From c15440cd74b04ba88f9af0a59f9505478d314d38 Mon Sep 17 00:00:00 2001 From: "Paul J. Davis" Date: Mon, 19 Dec 2011 13:39:49 -0600 Subject: Avoid scanning the entire table of procs For large numbers of os processes its possible that we have a slowdown when requesting a new process. The old code matches all possible processes out of the table to find an appropriate candidate. We avoid the issue by using ets:select_reverse to also prefer keeping newer processes and releasing longer lived processes. Length of life is based on the implicit sorting of pids having newer pids sorting larger. --- apps/couch/src/couch_proc_manager.erl | 87 ++++++++++++++++++++++++++--------- 1 file changed, 64 insertions(+), 23 deletions(-) (limited to 'apps/couch') diff --git a/apps/couch/src/couch_proc_manager.erl b/apps/couch/src/couch_proc_manager.erl index 6c2d339f..d3072c71 100644 --- a/apps/couch/src/couch_proc_manager.erl +++ b/apps/couch/src/couch_proc_manager.erl @@ -17,7 +17,7 @@ get_proc_count() -> init([]) -> process_flag(trap_exit, true), - {ok, #state{tab = ets:new(procs, [{keypos, #proc.pid}])}}. + {ok, #state{tab = ets:new(procs, [ordered_set, {keypos, #proc.pid}])}}. handle_call(get_table, _From, State) -> {reply, State#state.tab, State}; @@ -27,33 +27,52 @@ handle_call(get_proc_count, _From, State) -> handle_call({get_proc, #doc{body={Props}}=DDoc, DDocKey}, From, State) -> Lang = couch_util:get_value(<<"language">>, Props, <<"javascript">>), - try get_procs(State#state.tab, Lang) of - [] -> - spawn_link(?MODULE, new_proc, [From, Lang, DDoc, DDocKey]), - {noreply, State}; - Procs -> - case proc_with_ddoc(DDoc, DDocKey, Procs) of - {ok, Proc0} -> - Client = element(1, From), - Proc = Proc0#proc{client = erlang:monitor(process, Client)}, - ets:insert(State#state.tab, Proc), - {reply, {ok, Proc, get_query_server_config()}, State}; - {error, Reason} -> - {reply, {error, Reason}, State} + IterFun = fun(Proc0, Acc) -> + case lists:member(DDocKey, Proc0#proc.ddoc_keys) of + true -> + {Client, _} = From, + Proc = Proc0#proc{client = erlang:monitor(process, Client)}, + ets:insert(State#state.tab, Proc), + {stop, Proc}; + false -> + {ok, Acc} end + end, + TeachFun = fun(Proc0, Acc) -> + try + {ok, Proc} = teach_ddoc(DDoc, DDocKey, Proc0), + {stop, Proc} + catch _:_ -> + {ok, Acc} + end + end, + try iter_procs(State#state.tab, Lang, IterFun, nil) of + {not_found, _} -> + case iter_procs(State#state.tab, Lang, TeachFun, nil) of + {not_found, _} -> + spawn_link(?MODULE, new_proc, [From, Lang, DDoc, DDocKey]), + {noreply, State}; + {ok, Proc} -> + {reply, {ok, Proc, get_query_server_config()}, State} + end; + {ok, Proc} -> + {reply, {ok, Proc, get_query_server_config()}, State} catch error:Reason -> ?LOG_ERROR("~p ~p ~p", [?MODULE, Reason, erlang:get_stacktrace()]), {reply, {error, Reason}, State} end; handle_call({get_proc, Lang}, {Client, _} = From, State) -> - try get_procs(State#state.tab, Lang) of - [] -> - spawn_link(?MODULE, new_proc, [From, Lang]), - {noreply, State}; - [Proc0|_] -> + IterFun = fun(Proc0, _Acc) -> Proc = Proc0#proc{client = erlang:monitor(process, Client)}, ets:insert(State#state.tab, Proc), + {stop, Proc} + end, + try iter_procs(State#state.tab, Lang, IterFun, nil) of + {not_found, _} -> + spawn_link(?MODULE, new_proc, [From, Lang]), + {noreply, State}; + {ok, Proc} -> {reply, {ok, Proc, get_query_server_config()}, State} catch error:Reason -> ?LOG_ERROR("~p ~p ~p", [?MODULE, Reason, erlang:get_stacktrace()]), @@ -128,10 +147,32 @@ code_change(_OldVsn, State, _Extra) -> {ok, State}. -get_procs(Tab, Lang) when is_binary(Lang) -> - get_procs(Tab, binary_to_list(Lang)); -get_procs(Tab, Lang) when is_list(Lang) -> - ets:match_object(Tab, #proc{lang=Lang, client=nil, _='_'}). + +iter_procs(Tab, Lang, Fun, Acc) when is_list(Lang) -> + iter_procs(Tab, list_to_binary(Lang), Fun, Acc); +iter_procs(Tab, Lang, Fun, Acc) -> + Pattern = #proc{lang=Lang, client=nil, _='_'}, + case ets:select_reverse(Tab, Pattern, 25) of + '$end_of_table' -> + {not_found, Acc}; + Continuation -> + iter_procs(Continuation, Fun, Acc) + end. + +iter_procs({[], Continuation0}, Fun, Acc) -> + case ets:select_reverse(Continuation0) of + '$end_of_table' -> + {not_found, Acc}; + Continuation1 -> + iter_procs(Continuation1, Fun, Acc) + end; +iter_procs({[Proc | Rest], Continuation}, Fun, Acc0) -> + case Fun(Proc, Acc0) of + {ok, Acc1} -> + iter_procs({Rest, Continuation}, Fun, Acc1); + {stop, Acc1} -> + {ok, Acc1} + end. new_proc(From, Lang) -> case new_proc_int(From, Lang) of -- cgit v1.2.3