnesia dir \""%RABBITMQ_MNESIA_DIR%"\" ^

 %CLUSTER_CONFIG% ^

 %RABBITMQ_SERVER_START_ARGS% ^

diff --git a/scripts/rabbitmq-service.bat b/scripts/rabbitmq-service.bat
index 3a30ea26..f882da8a 100755
--- a/scripts/rabbitmq-service.bat
+++ b/scripts/rabbitmq-service.bat
@@ -173,9 +173,7 @@ set ERLANG_SERVICE_ARGUMENTS= ^
 -os_mon start_cpu_sup true ^

 -os_mon start_disksup false ^

 -os_mon start_memsup false ^

--os_mon start_os_sup false ^

--os_mon memsup_system_only true ^

--os_mon system_memory_high_watermark 0.95 ^

+-os_mon vm_memory_high_watermark 0.7 ^

 -mnesia dir \""%RABBITMQ_MNESIA_DIR%"\" ^

 %CLUSTER_CONFIG% ^

 %RABBITMQ_SERVER_START_ARGS% ^

diff --git a/src/rabbit.erl b/src/rabbit.erl
index 18fd1b17..092ca3c9 100644
--- a/src/rabbit.erl
+++ b/src/rabbit.erl
@@ -140,8 +140,16 @@ start(normal, []) ->
                 ok = rabbit_binary_generator:
                     check_empty_content_body_frame_size(),
 
-                {ok, MemoryAlarms} = application:get_env(memory_alarms),
-                ok = rabbit_alarm:start(MemoryAlarms),
+                ok = rabbit_alarm:start(),
+                MemoryWatermark = 
+                    application:get_env(os_mon, vm_memory_high_watermark),
+                ok = case MemoryWatermark of
+                         {ok, Float} when Float == 0 -> ok;
+                         {ok, Float} -> start_child(vm_memory_monitor, [Float]);
+                         undefined ->
+                             throw({undefined, os_mon,
+                                    vm_memory_high_watermark, settings})
+                     end,
                 
                 ok = rabbit_amqqueue:start(),
 
@@ -264,8 +272,11 @@ print_banner() ->
     io:nl().
 
 start_child(Mod) ->
+    start_child(Mod, []).
+
+start_child(Mod, Args) ->
     {ok,_} = supervisor:start_child(rabbit_sup,
-                                    {Mod, {Mod, start_link, []},
+                                    {Mod, {Mod, start_link, Args},
                                      transient, 100, worker, [Mod]}),
     ok.
 
diff --git a/src/rabbit_alarm.erl b/src/rabbit_alarm.erl
index 7a2fbcb8..9a639ed4 100644
--- a/src/rabbit_alarm.erl
+++ b/src/rabbit_alarm.erl
@@ -33,24 +33,19 @@
 
 -behaviour(gen_event).
 
--export([start/1, stop/0, register/2]).
+-export([start/0, stop/0, register/2]).
 
 -export([init/1, handle_call/2, handle_event/2, handle_info/2,
          terminate/2, code_change/3]).
 
--define(MEMSUP_CHECK_INTERVAL, 1000).
-
-%% OSes on which we know memory alarms to be trustworthy
--define(SUPPORTED_OS, [{unix, linux}, {unix, darwin}]).
-
--record(alarms, {alertees, system_memory_high_watermark = false}).
+-record(alarms, {alertees, vm_memory_high_watermark = false}).
 
 %%----------------------------------------------------------------------------
 
 -ifdef(use_specs).
 
 -type(mfa_tuple() :: {atom(), atom(), list()}).
--spec(start/1 :: (boolean() | 'auto') -> 'ok').
+-spec(start/0 :: () -> 'ok').
 -spec(stop/0 :: () -> 'ok').
 -spec(register/2 :: (pid(), mfa_tuple()) -> 'ok').
 
@@ -58,20 +53,8 @@
 
 %%----------------------------------------------------------------------------
 
-start(MemoryAlarms) ->
-    EnableAlarms = case MemoryAlarms of
-                       true  -> true;
-                       false -> false;
-                       auto  -> lists:member(os:type(), ?SUPPORTED_OS)
-                   end,
-    ok = alarm_handler:add_alarm_handler(?MODULE, [EnableAlarms]),
-    case whereis(memsup) of
-        undefined -> if EnableAlarms -> ok = start_memsup(),
-                                        ok = adjust_memsup_interval();
-                        true         -> ok
-                     end;
-        _         -> ok = adjust_memsup_interval()
-    end.
+start() ->
+    ok = alarm_handler:add_alarm_handler(?MODULE, []).
 
 stop() ->
     ok = alarm_handler:delete_alarm_handler(?MODULE).
@@ -83,43 +66,33 @@ register(Pid, HighMemMFA) ->
 
 %%----------------------------------------------------------------------------
 
-init([MemoryAlarms]) ->
-    {ok, #alarms{alertees = case MemoryAlarms of
-                                true  -> dict:new();
-                                false -> undefined
-                            end}}.
+init([]) ->
+    {ok, #alarms{alertees = dict:new()}}.
 
-handle_call({register, _Pid, _HighMemMFA},
-            State = #alarms{alertees = undefined}) ->
-    {ok, ok, State};
-handle_call({register, Pid, HighMemMFA},
+handle_call({register, Pid, {M, F, A} = HighMemMFA},
             State = #alarms{alertees = Alertess}) ->
     _MRef = erlang:monitor(process, Pid),
-    case State#alarms.system_memory_high_watermark of
-        true  -> {M, F, A} = HighMemMFA,
-                 ok = erlang:apply(M, F, A ++ [Pid, true]);
-        false -> ok
-    end,
+    ok = case State#alarms.vm_memory_high_watermark of
+             true  -> apply(M, F, A ++ [Pid, true]);
+             false -> ok
+         end,
     NewAlertees = dict:store(Pid, HighMemMFA, Alertess),
     {ok, ok, State#alarms{alertees = NewAlertees}};
 
 handle_call(_Request, State) ->
     {ok, not_understood, State}.
 
-handle_event({set_alarm, {system_memory_high_watermark, []}}, State) ->
+handle_event({set_alarm, {vm_memory_high_watermark, []}}, State) ->
     ok = alert(true, State#alarms.alertees),
-    {ok, State#alarms{system_memory_high_watermark = true}};
+    {ok, State#alarms{vm_memory_high_watermark = true}};
 
-handle_event({clear_alarm, system_memory_high_watermark}, State) ->
+handle_event({clear_alarm, vm_memory_high_watermark}, State) ->
     ok = alert(false, State#alarms.alertees),
-    {ok, State#alarms{system_memory_high_watermark = false}};
+    {ok, State#alarms{vm_memory_high_watermark = false}};
 
 handle_event(_Event, State) ->
     {ok, State}.
 
-handle_info({'DOWN', _MRef, process, _Pid, _Reason},
-            State = #alarms{alertees = undefined}) ->
-    {ok, State};
 handle_info({'DOWN', _MRef, process, Pid, _Reason},
             State = #alarms{alertees = Alertess}) ->
     {ok, State#alarms{alertees = dict:erase(Pid, Alertess)}};
@@ -134,57 +107,6 @@ code_change(_OldVsn, State, _Extra) ->
     {ok, State}.
 
 %%----------------------------------------------------------------------------
-
-start_memsup() ->
-    {Mod, Args} =
-        case os:type() of
-            %% memsup doesn't take account of buffers or cache when
-            %% considering "free" memory - therefore on Linux we can
-            %% get memory alarms very easily without any pressure
-            %% existing on memory at all. Therefore we need to use
-            %% our own simple memory monitor.
-            %%
-            {unix, linux}  -> {rabbit_memsup, [rabbit_memsup_linux]};
-            {unix, darwin} -> {rabbit_memsup, [rabbit_memsup_darwin]};
-
-            %% Start memsup programmatically rather than via the
-            %% rabbitmq-server script. This is not quite the right
-            %% thing to do as os_mon checks to see if memsup is
-            %% available before starting it, but as memsup is
-            %% available everywhere (even on VXWorks) it should be
-            %% ok.
-            %%
-            %% One benefit of the programmatic startup is that we
-            %% can add our alarm_handler before memsup is running,
-            %% thus ensuring that we notice memory alarms that go
-            %% off on startup.
-            %%
-            _              -> {memsup, []}
-        end,
-    %% This is based on os_mon:childspec(memsup, true)
-    {ok, _} = supervisor:start_child(
-                os_mon_sup,
-                {memsup, {Mod, start_link, Args},
-                 permanent, 2000, worker, [Mod]}),
-    ok.
-
-adjust_memsup_interval() ->
-    %% The default memsup check interval is 1 minute, which is way too
-    %% long - rabbit can gobble up all memory in a matter of seconds.
-    %% Unfortunately the memory_check_interval configuration parameter
-    %% and memsup:set_check_interval/1 function only provide a
-    %% granularity of minutes. So we have to peel off one layer of the
-    %% API to get to the underlying layer which operates at the
-    %% granularity of milliseconds.
-    %%
-    %% Note that the new setting will only take effect after the first
-    %% check has completed, i.e. after one minute. So if rabbit eats
-    %% all the memory within the first minute after startup then we
-    %% are out of luck.
-    ok = os_mon:call(memsup,
-                     {set_check_interval, ?MEMSUP_CHECK_INTERVAL},
-                     infinity).
-
 alert(_Alert, undefined) ->
     ok;
 alert(Alert, Alertees) ->
diff --git a/src/rabbit_memsup.erl b/src/rabbit_memsup.erl
deleted file mode 100644
index b0d57cb2..00000000
--- a/src/rabbit_memsup.erl
+++ /dev/null
@@ -1,142 +0,0 @@
-%%   The contents of this file are subject to the Mozilla Public License
-%%   Version 1.1 (the "License"); you may not use this file except in
-%%   compliance with the License. You may obtain a copy of the License at
-%%   http://www.mozilla.org/MPL/
-%%
-%%   Software distributed under the License is distributed on an "AS IS"
-%%   basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
-%%   License for the specific language governing rights and limitations
-%%   under the License.
-%%
-%%   The Original Code is RabbitMQ.
-%%
-%%   The Initial Developers of the Original Code are LShift Ltd,
-%%   Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
-%%   Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
-%%   are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
-%%   Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
-%%   Ltd. Portions created by Cohesive Financial Technologies LLC are
-%%   Copyright (C) 2007-2009 Cohesive Financial Technologies
-%%   LLC. Portions created by Rabbit Technologies Ltd are Copyright
-%%   (C) 2007-2009 Rabbit Technologies Ltd.
-%%
-%%   All Rights Reserved.
-%%
-%%   Contributor(s): ______________________________________.
-%%
-
--module(rabbit_memsup).
-
--behaviour(gen_server).
-
--export([start_link/1]).
-
--export([init/1, handle_call/3, handle_cast/2, handle_info/2,
-         terminate/2, code_change/3]).
-
--export([update/0]).
-
--record(state, {memory_fraction,
-                timeout,
-                timer,
-                mod,
-                mod_state,
-                alarmed
-               }).
-
--define(SERVER, memsup). %% must be the same as the standard memsup
-
--define(DEFAULT_MEMORY_CHECK_INTERVAL, 1000).
-
-%%----------------------------------------------------------------------------
-
--ifdef(use_specs).
-
--spec(start_link/1 :: (atom()) -> {'ok', pid()} | 'ignore' | {'error', any()}).
--spec(update/0 :: () -> 'ok').
-     
--endif.
-
-%%----------------------------------------------------------------------------
-
-start_link(Args) ->
-    gen_server:start_link({local, ?SERVER}, ?MODULE, [Args], []).
-
-update() ->
-    gen_server:cast(?SERVER, update).
-
-%%----------------------------------------------------------------------------
-
-init([Mod]) -> 
-    Fraction = os_mon:get_env(memsup, system_memory_high_watermark),
-    TRef = start_timer(?DEFAULT_MEMORY_CHECK_INTERVAL),
-    InitState = Mod:init(),
-    State = #state { memory_fraction = Fraction,
-                     timeout = ?DEFAULT_MEMORY_CHECK_INTERVAL,
-                     timer = TRef,
-                     mod = Mod,
-                     mod_state = InitState,
-                     alarmed = false },
-    {ok, internal_update(State)}.
-
-start_timer(Timeout) ->
-    {ok, TRef} = timer:apply_interval(Timeout, ?MODULE, update, []),
-    TRef.
-
-%% Export the same API as the real memsup. Note that
-%% get_sysmem_high_watermark gives an int in the range 0 - 100, while
-%% set_sysmem_high_watermark takes a float in the range 0.0 - 1.0.
-handle_call(get_sysmem_high_watermark, _From, State) ->
-    {reply, trunc(100 * State#state.memory_fraction), State};
-
-handle_call({set_sysmem_high_watermark, Float}, _From, State) ->
-    {reply, ok, State#state{memory_fraction = Float}};
-
-handle_call(get_check_interval, _From, State) ->
-    {reply, State#state.timeout, State};
-
-handle_call({set_check_interval, Timeout}, _From, State) ->
-    {ok, cancel} = timer:cancel(State#state.timer),
-    {reply, ok, State#state{timeout = Timeout, timer = start_timer(Timeout)}};
-
-handle_call(get_memory_data, _From,
-            State = #state { mod = Mod, mod_state = ModState }) ->
-    {reply, Mod:get_memory_data(ModState), State};
-
-handle_call(_Request, _From, State) ->
-    {noreply, State}.
-
-handle_cast(update, State) ->
-    {noreply, internal_update(State)};
-
-handle_cast(_Request, State) -> 
-    {noreply, State}.
-
-handle_info(_Info, State) -> 
-    {noreply, State}.
-
-terminate(_Reason, _State) -> 
-    ok.
-
-code_change(_OldVsn, State, _Extra) -> 
-    {ok, State}.
- 
-internal_update(State = #state { memory_fraction = MemoryFraction,
-                                 alarmed = Alarmed,
-                                 mod = Mod, mod_state = ModState }) ->
-    ModState1 = Mod:update(ModState),
-    {MemTotal, MemUsed, _BigProc} = Mod:get_memory_data(ModState1),
-    NewAlarmed = MemUsed / MemTotal > MemoryFraction,
-    case {Alarmed, NewAlarmed} of
-        {false, true} ->
-            alarm_handler:set_alarm({system_memory_high_watermark, []});
-        {true, false} ->
-            alarm_handler:clear_alarm(system_memory_high_watermark);
-        _ ->
-            ok
-    end,    
-    State #state { mod_state = ModState1, alarmed = NewAlarmed }.
diff --git a/src/rabbit_memsup_darwin.erl b/src/rabbit_memsup_darwin.erl
deleted file mode 100644
index 3de2d843..00000000
--- a/src/rabbit_memsup_darwin.erl
+++ /dev/null
@@ -1,88 +0,0 @@
-%%   The contents of this file are subject to the Mozilla Public License
-%%   Version 1.1 (the "License"); you may not use this file except in
-%%   compliance with the License. You may obtain a copy of the License at
-%%   http://www.mozilla.org/MPL/
-%%
-%%   Software distributed under the License is distributed on an "AS IS"
-%%   basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
-%%   License for the specific language governing rights and limitations
-%%   under the License.
-%%
-%%   The Original Code is RabbitMQ.
-%%
-%%   The Initial Developers of the Original Code are LShift Ltd,
-%%   Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
-%%   Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
-%%   are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
-%%   Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
-%%   Ltd. Portions created by Cohesive Financial Technologies LLC are
-%%   Copyright (C) 2007-2009 Cohesive Financial Technologies
-%%   LLC. Portions created by Rabbit Technologies Ltd are Copyright
-%%   (C) 2007-2009 Rabbit Technologies Ltd.
-%%
-%%   All Rights Reserved.
-%%
-%%   Contributor(s): ______________________________________.
-%%
-
--module(rabbit_memsup_darwin).
-
--export([init/0, update/1, get_memory_data/1]).
-
--record(state, {total_memory,
-                allocated_memory}).
-
-%%----------------------------------------------------------------------------
-
--ifdef(use_specs).
-
--type(state() :: #state { total_memory :: ('undefined' | non_neg_integer()),
-                          allocated_memory :: ('undefined' | non_neg_integer())
-                        }).
-
--spec(init/0 :: () -> state()).
--spec(update/1 :: (state()) -> state()).
--spec(get_memory_data/1 :: (state()) -> {non_neg_integer(), non_neg_integer(),
-                                         ('undefined' | pid())}).
-
--endif.
-
-%%----------------------------------------------------------------------------
-
-init() -> 
-    #state{total_memory = undefined,
-           allocated_memory = undefined}.
-
-update(State) ->
-    File = os:cmd("/usr/bin/vm_stat"),
-    Lines = string:tokens(File, "\n"),
-    Dict = dict:from_list(lists:map(fun parse_line/1, Lines)),
-    [PageSize, Inactive, Active, Free, Wired] =
-        [dict:fetch(Key, Dict) ||
-            Key <- [page_size, 'Pages inactive', 'Pages active', 'Pages free',
-                    'Pages wired down']],
-    MemTotal = PageSize * (Inactive + Active + Free + Wired),
-    MemUsed = PageSize * (Active + Wired),
-    State#state{total_memory = MemTotal, allocated_memory = MemUsed}.
-
-get_memory_data(State) ->
-    {State#state.total_memory, State#state.allocated_memory, undefined}.
-
-%%----------------------------------------------------------------------------
-
-%% A line looks like "Foo bar: 123456."
-parse_line(Line) ->
-    [Name, RHS | _Rest] = string:tokens(Line, ":"),
-    case Name of
-        "Mach Virtual Memory Statistics" ->
-            ["(page", "size", "of", PageSize, "bytes)"] =
-                string:tokens(RHS, " "),
-            {page_size, list_to_integer(PageSize)};
-        _ ->
-            [Value | _Rest1] = string:tokens(RHS, " ."),
-            {list_to_atom(Name), list_to_integer(Value)}
-    end.
diff --git a/src/rabbit_memsup_linux.erl b/src/rabbit_memsup_linux.erl
deleted file mode 100644
index ca942d7c..00000000
--- a/src/rabbit_memsup_linux.erl
+++ /dev/null
@@ -1,101 +0,0 @@
-%%   The contents of this file are subject to the Mozilla Public License
-%%   Version 1.1 (the "License"); you may not use this file except in
-%%   compliance with the License. You may obtain a copy of the License at
-%%   http://www.mozilla.org/MPL/
-%%
-%%   Software distributed under the License is distributed on an "AS IS"
-%%   basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
-%%   License for the specific language governing rights and limitations
-%%   under the License.
-%%
-%%   The Original Code is RabbitMQ.
-%%
-%%   The Initial Developers of the Original Code are LShift Ltd,
-%%   Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
-%%   Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
-%%   are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
-%%   Technologies LLC, and Rabbit Technologies Ltd.
-%%
-%%   Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
-%%   Ltd. Portions created by Cohesive Financial Technologies LLC are
-%%   Copyright (C) 2007-2009 Cohesive Financial Technologies
-%%   LLC. Portions created by Rabbit Technologies Ltd are Copyright
-%%   (C) 2007-2009 Rabbit Technologies Ltd.
-%%
-%%   All Rights Reserved.
-%%
-%%   Contributor(s): ______________________________________.
-%%
-
--module(rabbit_memsup_linux).
-
--export([init/0, update/1, get_memory_data/1]).
-
--record(state, {total_memory,
-                allocated_memory}).
-
-%%----------------------------------------------------------------------------
-
--ifdef(use_specs).
-
--type(state() :: #state { total_memory :: ('undefined' | non_neg_integer()),
-                          allocated_memory :: ('undefined' | non_neg_integer())
-                        }).
-
--spec(init/0 :: () -> state()).
--spec(update/1 :: (state()) -> state()).
--spec(get_memory_data/1 :: (state()) -> {non_neg_integer(), non_neg_integer(),
-                                         ('undefined' | pid())}).
-
--endif.
-
-%%----------------------------------------------------------------------------
-
-init() -> 
-    #state{total_memory = undefined,
-           allocated_memory = undefined}.
-
-update(State) ->
-    File = read_proc_file("/proc/meminfo"),
-    Lines = string:tokens(File, "\n"),
-    Dict = dict:from_list(lists:map(fun parse_line/1, Lines)),
-    [MemTotal, MemFree, Buffers, Cached] =
-        [dict:fetch(Key, Dict) ||
-            Key <- ['MemTotal', 'MemFree', 'Buffers', 'Cached']],
-    MemUsed = MemTotal - MemFree - Buffers - Cached,
-    State#state{total_memory = MemTotal, allocated_memory = MemUsed}.
-
-get_memory_data(State) ->
-    {State#state.total_memory, State#state.allocated_memory, undefined}.
-
-%%----------------------------------------------------------------------------
-
--define(BUFFER_SIZE, 1024).
-
-%% file:read_file does not work on files in /proc as it seems to get
-%% the size of the file first and then read that many bytes. But files
-%% in /proc always have length 0, we just have to read until we get
-%% eof.
-read_proc_file(File) ->
-    {ok, IoDevice} = file:open(File, [read, raw]),
-    Res = read_proc_file(IoDevice, []),
-    file:close(IoDevice),
-    lists:flatten(lists:reverse(Res)).
-    
-read_proc_file(IoDevice, Acc) ->
-    case file:read(IoDevice, ?BUFFER_SIZE) of
-        {ok, Res} -> read_proc_file(IoDevice, [Res | Acc]);
-        eof       -> Acc
-    end.
-
-%% A line looks like "FooBar: 123456 kB"
-parse_line(Line) ->
-    [Name, RHS | _Rest] = string:tokens(Line, ":"),
-    [Value | UnitsRest] = string:tokens(RHS, " "),
-    Value1 = case UnitsRest of
-                 [] -> list_to_integer(Value); %% no units
-                 ["kB"] -> list_to_integer(Value) * 1024
-             end,
-    {list_to_atom(Name), Value1}.
diff --git a/src/vm_memory_monitor.erl b/src/vm_memory_monitor.erl
new file mode 100644
index 00000000..46c36af4
--- /dev/null
+++ b/src/vm_memory_monitor.erl
@@ -0,0 +1,307 @@
+%%   The contents of this file are subject to the Mozilla Public License
+%%   Version 1.1 (the "License"); you may not use this file except in
+%%   compliance with the License. You may obtain a copy of the License at
+%%   http://www.mozilla.org/MPL/
+%%
+%%   Software distributed under the License is distributed on an "AS IS"
+%%   basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the
+%%   License for the specific language governing rights and limitations
+%%   under the License.
+%%
+%%   The Original Code is RabbitMQ.
+%%
+%%   The Initial Developers of the Original Code are LShift Ltd,
+%%   Cohesive Financial Technologies LLC, and Rabbit Technologies Ltd.
+%%
+%%   Portions created before 22-Nov-2008 00:00:00 GMT by LShift Ltd,
+%%   Cohesive Financial Technologies LLC, or Rabbit Technologies Ltd
+%%   are Copyright (C) 2007-2008 LShift Ltd, Cohesive Financial
+%%   Technologies LLC, and Rabbit Technologies Ltd.
+%%
+%%   Portions created by LShift Ltd are Copyright (C) 2007-2009 LShift
+%%   Ltd. Portions created by Cohesive Financial Technologies LLC are
+%%   Copyright (C) 2007-2009 Cohesive Financial Technologies
+%%   LLC. Portions created by Rabbit Technologies Ltd are Copyright
+%%   (C) 2007-2009 Rabbit Technologies Ltd.
+%%
+%%   All Rights Reserved.
+%%
+%%   Contributor(s): ______________________________________.
+%%
+
+%% In practice Erlang shouldn't be allowed to grow to more than a half
+%% of available memory. The pessimistic scenario is when the Erlang VM
+%% has a single process that's consuming all memory. In such a case,
+%% during garbage collection, Erlang tries to allocate a huge chunk of
+%% continuous memory, which can result in a crash or heavy swapping.
+%% 
+%% This module tries to warn Rabbit before such situations occur, so
+%% that it has a higher chance to avoid running out of memory.
+%%
+%% This code depends on Erlang os_mon application.
+
+-module(vm_memory_monitor).
+
+-behaviour(gen_server2).
+
+-export([start_link/1]).
+
+-export([init/1, handle_call/3, handle_cast/2, handle_info/2,
+         terminate/2, code_change/3]).
+
+-export([update/0, get_total_memory/0,
+         get_check_interval/0, set_check_interval/1,
+         get_vm_memory_high_watermark/0, set_vm_memory_high_watermark/1]).
+
+
+-define(SERVER, ?MODULE).
+-define(DEFAULT_MEMORY_CHECK_INTERVAL, 1000).
+
+%% For an unknown OS, we assume that we have 1GB of memory. It'll be
+%% wrong. Scale by vm_memory_high_watermark in configuration to get a
+%% sensible value.
+-define(MEMORY_SIZE_FOR_UNKNOWN_OS, 1073741824).
+
+-record(state, {total_memory,
+                memory_limit,
+                timeout,
+                timer,
+                alarmed
+               }).
+
+%%----------------------------------------------------------------------------
+%% gen_server callbacks
+%%----------------------------------------------------------------------------
+
+start_link(Args) ->
+    gen_server2:start_link({local, ?SERVER}, ?MODULE, [Args], []).
+
+init([MemFraction]) -> 
+    TotalMemory =
+        case get_total_memory() of
+            unknown ->
+                rabbit_log:warning("Unknown total memory size for your OS ~p. "
+                                   "Assuming memory size is ~p bytes.~n", 
+                                   [os:type(), ?MEMORY_SIZE_FOR_UNKNOWN_OS]),
+                ?MEMORY_SIZE_FOR_UNKNOWN_OS;
+            M -> M
+        end,
+    MemLimit = get_mem_limit(MemFraction, TotalMemory),
+    rabbit_log:info("Memory limit set to ~pMB.~n", [trunc(MemLimit/1048576)]),
+    TRef = start_timer(?DEFAULT_MEMORY_CHECK_INTERVAL),
+    State = #state { total_memory = TotalMemory,
+                     memory_limit = MemLimit,
+                     timeout = ?DEFAULT_MEMORY_CHECK_INTERVAL,
+                     timer = TRef,
+                     alarmed = false},
+    {ok, internal_update(State)}.
+
+handle_call(get_vm_memory_high_watermark, _From, State) ->
+    {reply, State#state.memory_limit / State#state.total_memory, State};
+
+handle_call({set_vm_memory_high_watermark, MemFraction}, _From, State) ->
+    MemLimit = get_mem_limit(MemFraction, State#state.total_memory),
+    rabbit_log:info("Memory alarm changed to ~p, ~p bytes.~n", 
+                    [MemFraction, MemLimit]),
+    {reply, ok, State#state{memory_limit = MemLimit}};
+
+handle_call(get_check_interval, _From, State) ->
+    {reply, State#state.timeout, State};
+
+handle_call({set_check_interval, Timeout}, _From, State) ->
+    {ok, cancel} = timer:cancel(State#state.timer),
+    {reply, ok, State#state{timeout = Timeout, timer = start_timer(Timeout)}};
+
+handle_call(_Request, _From, State) ->
+    {noreply, State}.
+
+handle_cast(update, State) ->
+    {noreply, internal_update(State)};
+
+handle_cast(_Request, State) -> 
+    {noreply, State}.
+
+handle_info(_Info, State) -> 
+    {noreply, State}.
+
+terminate(_Reason, _State) -> 
+    ok.
+
+code_change(_OldVsn, State, _Extra) -> 
+    {ok, State}.
+
+%%----------------------------------------------------------------------------
+%% Public API
+%%----------------------------------------------------------------------------
+ 
+update() ->
+    gen_server2:cast(?SERVER, update).
+
+get_total_memory() ->
+    get_total_memory(os:type()).
+
+get_check_interval() ->
+    gen_server2:call(?MODULE, get_check_interval).
+
+set_check_interval(Fraction) ->
+    gen_server2:call(?MODULE, {set_check_interval, Fraction}).
+
+get_vm_memory_high_watermark() ->
+    gen_server2:call(?MODULE, get_vm_memory_high_watermark).
+
+set_vm_memory_high_watermark(Fraction) ->
+    gen_server2:call(?MODULE, {set_vm_memory_high_watermark, Fraction}).
+
+%%----------------------------------------------------------------------------
+%% Server Internals
+%%----------------------------------------------------------------------------
+
+internal_update(State = #state { memory_limit = MemLimit,
+                                 alarmed = Alarmed}) ->
+    MemUsed = erlang:memory(total),
+    NewAlarmed = MemUsed > MemLimit,
+    case {Alarmed, NewAlarmed} of
+        {false, true} ->
+            emit_update_info(set, MemUsed, MemLimit),
+            alarm_handler:set_alarm({vm_memory_high_watermark, []});
+        {true, false} ->
+            emit_update_info(clear, MemUsed, MemLimit),
+            alarm_handler:clear_alarm(vm_memory_high_watermark);
+        _ ->
+            ok
+    end,
+    State #state {alarmed = NewAlarmed}.
+
+emit_update_info(State, MemUsed, MemLimit) ->
+    rabbit_log:info("vm_memory_high_watermark ~p. Memory used:~p allowed:~p~n",
+                    [State, MemUsed, MemLimit]).
+
+start_timer(Timeout) ->
+    {ok, TRef} = timer:apply_interval(Timeout, ?MODULE, update, []),
+    TRef.
+
+%% On a 32-bit machine, if you're using more than 2 gigs of RAM you're
+%% in big trouble anyway.
+get_vm_limit() ->
+    case erlang:system_info(wordsize) of
+        4 -> 2147483648;     %% 2 GB for 32 bits  2^31
+        8 -> 140737488355328 %% 128 TB for 64 bits 2^47
+             %% http://en.wikipedia.org/wiki/X86-64#Virtual_address_space_details
+    end.
+
+get_mem_limit(MemFraction, TotalMemory) ->
+    lists:min([trunc(TotalMemory * MemFraction), get_vm_limit()]).
+
+%%----------------------------------------------------------------------------
+%% Internal Helpers
+%%----------------------------------------------------------------------------
+
+%% get_total_memory(OS) -> Total
+%% Windows and Freebsd code based on: memsup:get_memory_usage/1
+%% Original code was part of OTP and released under "Erlang Public
+%% License".
+
+%% Darwin: Uses vm_stat command.
+get_total_memory({unix,darwin}) ->
+    File = os:cmd("/usr/bin/vm_stat"),
+    Lines = string:tokens(File, "\n"),
+    Dict = dict:from_list(lists:map(fun parse_line_mach/1, Lines)),
+    [PageSize, Inactive, Active, Free, Wired] =
+        [dict:fetch(Key, Dict) ||
+            Key <- [page_size, 'Pages inactive', 'Pages active', 'Pages free',
+                    'Pages wired down']],
+    PageSize * (Inactive + Active + Free + Wired);
+
+%% FreeBSD: Look in /usr/include/sys/vmmeter.h for the format of
+%% struct vmmeter
+get_total_memory({unix,freebsd}) ->
+    PageSize  = freebsd_sysctl("vm.stats.vm.v_page_size"),
+    PageCount = freebsd_sysctl("vm.stats.vm.v_page_count"),
+    PageCount * PageSize;
+
+%% Win32: Find out how much memory is in use by asking the
+%% os_mon_sysinfo process.
+get_total_memory({win32,_OSname}) ->
+    [Result|_] = os_mon_sysinfo:get_mem_info(),
+    {ok, [_MemLoad, TotPhys, _AvailPhys,
+          _TotPage, _AvailPage, _TotV, _AvailV], _RestStr} =
+        io_lib:fread("~d~d~d~d~d~d~d", Result),
+    TotPhys;
+
+%% Linux: Look in /proc/meminfo
+get_total_memory({unix, linux}) ->
+    File = read_proc_file("/proc/meminfo"),
+    Lines = string:tokens(File, "\n"),
+    Dict = dict:from_list(lists:map(fun parse_line_linux/1, Lines)),
+    dict:fetch('MemTotal', Dict);
+
+get_total_memory({unix, sunos}) ->
+    File = os:cmd("/usr/sbin/prtconf"),
+    Lines = string:tokens(File, "\n"),
+    Dict = dict:from_list(lists:map(fun parse_line_sunos/1, Lines)),
+    dict:fetch('Memory size', Dict);
+
+get_total_memory(_OsType) ->
+    unknown.
+
+%% A line looks like "Foo bar: 123456."
+parse_line_mach(Line) ->
+    [Name, RHS | _Rest] = string:tokens(Line, ":"),
+    case Name of
+        "Mach Virtual Memory Statistics" ->
+            ["(page", "size", "of", PageSize, "bytes)"] =
+                string:tokens(RHS, " "),
+            {page_size, list_to_integer(PageSize)};
+        _ ->
+            [Value | _Rest1] = string:tokens(RHS, " ."),
+            {list_to_atom(Name), list_to_integer(Value)}
+    end.
+
+%% A line looks like "FooBar: 123456 kB"
+parse_line_linux(Line) ->
+    [Name, RHS | _Rest] = string:tokens(Line, ":"),
+    [Value | UnitsRest] = string:tokens(RHS, " "),
+    Value1 = case UnitsRest of
+                 [] -> list_to_integer(Value); %% no units
+                 ["kB"] -> list_to_integer(Value) * 1024
+             end,
+    {list_to_atom(Name), Value1}.
+
+%% A line looks like "Memory size: 1024 Megabytes"
+parse_line_sunos(Line) ->
+    case string:tokens(Line, ":") of
+        [Name, RHS | _Rest] ->
+            [Value1 | UnitsRest] = string:tokens(RHS, " "),
+            Value2 = case UnitsRest of
+                         ["Gigabytes"] ->
+                             list_to_integer(Value1) * 1024 * 1024 * 1024;
+                         ["Megabytes"] ->
+                             list_to_integer(Value1) * 1024 * 1024;
+                         ["Kilobytes"] ->
+                             list_to_integer(Value1) * 1024;
+                         _ ->
+                             Value1 ++ UnitsRest %% no known units
+                     end,
+            {list_to_atom(Name), Value2};
+        [Name] -> {list_to_atom(Name), none}
+    end.
+
+freebsd_sysctl(Def) ->
+    list_to_integer(os:cmd("/sbin/sysctl -n " ++ Def) -- "\n").
+
+%% file:read_file does not work on files in /proc as it seems to get
+%% the size of the file first and then read that many bytes. But files
+%% in /proc always have length 0, we just have to read until we get
+%% eof.
+read_proc_file(File) ->
+    {ok, IoDevice} = file:open(File, [read, raw]),
+    Res = read_proc_file(IoDevice, []),
+    file:close(IoDevice),
+    lists:flatten(lists:reverse(Res)).
+
+-define(BUFFER_SIZE, 1024).
+read_proc_file(IoDevice, Acc) ->
+    case file:read(IoDevice, ?BUFFER_SIZE) of
+        {ok, Res} -> read_proc_file(IoDevice, [Res | Acc]);
+        eof       -> Acc
+    end.