From e19d6e4463a9cc3b738fd32a46e0ce9282a70fd5 Mon Sep 17 00:00:00 2001 From: Rickard Green Date: Fri, 22 Jan 2010 13:47:23 +0000 Subject: OTP-8386 Immediately repeated multi-scheduling block/unblock cycles using erlang:system_flag(multi_scheduling, block | unblock) could deadlock the runtime system. --- erts/emulator/beam/erl_process.c | 22 ++++--- erts/emulator/test/scheduler_SUITE.erl | 110 ++++++++++++++++++++++++++++++--- 2 files changed, 115 insertions(+), 17 deletions(-) diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c index 476e29d96f..b519b39d63 100644 --- a/erts/emulator/beam/erl_process.c +++ b/erts/emulator/beam/erl_process.c @@ -2522,8 +2522,11 @@ suspend_scheduler(ErtsSchedulerData *esdp) NULL); } - erts_smp_atomic_inc(&schdlr_sspnd.active); - + active_schedulers = erts_smp_atomic_inctest(&schdlr_sspnd.active); + if (schdlr_sspnd.changing == ERTS_SCHED_CHANGING_MULTI_SCHED + && schdlr_sspnd.online == active_schedulers) { + schdlr_sspnd.changing = 0; + } erts_smp_mtx_unlock(&schdlr_sspnd.mtx); if (erts_system_profile_flags.scheduler) @@ -2750,11 +2753,12 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all) ErtsProcList *plp; erts_smp_mtx_lock(&schdlr_sspnd.mtx); - if (on) { - if (schdlr_sspnd.changing) { - res = ERTS_SCHDLR_SSPND_YIELD_RESTART; /* Yield */ - } - else if (erts_is_multi_scheduling_blocked()) { + + if (schdlr_sspnd.changing) { + res = ERTS_SCHDLR_SSPND_YIELD_RESTART; /* Yield */ + } + else if (on) { /* ------ BLOCK ------ */ + if (erts_is_multi_scheduling_blocked()) { plp = proclist_create(p); plp->next = schdlr_sspnd.msb.procs; schdlr_sspnd.msb.procs = plp; @@ -2842,10 +2846,11 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all) } } else if (!ongoing_multi_scheduling_block()) { + /* unblock not ongoing */ ASSERT(!schdlr_sspnd.msb.procs); res = ERTS_SCHDLR_SSPND_DONE; } - else { + else { /* ------ UNBLOCK ------ */ if (p->flags & F_HAVE_BLCKD_MSCHED) { ErtsProcList **plpp = &schdlr_sspnd.msb.procs; plp = schdlr_sspnd.msb.procs; @@ -2930,7 +2935,6 @@ erts_block_multi_scheduling(Process *p, ErtsProcLocks plocks, int on, int all) erts_smp_mtx_lock(&schdlr_sspnd.mtx); } erts_smp_cnd_broadcast(&schdlr_sspnd.cnd); - schdlr_sspnd.changing = 0; res = ERTS_SCHDLR_SSPND_DONE; } } diff --git a/erts/emulator/test/scheduler_SUITE.erl b/erts/emulator/test/scheduler_SUITE.erl index e644ad4dc8..c9101b77c2 100644 --- a/erts/emulator/test/scheduler_SUITE.erl +++ b/erts/emulator/test/scheduler_SUITE.erl @@ -1,19 +1,19 @@ %% %% %CopyrightBegin% -%% -%% Copyright Ericsson AB 2008-2009. All Rights Reserved. -%% +%% +%% Copyright Ericsson AB 2008-2010. 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 %% compliance with the License. You should have received a copy of the %% Erlang Public License along with this software. If not, it can be %% retrieved online at http://www.erlang.org/. -%% +%% %% 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. -%% +%% %% %CopyrightEnd% %% @@ -48,7 +48,8 @@ scheduler_bind_types/1, cpu_topology/1, sct_cmd/1, - sbt_cmd/1]). + sbt_cmd/1, + scheduler_suspend/1]). -define(DEFAULT_TIMEOUT, ?t:minutes(10)). @@ -65,7 +66,8 @@ all(suite) -> equal_with_high, equal_with_high_max, bound_process, - scheduler_bind]. + scheduler_bind, + scheduler_suspend]. init_per_testcase(Case, Config) when is_list(Config) -> Dog = ?t:timetrap(?DEFAULT_TIMEOUT), @@ -882,11 +884,103 @@ sbt_test(Config, CpuTCmd, ClBt, Bt, LP) -> ?line stop_node(Node), ?line ok. +scheduler_suspend(Config) when is_list(Config) -> + ?line Dog = ?t:timetrap(?t:minutes(2)), + ?line lists:foreach(fun (S) -> scheduler_suspend_test(Config, S) end, + [64, 32, 16, default]), + ?line ?t:timetrap_cancel(Dog), + ?line ok. +scheduler_suspend_test(Config, Schedulers) -> + ?line Cmd = case Schedulers of + default -> + ""; + _ -> + S = integer_to_list(Schedulers), + "+S"++S++":"++S + end, + ?line {ok, Node} = start_node(Config, Cmd), + ?line [SState] = mcall(Node, [fun () -> + erlang:system_info(schedulers_state) + end]), + ?line {Sched, _, _} = SState, + ?line true = is_integer(Sched), + ?line [ok] = mcall(Node, [fun () -> sst0_loop(300) end]), + ?line [ok] = mcall(Node, [fun () -> sst1_loop(300) end]), + ?line [ok] = mcall(Node, [fun () -> sst2_loop(300) end]), + ?line [ok, ok, ok, ok, ok] = mcall(Node, + [fun () -> sst0_loop(200) end, + fun () -> sst1_loop(200) end, + fun () -> sst2_loop(200) end, + fun () -> sst2_loop(200) end, + fun () -> sst3_loop(Sched, 200) end]), + ?line [SState] = mcall(Node, [fun () -> + erlang:system_info(schedulers_state) + end]), + ?line stop_node(Node), + ?line ok. + + +sst0_loop(0) -> + ok; +sst0_loop(N) -> + erlang:system_flag(multi_scheduling, block), + erlang:system_flag(multi_scheduling, unblock), + erlang:yield(), + sst0_loop(N-1). + +sst1_loop(0) -> + ok; +sst1_loop(N) -> + erlang:system_flag(multi_scheduling, block), + erlang:system_flag(multi_scheduling, unblock), + sst1_loop(N-1). + +sst2_loop(0) -> + ok; +sst2_loop(N) -> + erlang:system_flag(multi_scheduling, block), + erlang:system_flag(multi_scheduling, block), + erlang:system_flag(multi_scheduling, block), + erlang:system_flag(multi_scheduling, unblock), + erlang:system_flag(multi_scheduling, unblock), + erlang:system_flag(multi_scheduling, unblock), + sst2_loop(N-1). + +sst3_loop(_S, 0) -> + ok; +sst3_loop(S, N) -> + erlang:system_flag(schedulers_online, (S div 2)+1), + erlang:system_flag(schedulers_online, 1), + erlang:system_flag(schedulers_online, (S div 2)+1), + erlang:system_flag(schedulers_online, S), + erlang:system_flag(schedulers_online, 1), + erlang:system_flag(schedulers_online, S), + sst3_loop(S, N-1). + -% +%% %% Utils %% +mcall(Node, Funs) -> + Parent = self(), + Refs = lists:map(fun (Fun) -> + Ref = make_ref(), + spawn_link(Node, + fun () -> + Res = Fun(), + unlink(Parent), + Parent ! {Ref, Res} + end), + Ref + end, Funs), + lists:map(fun (Ref) -> + receive + {Ref, Res} -> + Res + end + end, Refs). + erl_rel_flag_var() -> "ERL_"++erlang:system_info(otp_release)++"_FLAGS". -- cgit v1.2.3