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-rw-r--r--erts/emulator/beam/erl_bif_info.c2
-rw-r--r--erts/emulator/test/process_SUITE.erl84
2 files changed, 65 insertions, 21 deletions
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 2704b99aa4..0339589b79 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -768,7 +768,7 @@ static ErtsProcessInfoArgs pi_args[] = {
{am_memory, 0, ERTS_PI_FLAG_NEED_MSGQ_LEN|ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
{am_garbage_collection, 3+2 + 3+2 + 3+2 + 3+2 + 3+2 + ERTS_MAX_HEAP_SIZE_MAP_SZ, 0, ERTS_PROC_LOCK_MAIN},
{am_group_leader, 0, 0, ERTS_PROC_LOCK_MAIN},
- {am_reductions, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+ {am_reductions, 0, 0, ERTS_PROC_LOCK_MAIN},
{am_priority, 0, 0, 0},
{am_trace, 0, 0, ERTS_PROC_LOCK_MAIN},
{am_binary, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index b530ced566..3684cde8d4 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -1098,42 +1098,86 @@ process_info_status_handled_signal(Config) when is_list(Config) ->
%% OTP-15709
%% Provoke a bug where process_info(reductions) returned wrong result
%% because REDS_IN (def_arg_reg[5]) is read when the process in not running.
+%%
+%% And a bug where process_info(reductions) on a process which was releasing its
+%% main lock during execution could result in negative reduction diffs.
process_info_reductions(Config) when is_list(Config) ->
- pi_reductions_tester(spawn_link(fun() -> pi_reductions_spinnloop() end)),
- pi_reductions_tester(spawn_link(fun() -> pi_reductions_recvloop() end)),
+ {S1, S2} = case erlang:system_info(schedulers) of
+ 1 -> {1,1};
+ _ -> {1,2}
+ end,
+ io:format("Run on schedulers ~p and ~p\n", [S1,S2]),
+ Boss = self(),
+ Doer = spawn_opt(fun () ->
+ pi_reductions_tester(true, 10, fun pi_reductions_spinnloop/0, S2),
+ pi_reductions_tester(true, 10, fun pi_reductions_recvloop/0, S2),
+ pi_reductions_tester(false, 100, fun pi_reductions_main_unlocker/0, S2),
+ Boss ! {self(), done}
+ end,
+ [link, {scheduler, S1}]),
+
+ {Doer, done} = receive M -> M end,
ok.
-pi_reductions_tester(Pid) ->
- {_, DiffList} =
- lists:foldl(fun(_, {Prev, Acc}) ->
- %% Add another item that force sending the request
- %% as a signal, like 'current_function'.
- PI = process_info(Pid, [reductions, current_function]),
- [{reductions,Reds}, {current_function,_}] = PI,
- Diff = Reds - Prev,
- {Diff, true} = {Diff, (Diff >= 0)},
- {Diff, true} = {Diff, (Diff =< 1000*1000)},
- {Reds, [Diff | Acc]}
- end,
- {0, []},
- lists:seq(1,10)),
+pi_reductions_tester(ForceSignal, MaxCalls, Fun, S2) ->
+ Pid = spawn_opt(Fun, [link, {scheduler,S2}]),
+ Extra = case ForceSignal of
+ true ->
+ %% Add another item that force sending the request
+ %% as a signal, like 'current_function'.
+ [current_function];
+ false ->
+ []
+ end,
+ LoopFun = fun Me(Calls, Prev, Acc0) ->
+ PI = process_info(Pid, [reductions | Extra]),
+ [{reductions,Reds} | _] = PI,
+ Diff = Reds - Prev,
+ %% Verify we get sane non-negative reduction diffs
+ {Diff, true} = {Diff, (Diff >= 0)},
+ {Diff, true} = {Diff, (Diff =< 1000*1000)},
+ Acc1 = [Diff | Acc0],
+ case Calls >= MaxCalls of
+ true -> Acc1;
+ false -> Me(Calls+1, Reds, Acc1)
+ end
+ end,
+ DiffList = LoopFun(0, 0, []),
unlink(Pid),
exit(Pid,kill),
- io:format("Reduction diffs: ~p\n", [DiffList]),
+ io:format("Reduction diffs: ~p\n", [lists:reverse(DiffList)]),
ok.
pi_reductions_spinnloop() ->
%% 6 args to make use of def_arg_reg[5] which is also used as REDS_IN
- pi_reductions_spinnloop(1, atom, "hej", self(), make_ref(), 3.14).
+ pi_reductions_spinnloop(999*1000, atom, "hej", self(), make_ref(), 3.14).
-pi_reductions_spinnloop(A,B,C,D,E,F) ->
- pi_reductions_spinnloop(B,C,D,E,F,A).
+pi_reductions_spinnloop(N,A,B,C,D,E) when N > 0 ->
+ pi_reductions_spinnloop(N-1,B,C,D,E,A);
+pi_reductions_spinnloop(0,_,_,_,_,_) ->
+ %% Stop to limit max number of reductions consumed
+ pi_reductions_recvloop().
pi_reductions_recvloop() ->
receive
"a free lunch" -> false
end.
+pi_reductions_main_unlocker() ->
+ Other = spawn_link(fun() -> receive die -> ok end end),
+ pi_reductions_main_unlocker_loop(Other).
+
+pi_reductions_main_unlocker_loop(Other) ->
+ %% Assumption: register(OtherPid, Name) will unlock main lock of calling
+ %% process during execution.
+ register(pi_reductions_main_unlocker, Other),
+ unregister(pi_reductions_main_unlocker),
+
+ %% Yield in order to increase probability of process_info sometimes probing
+ %% this process when it's not RUNNING.
+ erlang:yield(),
+ pi_reductions_main_unlocker_loop(Other).
+
%% Tests erlang:bump_reductions/1.
bump_reductions(Config) when is_list(Config) ->