%%%-------------------------------------------------------------------
%%% File : ejabberd_system_monitor.erl
%%% Author : Alexey Shchepin <alexey@process-one.net>
%%% Description : ejabberd watchdog
%%% Created : 21 Mar 2007 by Alexey Shchepin <alexey@process-one.net>
%%%
%%%
%%% ejabberd, Copyright (C) 2002-2022 ProcessOne
%%%
%%% This program is free software; you can redistribute it and/or
%%% modify it under the terms of the GNU General Public License as
%%% published by the Free Software Foundation; either version 2 of the
%%% License, or (at your option) any later version.
%%%
%%% This program is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
%%% General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License along
%%% with this program; if not, write to the Free Software Foundation, Inc.,
%%% 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
%%%
%%%-------------------------------------------------------------------
-module(ejabberd_system_monitor).
-behaviour(gen_event).
-author('alexey@process-one.net').
-author('ekhramtsov@process-one.net').
%% API
-export([start/0, config_reloaded/0]).
%% gen_event callbacks
-export([init/1, handle_event/2, handle_call/2,
handle_info/2, terminate/2, code_change/3]).
-include("logger.hrl").
-define(CHECK_INTERVAL, timer:seconds(30)).
-record(state, {tref :: undefined | reference(),
mref :: undefined | reference()}).
-record(proc_stat, {qlen :: non_neg_integer(),
memory :: non_neg_integer(),
initial_call :: mfa(),
current_function :: mfa(),
ancestors :: [pid() | atom()],
application :: pid() | atom(),
name :: pid() | atom()}).
-type state() :: #state{}.
-type proc_stat() :: #proc_stat{}.
-type app_pids() :: #{pid() => atom()}.
%%%===================================================================
%%% API
%%%===================================================================
-spec start() -> ok.
start() ->
gen_event:add_handler(alarm_handler, ?MODULE, []),
gen_event:swap_handler(alarm_handler, {alarm_handler, swap}, {?MODULE, []}),
application:load(os_mon),
application:set_env(os_mon, start_cpu_sup, false),
application:set_env(os_mon, start_os_sup, false),
application:set_env(os_mon, start_memsup, true),
application:set_env(os_mon, start_disksup, false),
ejabberd:start_app(os_mon),
set_oom_watermark().
excluded_apps() ->
[os_mon, mnesia, sasl, stdlib, kernel].
-spec config_reloaded() -> ok.
config_reloaded() ->
set_oom_watermark().
%%%===================================================================
%%% gen_event callbacks
%%%===================================================================
init([]) ->
ejabberd_hooks:add(config_reloaded, ?MODULE, config_reloaded, 50),
{ok, #state{}}.
handle_event({set_alarm, {system_memory_high_watermark, _}}, State) ->
handle_overload(State),
{ok, restart_timer(State)};
handle_event({clear_alarm, system_memory_high_watermark}, State) ->
misc:cancel_timer(State#state.tref),
{ok, State#state{tref = undefined}};
handle_event({set_alarm, {process_memory_high_watermark, Pid}}, State) ->
case proc_stat(Pid, get_app_pids()) of
#proc_stat{name = Name} = ProcStat ->
?WARNING_MSG(
"Process ~p consumes more than 5% of OS memory (~ts)~n",
[Name, format_proc(ProcStat)]),
handle_overload(State),
{ok, State};
_ ->
{ok, State}
end;
handle_event({clear_alarm, process_memory_high_watermark}, State) ->
{ok, State};
handle_event(Event, State) ->
?WARNING_MSG("unexpected event: ~p~n", [Event]),
{ok, State}.
handle_call(_Request, State) ->
{ok, {error, badarg}, State}.
handle_info({timeout, _TRef, handle_overload}, State) ->
handle_overload(State),
{ok, restart_timer(State)};
handle_info(Info, State) ->
?WARNING_MSG("unexpected info: ~p~n", [Info]),
{ok, State}.
terminate(_Reason, _State) ->
ejabberd_hooks:delete(config_reloaded, ?MODULE, config_reloaded, 50).
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
%%%===================================================================
%%% Internal functions
%%%===================================================================
-spec handle_overload(state()) -> ok.
handle_overload(State) ->
handle_overload(State, processes()).
-spec handle_overload(state(), [pid()]) -> ok.
handle_overload(_State, Procs) ->
AppPids = get_app_pids(),
{TotalMsgs, ProcsNum, Apps, Stats} = overloaded_procs(AppPids, Procs),
MaxMsgs = ejabberd_option:oom_queue(),
if TotalMsgs >= MaxMsgs ->
SortedStats = lists:reverse(lists:keysort(#proc_stat.qlen, Stats)),
?WARNING_MSG(
"The system is overloaded with ~b messages "
"queued by ~b process(es) (~b%) "
"from the following applications: ~ts; "
"the top processes are:~n~ts~n",
[TotalMsgs, ProcsNum,
round(ProcsNum*100/length(Procs)),
format_apps(Apps),
format_top_procs(SortedStats)]),
kill(SortedStats, round(TotalMsgs/ProcsNum));
true ->
ok
end,
lists:foreach(fun erlang:garbage_collect/1, Procs).
-spec get_app_pids() -> app_pids().
get_app_pids() ->
try application:info() of
Info ->
case lists:keyfind(running, 1, Info) of
{_, Apps} ->
lists:foldl(
fun({Name, Pid}, M) when is_pid(Pid) ->
maps:put(Pid, Name, M);
(_, M) ->
M
end, #{}, Apps);
false ->
#{}
end
catch _:_ ->
#{}
end.
-spec overloaded_procs(app_pids(), [pid()])
-> {non_neg_integer(), non_neg_integer(), dict:dict(), [proc_stat()]}.
overloaded_procs(AppPids, AllProcs) ->
lists:foldl(
fun(Pid, {TotalMsgs, ProcsNum, Apps, Stats}) ->
case proc_stat(Pid, AppPids) of
#proc_stat{qlen = QLen, application = App} = Stat
when QLen > 0 ->
{TotalMsgs + QLen, ProcsNum + 1,
dict:update_counter(App, QLen, Apps),
[Stat|Stats]};
_ ->
{TotalMsgs, ProcsNum, Apps, Stats}
end
end, {0, 0, dict:new(), []}, AllProcs).
-spec proc_stat(pid(), app_pids()) -> proc_stat() | undefined.
proc_stat(Pid, AppPids) ->
case process_info(Pid, [message_queue_len,
memory,
initial_call,
current_function,
dictionary,
group_leader,
registered_name]) of
[{_, MsgLen}, {_, Mem}, {_, InitCall},
{_, CurrFun}, {_, Dict}, {_, GL}, {_, Name}] ->
IntLen = proplists:get_value('$internal_queue_len', Dict, 0),
TrueInitCall = proplists:get_value('$initial_call', Dict, InitCall),
Ancestors = proplists:get_value('$ancestors', Dict, []),
Len = IntLen + MsgLen,
App = maps:get(GL, AppPids, kernel),
RegName = case Name of
[] -> Pid;
_ -> Name
end,
#proc_stat{qlen = Len,
memory = Mem,
initial_call = TrueInitCall,
current_function = CurrFun,
ancestors = Ancestors,
application = App,
name = RegName};
_ ->
undefined
end.
-spec restart_timer(#state{}) -> #state{}.
restart_timer(State) ->
misc:cancel_timer(State#state.tref),
TRef = erlang:start_timer(?CHECK_INTERVAL, self(), handle_overload),
State#state{tref = TRef}.
-spec format_apps(dict:dict()) -> iodata().
format_apps(Apps) ->
AppList = lists:reverse(lists:keysort(2, dict:to_list(Apps))),
string:join(
[io_lib:format("~p (~b msgs)", [App, Msgs]) || {App, Msgs} <- AppList],
", ").
-spec format_top_procs([proc_stat()]) -> iodata().
format_top_procs(Stats) ->
Stats1 = lists:sublist(Stats, 5),
string:join(
lists:map(
fun(#proc_stat{name = Name} = Stat) ->
[io_lib:format("** ~w: ", [Name]), format_proc(Stat)]
end,Stats1),
io_lib:nl()).
-spec format_proc(proc_stat()) -> iodata().
format_proc(#proc_stat{qlen = Len, memory = Mem, initial_call = InitCall,
current_function = CurrFun, ancestors = Ancs,
application = App}) ->
io_lib:format(
"msgs = ~b, memory = ~b, initial_call = ~ts, "
"current_function = ~ts, ancestors = ~w, application = ~w",
[Len, Mem, format_mfa(InitCall), format_mfa(CurrFun), Ancs, App]).
-spec format_mfa(mfa()) -> iodata().
format_mfa({M, F, A}) when is_atom(M), is_atom(F), is_integer(A) ->
io_lib:format("~ts:~ts/~b", [M, F, A]);
format_mfa(WTF) ->
io_lib:format("~w", [WTF]).
-spec kill([proc_stat()], non_neg_integer()) -> ok.
kill(Stats, Threshold) ->
case ejabberd_option:oom_killer() of
true ->
do_kill(Stats, Threshold);
false ->
ok
end.
-spec do_kill([proc_stat()], non_neg_integer()) -> ok.
do_kill(Stats, Threshold) ->
Killed = lists:filtermap(
fun(#proc_stat{qlen = Len, name = Name, application = App})
when Len >= Threshold ->
case lists:member(App, excluded_apps()) of
true ->
?WARNING_MSG(
"Unable to kill process ~p from whitelisted "
"application ~p~n", [Name, App]),
false;
false ->
case kill_proc(Name) of
false ->
false;
Pid ->
{true, Pid}
end
end;
(_) ->
false
end, Stats),
TotalKilled = length(Killed),
if TotalKilled > 0 ->
?ERROR_MSG(
"Killed ~b process(es) consuming more than ~b message(s) each~n",
[TotalKilled, Threshold]);
true ->
ok
end.
-spec kill_proc(pid() | atom()) -> false | pid().
kill_proc(undefined) ->
false;
kill_proc(Name) when is_atom(Name) ->
kill_proc(whereis(Name));
kill_proc(Pid) ->
exit(Pid, kill),
Pid.
-spec set_oom_watermark() -> ok.
set_oom_watermark() ->
WaterMark = ejabberd_option:oom_watermark(),
memsup:set_sysmem_high_watermark(WaterMark/100).
