From 6fba00f0e0e66311dd3a476aaa0c9d7f288a2a9b Mon Sep 17 00:00:00 2001 From: Dan Gudmundsson Date: Thu, 11 Oct 2012 14:52:21 +0200 Subject: stdlib: Monitor proc_lib:start'ed processes to avoid waiting forever Monitor the spawned process in proc_lib:start/[3|4|5], so that a proper error is returned, if the spawned process crashes before proclib:init_ack/1 is sent. Previously the calling process would hang forever or until specified timeout. Start link catches these errors but start did not. start now behaves as start_link if process traps exit. --- lib/stdlib/src/proc_lib.erl | 38 +++++++++++++++++++++++++++++++++----- lib/stdlib/test/proc_lib_SUITE.erl | 31 +++++++++++++++++++++++++++---- 2 files changed, 60 insertions(+), 9 deletions(-) (limited to 'lib') diff --git a/lib/stdlib/src/proc_lib.erl b/lib/stdlib/src/proc_lib.erl index 02bcbb5a60..4bca4c1e6d 100644 --- a/lib/stdlib/src/proc_lib.erl +++ b/lib/stdlib/src/proc_lib.erl @@ -1,7 +1,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 1996-2011. All Rights Reserved. +%% Copyright Ericsson AB 1996-2012. All Rights Reserved. %% %% The contents of this file are subject to the Erlang Public License, %% Version 1.1, (the "License"); you may not use this file except in @@ -184,6 +184,17 @@ check_for_monitor(SpawnOpts) -> false end. +spawn_mon(M,F,A) -> + Parent = get_my_name(), + Ancestors = get_ancestors(), + erlang:spawn_monitor(?MODULE, init_p, [Parent,Ancestors,M,F,A]). + +spawn_opt_mon(M, F, A, Opts) when is_atom(M), is_atom(F), is_list(A) -> + Parent = get_my_name(), + Ancestors = get_ancestors(), + check_for_monitor(Opts), + erlang:spawn_opt(?MODULE, init_p, [Parent,Ancestors,M,F,A], [monitor|Opts]). + -spec hibernate(Module, Function, Args) -> no_return() when Module :: module(), Function :: atom(), @@ -270,8 +281,8 @@ start(M, F, A) when is_atom(M), is_atom(F), is_list(A) -> Ret :: term() | {error, Reason :: term()}. start(M, F, A, Timeout) when is_atom(M), is_atom(F), is_list(A) -> - Pid = ?MODULE:spawn(M, F, A), - sync_wait(Pid, Timeout). + PidRef = spawn_mon(M, F, A), + sync_wait_mon(PidRef, Timeout). -spec start(Module, Function, Args, Time, SpawnOpts) -> Ret when Module :: module(), @@ -282,8 +293,8 @@ start(M, F, A, Timeout) when is_atom(M), is_atom(F), is_list(A) -> Ret :: term() | {error, Reason :: term()}. start(M, F, A, Timeout, SpawnOpts) when is_atom(M), is_atom(F), is_list(A) -> - Pid = ?MODULE:spawn_opt(M, F, A, SpawnOpts), - sync_wait(Pid, Timeout). + PidRef = spawn_opt_mon(M, F, A, SpawnOpts), + sync_wait_mon(PidRef, Timeout). -spec start_link(Module, Function, Args) -> Ret when Module :: module(), @@ -330,6 +341,23 @@ sync_wait(Pid, Timeout) -> {error, timeout} end. +sync_wait_mon({Pid, Ref}, Timeout) -> + receive + {ack, Pid, Return} -> + erlang:demonitor(Ref, [flush]), + Return; + {'DOWN', Ref, _Type, Pid, Reason} -> + {error, Reason}; + {'EXIT', Pid, Reason} -> %% link as spawn_opt? + erlang:demonitor(Ref, [flush]), + {error, Reason} + after Timeout -> + erlang:demonitor(Ref, [flush]), + exit(Pid, kill), + flush(Pid), + {error, timeout} + end. + -spec flush(pid()) -> 'true'. flush(Pid) -> diff --git a/lib/stdlib/test/proc_lib_SUITE.erl b/lib/stdlib/test/proc_lib_SUITE.erl index c95089117c..8dca69bac4 100644 --- a/lib/stdlib/test/proc_lib_SUITE.erl +++ b/lib/stdlib/test/proc_lib_SUITE.erl @@ -1,7 +1,7 @@ %% %% %CopyrightBegin% %% -%% Copyright Ericsson AB 1996-2011. All Rights Reserved. +%% Copyright Ericsson AB 1996-2012. All Rights Reserved. %% %% The contents of this file are subject to the Erlang Public License, %% Version 1.1, (the "License"); you may not use this file except in @@ -28,7 +28,7 @@ crash/1, sync_start_nolink/1, sync_start_link/1, spawn_opt/1, sp1/0, sp2/0, sp3/1, sp4/2, sp5/1, hibernate/1]). --export([ otp_6345/1]). +-export([ otp_6345/1, init_dont_hang/1]). -export([hib_loop/1, awaken/1]). @@ -36,7 +36,7 @@ handle_event/2, handle_call/2, handle_info/2, terminate/2]). --export([otp_6345_init/1]). +-export([otp_6345_init/1, init_dont_hang_init/1]). -ifdef(STANDALONE). @@ -52,7 +52,7 @@ all() -> {group, tickets}]. groups() -> - [{tickets, [], [otp_6345]}, + [{tickets, [], [otp_6345, init_dont_hang]}, {sync_start, [], [sync_start_nolink, sync_start_link]}]. init_per_suite(Config) -> @@ -343,6 +343,29 @@ otp_6345_loop() -> otp_6345_loop() end. +%% OTP-9803 +init_dont_hang(suite) -> + []; +init_dont_hang(doc) -> + ["Check that proc_lib:start don't hang if spawned process crashes before proc_lib:init_ack/2"]; +init_dont_hang(Config) when is_list(Config) -> + %% Start should behave as start_link + process_flag(trap_exit, true), + StartLinkRes = proc_lib:start_link(?MODULE, init_dont_hang_init, [self()]), + try + StartLinkRes = proc_lib:start(?MODULE, init_dont_hang_init, [self()], 1000), + StartLinkRes = proc_lib:start(?MODULE, init_dont_hang_init, [self()], 1000, []), + ok + catch _:Error -> + io:format("Error ~p /= ~p ~n",[erlang:get_stacktrace(), StartLinkRes]), + exit(Error) + end. + +init_dont_hang_init(Parent) -> + 1 = 2. + + + %%----------------------------------------------------------------- %% The error_logger handler used. %%----------------------------------------------------------------- -- cgit v1.2.3