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Diffstat (limited to 'src/vm_memory_monitor.erl')
| -rw-r--r-- | src/vm_memory_monitor.erl | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/src/vm_memory_monitor.erl b/src/vm_memory_monitor.erl new file mode 100644 index 00000000..8be28f52 --- /dev/null +++ b/src/vm_memory_monitor.erl @@ -0,0 +1,325 @@ +%% 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_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, 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 + }). + +%%---------------------------------------------------------------------------- + +-ifdef(use_specs). + +-spec(start_link/1 :: (float()) -> + ('ignore' | {'error', any()} | {'ok', pid()})). +-spec(update/0 :: () -> 'ok'). +-spec(get_total_memory/0 :: () -> (non_neg_integer() | 'unknown')). +-spec(get_check_interval/0 :: () -> non_neg_integer()). +-spec(set_check_interval/1 :: (non_neg_integer()) -> 'ok'). +-spec(get_vm_memory_high_watermark/0 :: () -> float()). +-spec(set_vm_memory_high_watermark/1 :: (float()) -> 'ok'). + +-endif. + + +%%---------------------------------------------------------------------------- +%% Public API +%%---------------------------------------------------------------------------- + +update() -> + gen_server:cast(?SERVER, update). + +get_total_memory() -> + get_total_memory(os:type()). + +get_check_interval() -> + gen_server:call(?MODULE, get_check_interval). + +set_check_interval(Fraction) -> + gen_server:call(?MODULE, {set_check_interval, Fraction}). + +get_vm_memory_high_watermark() -> + gen_server:call(?MODULE, get_vm_memory_high_watermark). + +set_vm_memory_high_watermark(Fraction) -> + gen_server:call(?MODULE, {set_vm_memory_high_watermark, Fraction}). + +%%---------------------------------------------------------------------------- +%% gen_server callbacks +%%---------------------------------------------------------------------------- + +start_link(Args) -> + gen_server:start_link({local, ?SERVER}, ?MODULE, [Args], []). + +init([MemFraction]) -> + TotalMemory = + case get_total_memory() of + unknown -> + error_logger:warning_msg( + "Unknown total memory size for your OS ~p. " + "Assuming memory size is ~pMB.~n", + [os:type(), trunc(?MEMORY_SIZE_FOR_UNKNOWN_OS/1048576)]), + ?MEMORY_SIZE_FOR_UNKNOWN_OS; + M -> M + end, + MemLimit = get_mem_limit(MemFraction, TotalMemory), + error_logger:info_msg("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), + error_logger:info_msg("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}. + +%%---------------------------------------------------------------------------- +%% 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) -> + error_logger:info_msg( + "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 -> 4294967296; %% 4 GB for 32 bits 2^32 + 8 -> 281474976710656 %% 256 TB for 64 bits 2^48 + %%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 +%%---------------------------------------------------------------------------- +cmd(Command) -> + Exec = hd(string:tokens(Command, " ")), + case os:find_executable(Exec) of + false -> throw({command_not_found, Exec}); + _ -> os:cmd(Command) + end. + +%% 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". + +get_total_memory({unix,darwin}) -> + File = 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); + +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; + +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; + +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 = 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(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. |