From 7ff352ef8a5393a017ce493ba1a1fc3be54be245 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jos=C3=A9=20Valim?= Date: Wed, 10 May 2017 14:20:13 +0200 Subject: Do not discard stacktraces on gen_server exits Prior to this patch, the stacktrace of an error or exit in a callback would always be discarded in crash reports. For example, an exit(crashed) in handle_call/3 would emit: =CRASH REPORT==== 10-May-2017::14:15:50 === crasher: initial call: gen_server_SUITE:init/1 pid: <0.201.0> registered_name: [] exception exit: crashed in function gen_server:terminate/8 (src/gen_server.erl, line 828) Note that the stacktrace is pointing to the gen_server internal terminate implementation that calls exit/1. This patch uses erlang:raise/3 so the stacktrace is not lost, allowing proc_lib to show the class, reason and stacktrace coming from the user implementation (in this case gen_server_SUITE): =CRASH REPORT==== 10-May-2017::14:16:44 === crasher: initial call: gen_server_SUITE:init/1 pid: <0.197.0> registered_name: [] exception exit: crashed in function gen_server_SUITE:handle_call/3 (gen_server_SUITE.erl, line 1529) This change is completely backwards compatible as using erlang:raise/3 will still emit the same exit reason to any linked process and monitor as before. --- lib/stdlib/src/gen_server.erl | 174 +++++++++++++++++++---------------- lib/stdlib/test/gen_server_SUITE.erl | 2 +- 2 files changed, 97 insertions(+), 79 deletions(-) diff --git a/lib/stdlib/src/gen_server.erl b/lib/stdlib/src/gen_server.erl index ba0a7ae8e5..4e9dea8e5a 100644 --- a/lib/stdlib/src/gen_server.erl +++ b/lib/stdlib/src/gen_server.erl @@ -109,6 +109,10 @@ -import(error_logger, [format/2]). +-define( + STACKTRACE(), + try throw(ok) catch _ -> erlang:get_stacktrace() end). + %%%========================================================================= %%% API %%%========================================================================= @@ -326,15 +330,16 @@ 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), - HibernateAfterTimeout = gen:hibernate_after(Options), - case catch Mod:init(Args) of - {ok, State} -> + HibernateAfterTimeout = gen:hibernate_after(Options), + + case init_it(Mod, Args) of + {ok, {ok, State}} -> proc_lib:init_ack(Starter, {ok, self()}), loop(Parent, Name, State, Mod, infinity, HibernateAfterTimeout, Debug); - {ok, State, Timeout} -> + {ok, {ok, State, Timeout}} -> proc_lib:init_ack(Starter, {ok, self()}), loop(Parent, Name, State, Mod, Timeout, HibernateAfterTimeout, Debug); - {stop, Reason} -> + {ok, {stop, Reason}} -> %% For consistency, we must make sure that the %% registered name (if any) is unregistered before %% the parent process is notified about the failure. @@ -344,18 +349,25 @@ init_it(Starter, Parent, Name0, Mod, Args, Options) -> gen:unregister_name(Name0), proc_lib:init_ack(Starter, {error, Reason}), exit(Reason); - ignore -> + {ok, ignore} -> gen:unregister_name(Name0), proc_lib:init_ack(Starter, ignore), exit(normal); - {'EXIT', Reason} -> - gen:unregister_name(Name0), - proc_lib:init_ack(Starter, {error, Reason}), - exit(Reason); - Else -> + {ok, Else} -> Error = {bad_return_value, Else}, proc_lib:init_ack(Starter, {error, Error}), - exit(Error) + exit(Error); + {'EXIT', Class, Reason, Stacktrace} -> + gen:unregister_name(Name0), + proc_lib:init_ack(Starter, {error, terminate_reason(Class, Reason, Stacktrace)}), + erlang:raise(Class, Reason, Stacktrace) + end. +init_it(Mod, Args) -> + try + {ok, Mod:init(Args)} + catch + throw:R -> {ok, R}; + Class:R -> {'EXIT', Class, R, erlang:get_stacktrace()} end. %%%======================================================================== @@ -397,7 +409,7 @@ decode_msg(Msg, Parent, Name, State, Mod, Time, HibernateAfterTimeout, Debug, Hi sys:handle_system_msg(Req, From, Parent, ?MODULE, Debug, [Name, State, Mod, Time, HibernateAfterTimeout], Hib); {'EXIT', Parent, Reason} -> - terminate(Reason, Name, undefined, Msg, Mod, State, Debug); + terminate(Reason, ?STACKTRACE(), Name, undefined, Msg, Mod, State, Debug); _Msg when Debug =:= [] -> handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout); _Msg -> @@ -589,17 +601,11 @@ start_monitor(Node, Name) when is_atom(Node), is_atom(Name) -> %% --------------------------------------------------- %% Helper functions for try-catch of callbacks. %% Returns the return value of the callback, or -%% {'EXIT', ExitReason, ReportReason} (if an exception occurs) +%% {'EXIT', Class, Reason, Stack} (if an exception occurs) %% -%% ExitReason is the reason that shall be used when the process -%% terminates. -%% -%% ReportReason is the reason that shall be printed in the error -%% report. -%% -%% These functions are introduced in order to add the stack trace in -%% the error report produced when a callback is terminated with -%% erlang:exit/1 (OTP-12263). +%% The Class, Reason and Stack are given to erlang:raise/3 +%% to make sure proc_lib receives the proper reasons and +%% stacktraces. %% --------------------------------------------------- try_dispatch({'$gen_cast', Msg}, Mod, State) -> @@ -621,15 +627,10 @@ try_dispatch(Mod, Func, Msg, State) -> [Mod, Msg]), {ok, {noreply, State}}; true -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', {R, Stacktrace}, {R, Stacktrace}} + {'EXIT', error, R, erlang:get_stacktrace()} end; - error:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', {R, Stacktrace}, {R, Stacktrace}}; - exit:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', R, {R, Stacktrace}} + Class:R -> + {'EXIT', Class, R, erlang:get_stacktrace()} end. try_handle_call(Mod, Msg, From, State) -> @@ -638,12 +639,8 @@ try_handle_call(Mod, Msg, From, State) -> catch throw:R -> {ok, R}; - error:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', {R, Stacktrace}, {R, Stacktrace}}; - exit:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', R, {R, Stacktrace}} + Class:R -> + {'EXIT', Class, R, erlang:get_stacktrace()} end. try_terminate(Mod, Reason, State) -> @@ -654,12 +651,8 @@ try_terminate(Mod, Reason, State) -> catch throw:R -> {ok, R}; - error:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', {R, Stacktrace}, {R, Stacktrace}}; - exit:R -> - Stacktrace = erlang:get_stacktrace(), - {'EXIT', R, {R, Stacktrace}} + Class:R -> + {'EXIT', Class, R, erlang:get_stacktrace()} end; false -> {ok, ok} @@ -684,10 +677,11 @@ handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, HibernateAfterTim {ok, {noreply, NState, Time1}} -> loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, []); {ok, {stop, Reason, Reply, NState}} -> - {'EXIT', R} = - (catch terminate(Reason, Name, From, Msg, Mod, NState, [])), - reply(From, Reply), - exit(R); + try + terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, []) + after + reply(From, Reply) + end; Other -> handle_common_reply(Other, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State) end; handle_msg(Msg, Parent, Name, State, Mod, HibernateAfterTimeout) -> @@ -712,10 +706,11 @@ handle_msg({'$gen_call', From, Msg}, Parent, Name, State, Mod, HibernateAfterTim {noreply, NState}), loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, 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); + try + terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, Debug) + after + _ = reply(Name, From, Reply, NState, Debug) + end; Other -> handle_common_reply(Other, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State, Debug) end; @@ -730,11 +725,11 @@ handle_common_reply(Reply, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, {ok, {noreply, NState, Time1}} -> loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, []); {ok, {stop, Reason, NState}} -> - terminate(Reason, Name, From, Msg, Mod, NState, []); - {'EXIT', ExitReason, ReportReason} -> - terminate(ExitReason, ReportReason, Name, From, Msg, Mod, State, []); + terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, []); + {'EXIT', Class, Reason, Stacktrace} -> + terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, []); {ok, BadReply} -> - terminate({bad_return_value, BadReply}, Name, From, Msg, Mod, State, []) + terminate({bad_return_value, BadReply}, ?STACKTRACE(), Name, From, Msg, Mod, State, []) end. handle_common_reply(Reply, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, State, Debug) -> @@ -748,11 +743,11 @@ handle_common_reply(Reply, Parent, Name, From, Msg, Mod, HibernateAfterTimeout, {noreply, NState}), loop(Parent, Name, NState, Mod, Time1, HibernateAfterTimeout, Debug1); {ok, {stop, Reason, NState}} -> - terminate(Reason, Name, From, Msg, Mod, NState, Debug); - {'EXIT', ExitReason, ReportReason} -> - terminate(ExitReason, ReportReason, Name, From, Msg, Mod, State, Debug); + terminate(Reason, ?STACKTRACE(), Name, From, Msg, Mod, NState, Debug); + {'EXIT', Class, Reason, Stacktrace} -> + terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, Debug); {ok, BadReply} -> - terminate({bad_return_value, BadReply}, Name, From, Msg, Mod, State, Debug) + terminate({bad_return_value, BadReply}, ?STACKTRACE(), Name, From, Msg, Mod, State, Debug) end. reply(Name, {To, Tag}, Reply, State, Debug) -> @@ -770,7 +765,7 @@ system_continue(Parent, Debug, [Name, State, Mod, Time, HibernateAfterTimeout]) -spec system_terminate(_, _, _, [_]) -> no_return(). system_terminate(Reason, _Parent, Debug, [Name, State, Mod, _Time, _HibernateAfterTimeout]) -> - terminate(Reason, Name, undefined, [], Mod, State, Debug). + terminate(Reason, ?STACKTRACE(), Name, undefined, [], Mod, State, Debug). system_code_change([Name, State, Mod, Time, HibernateAfterTimeout], _Module, OldVsn, Extra) -> case catch Mod:code_change(OldVsn, State, Extra) of @@ -811,35 +806,58 @@ print_event(Dev, Event, Name) -> %%% --------------------------------------------------- %%% Terminate the server. +%%% +%%% terminate/8 is triggered by {stop, Reason} or bad +%%% return values. The stacktrace is generated via the +%%% ?STACKTRACE() macro and the ReportReason must not +%%% be wrapped in tuples. +%%% +%%% terminate/9 is triggered in case of error/exit in +%%% the user callback. In this case the report reason +%%% always includes the user stacktrace. +%%% +%%% The reason received in the terminate/2 callbacks +%%% always includes the stacktrace for errors and never +%%% for exits. %%% --------------------------------------------------- - --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), +terminate(Reason, Stacktrace, Name, From, Msg, Mod, State, Debug) -> + terminate(exit, Reason, Stacktrace, Reason, Name, From, Msg, Mod, State, Debug). + +-spec terminate(_, _, _, _, _, _, _, _, _) -> no_return(). +terminate(Class, Reason, Stacktrace, Name, From, Msg, Mod, State, Debug) -> + ReportReason = {Reason, Stacktrace}, + terminate(Class, Reason, Stacktrace, ReportReason, Name, From, Msg, Mod, State, Debug). + +-spec terminate(_, _, _, _, _, _, _, _, _, _) -> no_return(). +terminate(Class, Reason, Stacktrace, ReportReason, Name, From, Msg, Mod, State, Debug) -> + Reply = try_terminate(Mod, terminate_reason(Class, Reason, Stacktrace), State), case Reply of - {'EXIT', ExitReason1, ReportReason1} -> + {'EXIT', C, R, S} -> FmtState = format_status(terminate, Mod, get(), State), - error_info(ReportReason1, Name, From, Msg, FmtState, Debug), - exit(ExitReason1); + error_info({R, S}, Name, From, Msg, FmtState, Debug), + erlang:raise(C, R, S); _ -> - case ExitReason of - normal -> - exit(normal); - shutdown -> - exit(shutdown); - {shutdown,_}=Shutdown -> - exit(Shutdown); + case {Class, Reason} of + {exit, normal} -> ok; + {exit, shutdown} -> ok; + {exit, {shutdown,_}} -> ok; _ -> FmtState = format_status(terminate, Mod, get(), State), - error_info(ReportReason, Name, From, Msg, FmtState, Debug), - exit(ExitReason) + error_info(ReportReason, Name, From, Msg, FmtState, Debug) end + end, + case Stacktrace of + [] -> + erlang:Class(Reason); + _ -> + erlang:raise(Class, Reason, Stacktrace) end. +terminate_reason(error, Reason, Stacktrace) -> {Reason, Stacktrace}; +terminate_reason(exit, Reason, _Stacktrace) -> Reason. + error_info(_Reason, application_controller, _From, _Msg, _State, _Debug) -> %% OTP-5811 Don't send an error report if it's the system process %% application_controller which is terminating - let init take care diff --git a/lib/stdlib/test/gen_server_SUITE.erl b/lib/stdlib/test/gen_server_SUITE.erl index 7e3c71715e..2e9dc4d4fb 100644 --- a/lib/stdlib/test/gen_server_SUITE.erl +++ b/lib/stdlib/test/gen_server_SUITE.erl @@ -404,7 +404,7 @@ crash(Config) when is_list(Config) -> end, receive {error_report,_,{Pid4,crash_report,[List4|_]}} -> - {exit,crashed,_} = proplists:get_value(error_info, List4), + {exit,crashed,[{?MODULE, handle_call, 3, _}|_]} = proplists:get_value(error_info, List4), Pid4 = proplists:get_value(pid, List4); Other4 -> io:format("Unexpected: ~p", [Other4]), -- cgit v1.2.3