Implementation of true asynchronous signaling between processes

Communication between Erlang processes has conceptually always been
performed through asynchronous signaling. The runtime system
implementation has however previously preformed most operation
synchronously. In a system with only one true thread of execution, this
is not problematic (often the opposite). In a system with multiple threads
of execution (as current runtime system implementation with SMP support)
it becomes problematic. This since it often involves locking of structures
when updating them which in turn cause resource contention. Utilizing
true asynchronous communication often avoids these resource contention
issues.

The case that triggered this change was contention on the link lock due
to frequent updates of the monitor trees during communication with a
frequently used server. The signal order delivery guarantees of the
language makes it hard to change the implementation of only some signals
to use true asynchronous signaling. Therefore the implementations
of (almost) all signals have been changed.

Currently the following signals have been implemented as true
asynchronous signals:
- Message signals
- Exit signals
- Monitor signals
- Demonitor signals
- Monitor triggered signals (DOWN, CHANGE, etc)
- Link signals
- Unlink signals
- Group leader signals

All of the above already defined as asynchronous signals in the
language. The implementation of messages signals was quite
asynchronous to begin with, but had quite strict delivery constraints
due to the ordering guarantees of signals between a pair of processes.

The previously used message queue partitioned into two halves has been
replaced by a more general signal queue partitioned into three parts
that service all kinds of signals. More details regarding the signal
queue can be found in comments in the erl_proc_sig_queue.h file.

The monitor and link implementations have also been completely replaced
in order to fit the new asynchronous signaling implementation as good
as possible. More details regarding the new monitor and link
implementations can be found in the erl_monitor_link.h file.

9 files changed, 374 insertions, 618 deletions

diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl
index e1b42e5d85..d16c6a320d 100644
--- a/erts/emulator/test/bif_SUITE.erl
+++ b/erts/emulator/test/bif_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 2005-2016. All Rights Reserved.
+%% Copyright Ericsson AB 2005-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -33,7 +33,8 @@
 	 atom_to_binary/1,min_max/1, erlang_halt/1,
          erl_crash_dump_bytes/1,
 	 is_builtin/1, error_stacktrace/1,
-	 error_stacktrace_during_call_trace/1]).
+	 error_stacktrace_during_call_trace/1,
+         group_leader_prio/1, group_leader_prio_dirty/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]},
@@ -46,7 +47,8 @@ all() ->
      display, display_string, list_to_utf8_atom,
      atom_to_binary, binary_to_atom, binary_to_existing_atom,
      erl_crash_dump_bytes, min_max, erlang_halt, is_builtin,
-     error_stacktrace, error_stacktrace_during_call_trace].
+     error_stacktrace, error_stacktrace_during_call_trace,
+     group_leader_prio, group_leader_prio_dirty].
 
 %% Uses erlang:display to test that erts_printf does not do deep recursion
 display(Config) when is_list(Config) ->
@@ -825,7 +827,6 @@ error_stacktrace_during_call_trace(Config) when is_list(Config) ->
 	end
     end,
     ok.
-    
 
 error_stacktrace_test() ->
     Types = [apply_const_last, apply_const, apply_last,
@@ -963,9 +964,119 @@ do_error_1(call) ->
     erlang:error(id(oops)).
 
 
+group_leader_prio(Config) when is_list(Config) ->
+    group_leader_prio_test(false).
+
+group_leader_prio_dirty(Config) when is_list(Config) ->
+    group_leader_prio_test(true).
+
+group_leader_prio_test(Dirty) ->
+    %%
+    %% Unfortunately back in the days node local group_leader/2 was not
+    %% implemented as sending an asynchronous signal to the process to change
+    %% group leader for. Instead it has always been synchronously changed, and
+    %% nothing in the documentation have hinted otherwise... Therefore I do not
+    %% dare the change this.
+    %%
+    %% In order to prevent priority inversion, the priority of the receiver of
+    %% the group leader signal is elevated while handling incoming signals if
+    %% the sender has a higher priority than the receiver. This test tests that
+    %% the priority elevation actually works...
+    %%
+    Tester = self(),
+    Init = erlang:whereis(init),
+    GL = erlang:group_leader(),
+    process_flag(priority, max),
+    {TestProcFun, NTestProcs}
+        = case Dirty of
+              false ->
+                  %% These processes will handle all incoming signals
+                  %% by them selves...
+                  {fun () ->
+                           Tester ! {alive, self()},
+                           receive after infinity -> ok end
+                   end,
+                   100};
+              true ->
+                  %% These processes wont handle incoming signals by
+                  %% them selves since they are stuck on dirty schedulers
+                  %% when we try to change group leader. A dirty process
+                  %% signal handler process (system process) will be notified
+                  %% of the need to handle incoming signals for these processes,
+                  %% and will instead handle the signal for these processes...
+                  {fun () ->
+                           %% The following sends the message '{alive, self()}'
+                           %% to Tester once on a dirty io scheduler, then wait
+                           %% there until the process terminates...
+                           erts_debug:dirty_io(alive_waitexiting, Tester)
+                   end,
+                   erlang:system_info(dirty_io_schedulers)}
+          end,
+    TPs = lists:map(fun (_) ->
+                            spawn_opt(TestProcFun,
+                                      [link, {priority, normal}])
+                    end, lists:seq(1, NTestProcs)),
+    lists:foreach(fun (TP) -> receive {alive, TP} -> ok end end, TPs),
+    TLs = lists:map(fun (_) ->
+                            spawn_opt(fun () -> tok_loop() end,
+                                      [link, {priority, high}])
+                    end,
+                    lists:seq(1, 2*erlang:system_info(schedulers))),
+    %% Wait to ensure distribution of high prio processes over schedulers...
+    receive after 1000 -> ok end,
+    %%
+    %% Test that we can get group-leader signals through to normal prio
+    %% processes from a max prio process even though all schedulers are filled
+    %% with executing high prio processes.
+    %%
+    lists:foreach(fun (_) ->
+                          lists:foreach(fun (TP) ->
+                                                erlang:yield(),
+                                                %% whitebox -- Enqueue some signals on it
+                                                %% preventing us from hogging its main lock
+                                                %% and set group-leader directly....
+                                                erlang:demonitor(erlang:monitor(process, TP)),
+                                                true = erlang:group_leader(Init, TP),
+                                                {group_leader, Init} = process_info(TP, group_leader),
+                                                erlang:demonitor(erlang:monitor(process, TP)),
+                                                true = erlang:group_leader(GL, TP),
+                                                {group_leader, GL} = process_info(TP, group_leader)
+                                        end,
+                                        TPs)
+                  end,
+                  lists:seq(1,100)),
+    %%
+    %% Also test when it is exiting...
+    %%
+    lists:foreach(fun (TP) ->
+                          erlang:yield(),
+                          M = erlang:monitor(process, TP),
+                          unlink(TP),
+                          exit(TP, bang),
+                          badarg = try
+                                       true = erlang:group_leader(Init, TP)
+                                   catch
+                                       error : What -> What
+                                   end,
+                          receive
+                              {'DOWN', M, process, TP, Reason} ->
+                                  bang = Reason
+                          end
+                  end,
+                  TPs),
+    lists:foreach(fun (TL) ->
+                          M = erlang:monitor(process, TL),
+                          unlink(TL),
+                          exit(TL, bang),
+                          receive
+                              {'DOWN', M, process, TL, Reason} ->
+                                  bang = Reason
+                          end
+                  end,
+                  TLs),
+    ok.
 
-
-%% Helpers
+%% helpers
     
 id(I) -> I.
 
@@ -1005,3 +1116,11 @@ hostname([$@ | Hostname]) ->
     list_to_atom(Hostname);
 hostname([_C | Cs]) ->
     hostname(Cs).
+
+tok_loop() ->
+    tok_loop(hej).
+
+tok_loop(hej) ->
+    tok_loop(hopp);
+tok_loop(hopp) ->
+    tok_loop(hej).
diff --git a/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c b/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
index 2a8b999307..a94a2c0b02 100644
--- a/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
+++ b/erts/emulator/test/dirty_nif_SUITE_data/dirty_nif_SUITE.c
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  *
- * Copyright Ericsson AB 2009-2017. All Rights Reserved.
+ * Copyright Ericsson AB 2009-2018. All Rights Reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -112,15 +112,12 @@ static ERL_NIF_TERM send_from_dirty_nif(ErlNifEnv* env, int argc, const ERL_NIF_
 {
     ERL_NIF_TERM result;
     ErlNifPid pid;
-    ErlNifEnv* menv;
     int res;
 
     if (!enif_get_local_pid(env, argv[0], &pid))
 	return enif_make_badarg(env);
     result = enif_make_tuple2(env, enif_make_atom(env, "ok"), enif_make_pid(env, &pid));
-    menv = enif_alloc_env();
-    res = enif_send(env, &pid, menv, result);
-    enif_free_env(menv);
+    res = enif_send(env, &pid, NULL, result);
     if (!res)
 	return enif_make_badarg(env);
     else
@@ -131,15 +128,12 @@ static ERL_NIF_TERM send_wait_from_dirty_nif(ErlNifEnv* env, int argc, const ERL
 {
     ERL_NIF_TERM result;
     ErlNifPid pid;
-    ErlNifEnv* menv;
     int res;
 
     if (!enif_get_local_pid(env, argv[0], &pid))
 	return enif_make_badarg(env);
     result = enif_make_tuple2(env, enif_make_atom(env, "ok"), enif_make_pid(env, &pid));
-    menv = enif_alloc_env();
-    res = enif_send(env, &pid, menv, result);
-    enif_free_env(menv);
+    res = enif_send(env, &pid, NULL, result);
 
 #ifdef __WIN32__
     Sleep(2000);
@@ -211,10 +205,8 @@ dirty_sleeper(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     /* If we get a pid argument, it indicates a process involved in the
        test wants a message from us. Prior to the sleep we send a 'ready'
        message, and then after the sleep, send a 'done' message. */
-    if (argc == 1 && enif_get_local_pid(env, argv[0], &pid)) {
-        msg_env = enif_alloc_env();
-        enif_send(env, &pid, msg_env, enif_make_atom(msg_env, "ready"));
-    }
+    if (argc == 1 && enif_get_local_pid(env, argv[0], &pid))
+        enif_send(env, &pid, NULL, enif_make_atom(env, "ready"));
 
 #ifdef __WIN32__
     Sleep(2000);
@@ -222,11 +214,8 @@ dirty_sleeper(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     sleep(2);
 #endif
 
-    if (argc == 1) {
-        assert(msg_env != NULL);
-        enif_send(env, &pid, msg_env, enif_make_atom(msg_env, "done"));
-        enif_free_env(msg_env);
-    }
+    if (argc == 1)
+        enif_send(env, &pid, NULL, enif_make_atom(env, "done"));
 
     return enif_make_atom(env, "ok");
 }
@@ -247,8 +236,8 @@ static ERL_NIF_TERM dirty_call_while_terminated_nif(ErlNifEnv* env, int argc, co
 
     self_term = enif_make_pid(env, &self);
 
-    result = enif_make_tuple2(env, enif_make_atom(env, "dirty_alive"), self_term);
     menv = enif_alloc_env();
+    result = enif_make_tuple2(menv, enif_make_atom(menv, "dirty_alive"), self_term);
     res = enif_send(env, &to, menv, result);
     enif_free_env(menv);
     if (!res)
@@ -259,9 +248,7 @@ static ERL_NIF_TERM dirty_call_while_terminated_nif(ErlNifEnv* env, int argc, co
 	;
 
     result = enif_make_tuple2(env, enif_make_atom(env, "dirty_dead"), self_term);
-    menv = enif_alloc_env();
-    res = enif_send(env, &to, menv, result);
-    enif_free_env(menv);
+    res = enif_send(env, &to, NULL, result);
 
 #ifdef __WIN32__
     Sleep(1000);
diff --git a/erts/emulator/test/erl_link_SUITE.erl b/erts/emulator/test/erl_link_SUITE.erl
index a66ca7a57d..ed444f2599 100644
--- a/erts/emulator/test/erl_link_SUITE.erl
+++ b/erts/emulator/test/erl_link_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 2001-2017. All Rights Reserved.
+%% Copyright Ericsson AB 2001-2018. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -53,26 +53,17 @@
 -export([test_proc/0]).
 
 
--define(LINK_UNDEF, 0).
--define(LINK_PID,   1).
--define(LINK_NODE,  3).
-
-
-% These are to be kept in sync with erl_monitors.h 
--define(MON_ORIGIN, 1).
--define(MON_TARGET, 2).
-
-
--record(erl_link, {type = ?LINK_UNDEF,
+-record(erl_link, {type,           % process | port | dist_process
                    pid = [],
-                   targets = []}).
+                   id}).
 
 % This is to be kept in sync with erl_bif_info.c (make_monitor_list)
 
--record(erl_monitor, {type,        % MON_ORIGIN or MON_TARGET
-                      ref,
+-record(erl_monitor, {type,        % process | port | time_offset | dist_process | resource | node | nodes | suspend
+                      dir,         % origin | target
+                      ref,         % Reference | []
                       pid,         % Process or nodename
-                      name = []}). % registered name or []
+                      extra = []}). % registered name, integer or, []
 
 
 suite() ->
@@ -106,7 +97,7 @@ end_per_suite(_Config) ->
 links(Config) when is_list(Config) ->
     common_link_test(node(), node()),
     true = link(self()),
-    [] = find_erl_link(self(), ?LINK_PID, self()),
+    [] = find_erl_link(self(), process, self()),
     true = unlink(self()),
     ok.
 
@@ -191,6 +182,7 @@ monitor_nodes(Config) when is_list(Config) ->
     monitor_node(A, false),
     monitor_node(B, true),
     monitor_node(C, true),
+    receive after 1000 -> ok end,
     monitor_node(C, false),
     monitor_node(C, true),
     monitor_node(B, true),
@@ -304,7 +296,8 @@ run_common_process_monitors(TP1, TP2) ->
     wait_until(fun () -> is_proc_dead(TP2) end),
     ok = tp_call(TP1, fun () ->
                               receive
-                                  {'DOWN',R2,process,TP2O,bye} ->
+                                  {'DOWN',R2,process,TP2O,Reason1} ->
+                                      bye = Reason1,
                                       ok
                               end
                       end),
@@ -313,7 +306,8 @@ run_common_process_monitors(TP1, TP2) ->
     R3 = tp_call(TP1, fun () -> erlang:monitor(process, TP2) end),
     ok = tp_call(TP1, fun () ->
                               receive
-                                  {'DOWN',R3,process,TP2O,noproc} ->
+                                  {'DOWN',R3,process,TP2O,Reason2} ->
+                                      noproc = Reason2,
                                       ok
                               end
                       end),
@@ -698,22 +692,10 @@ test_proc() ->
     end,
     test_proc().
 
-expand_link_list([#erl_link{type = ?LINK_NODE, targets = N} = Rec | T]) ->
-    lists:duplicate(N,Rec#erl_link{targets = []}) ++ expand_link_list(T);
-expand_link_list([#erl_link{targets = [#erl_link{pid = Pid}]} = Rec | T]) ->
-    [Rec#erl_link{targets = [Pid]} | expand_link_list(T)];
-expand_link_list([#erl_link{targets = [#erl_link{pid = Pid}|TT]} = Rec | T]) ->
-    [ Rec#erl_link{targets = [Pid]} | expand_link_list( 
-                                        [Rec#erl_link{targets = TT} | T])]; 
-expand_link_list([#erl_link{targets = []} = Rec | T]) ->
-    [Rec | expand_link_list(T)];
-expand_link_list([]) ->
-    [].
-
 get_local_link_list(Obj) ->
     case catch erts_debug:get_internal_state({link_list, Obj}) of
         LL when is_list(LL) ->
-            expand_link_list(LL);
+            LL;
         _ ->
             []
     end.
@@ -722,7 +704,7 @@ get_remote_link_list(Node, Obj) ->
     case catch rpc:call(Node, erts_debug, get_internal_state,
                         [{link_list, Obj}]) of
         LL when is_list(LL) ->
-            expand_link_list(LL);
+            LL;
         _ ->
             []
     end.
@@ -776,82 +758,106 @@ get_monitor_list(undefined) ->
 
 
 find_erl_monitor(Pid, Ref) when is_reference(Ref) ->
+    MonitorList = get_monitor_list(Pid),
+    io:format("~p MonitorList: ~p~n", [Pid, MonitorList]),
     lists:foldl(fun (#erl_monitor{ref = R} = EL, Acc) when R == Ref ->
                         [EL|Acc];
                     (_, Acc) ->
                         Acc
                 end,
                 [],
-                get_monitor_list(Pid)).
-
-% find_erl_link(Obj, Ref) when is_reference(Ref) -> 
-%     lists:foldl(fun (#erl_link{ref = R} = EL, Acc) when R == Ref ->
-% 			      [EL|Acc];
-% 			  (_, Acc) ->
-% 			      Acc
-% 		      end,
-% 		      [],
-% 		      get_link_list(Obj)).
-
-find_erl_link(Obj, Type, [Item, Data]) when is_pid(Item);
-                                            is_port(Item);
-                                            is_atom(Item) -> 
-    lists:foldl(fun (#erl_link{type = T, pid = I, targets = D} = EL,
+                MonitorList);
+find_erl_monitor(Pid, Item) ->
+    MonitorList = get_monitor_list(Pid),
+    io:format("~p MonitorList: ~p~n", [Pid, MonitorList]),
+    lists:foldl(fun (#erl_monitor{pid = I} = EL, Acc) when I == Item ->
+                        [EL|Acc];
+                    (_, Acc) ->
+                        Acc
+                end,
+                [],
+                MonitorList).
+
+
+find_erl_link(Obj, Type, Item) when is_pid(Item); is_port(Item) -> 
+    LinkList = get_link_list(Obj),
+    io:format("~p LinkList: ~p~n", [Obj, LinkList]),
+    lists:foldl(fun (#erl_link{type = T, pid = I} = EL,
                      Acc) when T == Type, I == Item ->
-                        case Data of
-                            D ->
-                                [EL|Acc];
-                            [] ->
-                                [EL|Acc];
-                            _ ->
-                                Acc
-                        end;
+                        [EL|Acc];
+                    (_, Acc) ->
+                        Acc
+                end,
+                [],
+                LinkList);
+find_erl_link(Obj, Type, Id) when is_integer(Id) -> 
+    %% Find by Id
+    LinkList = get_link_list(Obj),
+    io:format("~p LinkList: ~p~n", [Obj, LinkList]),
+    lists:foldl(fun (#erl_link{type = T, id = I} = EL,
+                     Acc) when T == Type, I == Id ->
+                        [EL|Acc];
                     (_, Acc) ->
                         Acc
                 end,
                 [],
-                get_link_list(Obj));
-find_erl_link(Obj, Type, Item) when is_pid(Item); is_port(Item); is_atom(Item) ->
-    find_erl_link(Obj, Type, [Item, []]). 
+                LinkList).
 
 
+get_link_type(A, B) when is_port(A);
+                         is_port(B) ->
+    port;
+get_link_type(A, B) when is_pid(A),
+                         is_pid(B) ->
+    case node(A) == node(B) of
+        true ->
+            process;
+        false ->
+            dist_process
+    end.
 
+check_link(A, B) when node(A) == node(B) ->
+    LinkType = get_link_type(A, B),
+    [#erl_link{type = LinkType,
+               pid = B,
+               id = Id}] = find_erl_link(A, LinkType, B),
+    [#erl_link{type = LinkType,
+               pid = A,
+               id = Id}] = find_erl_link(B, LinkType, A),
+    [] = find_erl_link({node(A), node(B)},
+                       LinkType,
+                       A),
+    [] = find_erl_link({node(B), node(A)},
+                       LinkType,
+                       B),
+    ok;
 check_link(A, B) ->
-    [#erl_link{type = ?LINK_PID,
+    [#erl_link{type = dist_process,
                pid = B,
-               targets = []}] = find_erl_link(A, ?LINK_PID, B),
-    [#erl_link{type = ?LINK_PID,
+               id = IdA}] = find_erl_link(A, dist_process, B),
+    [#erl_link{type = dist_process,
                pid = A,
-               targets = []}] = find_erl_link(B, ?LINK_PID, A),
-    case node(A) == node(B) of
-        false ->
-            [#erl_link{type = ?LINK_PID,
-                       pid = A,
-                       targets = [B]}] = find_erl_link({node(A),
-                                                        node(B)},
-                                                       ?LINK_PID,
-                                                       [A, [B]]),
-            [#erl_link{type = ?LINK_PID,
-                       pid = B,
-                       targets = [A]}] = find_erl_link({node(B),
-                                                        node(A)},
-                                                       ?LINK_PID,
-                                                       [B, [A]]);
-        true ->
-            [] = find_erl_link({node(A), node(B)},
-                               ?LINK_PID,
-                               [A, [B]]),
-            [] = find_erl_link({node(B), node(A)},
-                               ?LINK_PID,
-                               [B, [A]])
-    end,
+               id = IdA}] = find_erl_link({node(A),
+                                           node(B)},
+                                          dist_process,
+                                          IdA),
+    [#erl_link{type = dist_process,
+               pid = A,
+               id = IdB}] = find_erl_link(B, dist_process, A),
+    [#erl_link{type = dist_process,
+               pid = B,
+               id = IdB}] = find_erl_link({node(B),
+                                           node(A)},
+                                          dist_process,
+                                          IdB),
     ok.
 
 check_unlink(A, B) ->
-    [] = find_erl_link(A, ?LINK_PID, B),
-    [] = find_erl_link(B, ?LINK_PID, A),
-    [] = find_erl_link({node(A), node(B)}, ?LINK_PID, [A, [B]]),
-    [] = find_erl_link({node(B), node(A)}, ?LINK_PID, [B, [A]]),
+    LinkType = get_link_type(A, B),
+    [] = find_erl_link(A, LinkType, B),
+    [] = find_erl_link(B, LinkType, A),
+    [] = find_erl_link({node(A), node(B)}, dist_process, A),
+    [] = find_erl_link({node(B), node(A)}, dist_process, B),
     ok.
 
 check_process_monitor(From, {Name, Node}, Ref) when is_pid(From),
@@ -864,22 +870,26 @@ check_process_monitor(From, {Name, Node}, Ref) when is_pid(From),
                                                     is_atom(Node),
                                                     is_reference(Ref) ->
     MonitoredPid = rpc:call(Node, erlang, whereis, [Name]),
-    [#erl_monitor{type = ?MON_ORIGIN,
+    [#erl_monitor{type = dist_process,
+                  dir = origin,
                   ref = Ref,
                   pid = Node,
-                  name = Name}] = find_erl_monitor(From, Ref),
-    [#erl_monitor{type = ?MON_TARGET,
+                  extra = Name}] = find_erl_monitor(From, Ref),
+    [#erl_monitor{type = dist_process,
+                  dir = target,
                   ref = Ref,
                   pid = From,
-                  name = Name}] = 	find_erl_monitor({node(From), Node}, Ref),
-    [#erl_monitor{type = ?MON_ORIGIN,
+                  extra = Name}] = find_erl_monitor({node(From), Node}, Ref),
+    [#erl_monitor{type = dist_process,
+                  dir = origin,
                   ref = Ref,
                   pid = MonitoredPid,
-                  name = Name}] = find_erl_monitor({Node, node(From)}, Ref),
-    [#erl_monitor{type = ?MON_TARGET,
+                  extra = Name}] = find_erl_monitor({Node, node(From)}, Ref),
+    [#erl_monitor{type = dist_process,
+                  dir = target,
                   ref = Ref,
                   pid = From,
-                  name = Name}] = find_erl_monitor(MonitoredPid, Ref),
+                  extra = Name}] = find_erl_monitor(MonitoredPid, Ref),
     ok;
 check_process_monitor(From, Name, Ref) when is_pid(From),
                                             is_atom(Name),
@@ -887,27 +897,36 @@ check_process_monitor(From, Name, Ref) when is_pid(From),
                                             is_reference(Ref) ->
     MonitoredPid = rpc:call(node(From), erlang, whereis, [Name]),
 
-    [#erl_monitor{type = ?MON_ORIGIN,
+    [#erl_monitor{type = process,
+                  dir = origin,
                   ref = Ref,
                   pid = MonitoredPid,
-                  name = Name}] = find_erl_monitor(From, Ref),
+                  extra = Name}] = find_erl_monitor(From, Ref),
 
 
-    [#erl_monitor{type = ?MON_TARGET,
+    [#erl_monitor{type = process,
+                  dir = target,
                   ref = Ref,
                   pid = From,
-                  name = Name}] = find_erl_monitor(MonitoredPid,Ref),
+                  extra = Name}] = find_erl_monitor(MonitoredPid,Ref),
     ok;
 check_process_monitor(From, To, Ref) when is_pid(From),
                                           is_pid(To),
                                           is_reference(Ref) ->
-    OriMon = [#erl_monitor{type = ?MON_ORIGIN,
+    MonType = case node(From) == node(To) of
+                  true -> process;
+                  false -> dist_process
+              end,
+
+    OriMon = [#erl_monitor{type = MonType,
+                           dir = origin,
                            ref = Ref,
                            pid = To}],
 
     OriMon = find_erl_monitor(From, Ref), 
 
-    TargMon = [#erl_monitor{type = ?MON_TARGET,
+    TargMon = [#erl_monitor{type = MonType,
+                            dir = target,
                             ref = Ref,
                             pid = From}],
     TargMon = find_erl_monitor(To, Ref),
@@ -915,7 +934,11 @@ check_process_monitor(From, To, Ref) when is_pid(From),
 
     case node(From) == node(To) of
         false ->
-            TargMon = find_erl_monitor({node(From), node(To)}, Ref),
+            DistTargMon = [#erl_monitor{type = dist_process,
+                                        dir = target,
+                                        ref = Ref,
+                                        pid = From}],
+            DistTargMon = find_erl_monitor({node(From), node(To)}, Ref),
             OriMon = find_erl_monitor({node(To), node(From)}, Ref);
         true ->
             [] = find_erl_monitor({node(From), node(From)}, Ref)
@@ -986,19 +1009,36 @@ check_process_demonitor(From, To, Ref) when is_pid(From),
     ok.
 
 no_of_monitor_node(From, Node) when is_pid(From), is_atom(Node) ->
-    length(find_erl_link(From, ?LINK_NODE, Node)).
+    case find_erl_monitor(From, Node) of
+        [] -> 0;
+        [#erl_monitor{type = node,
+                      dir = origin,
+                      pid = Node,
+                      extra = N}] -> N
+    end.
 
+check_monitor_node(From, Node, 0) when is_pid(From),
+                                        is_atom(Node) ->
+    [] = find_erl_monitor(From, Node),
+    [] = find_erl_monitor({node(From), Node}, From);
 check_monitor_node(From, Node, No) when is_pid(From),
                                         is_atom(Node),
                                         is_integer(No),
-                                        No >= 0 ->
-    LL = lists:duplicate(No, #erl_link{type = ?LINK_NODE, pid = Node}),
-    DLL = lists:duplicate(No, #erl_link{type = ?LINK_NODE, pid = From}),
-    LL = find_erl_link(From, ?LINK_NODE, Node),
-    DLL = find_erl_link({node(From), Node}, ?LINK_NODE, From),
-    ok.
-
-
+                                        No > 0 ->
+    [#erl_monitor{type = node,
+                  dir = origin,
+                  pid = Node,
+                  extra = No}] = find_erl_monitor(From, Node),
+    [#erl_monitor{type = node,
+                  dir = target,
+                  pid = From}] = find_erl_monitor({node(From), Node}, From).
+
+connection_id(Node) ->
+    try
+        erts_debug:get_internal_state({connection_id, Node})
+    catch
+        _:_ -> -1
+    end.
 
 hostname() ->
     from($@, atom_to_list(node())).
diff --git a/erts/emulator/test/monitor_SUITE.erl b/erts/emulator/test/monitor_SUITE.erl
index 9d772480d9..c7250a9d26 100644
--- a/erts/emulator/test/monitor_SUITE.erl
+++ b/erts/emulator/test/monitor_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 1999-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1999-2018. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -86,7 +86,7 @@ case_2(Config) when is_list(Config) ->
     R = erlang:monitor(process, B),
     B ! R,
     receive
-        {'EXIT', _} -> ok;
+        true -> ok;
         Other ->
             ct:fail({rec, Other})
     end,
@@ -98,7 +98,7 @@ case_2a(Config) when is_list(Config) ->
     {B,R} = spawn_monitor(?MODULE, y2, [self()]),
     B ! R,
     receive
-        {'EXIT', _} -> ok;
+        true -> ok;
         Other ->
             ct:fail({rec, Other})
     end,
@@ -182,7 +182,7 @@ demon_e_1(Config) when is_list(Config) ->
            end ),
     receive 
         {P2, ref, R2} -> 
-            demon_error(R2, badarg),
+            true = erlang:demonitor(R2),
             P2 ! {self(), stop};
         Other2 ->
             ct:fail({rec, Other2})
@@ -729,8 +729,8 @@ named_down(Config) when is_list(Config) ->
                            end),
     ?assertEqual(true, register(Name, NamedProc)),
     unlink(NamedProc),
-    exit(NamedProc, bang),
     Mon = erlang:monitor(process, Name),
+    exit(NamedProc, bang),
     receive {'DOWN',Mon, _, _, bang} -> ok
     after 3000 -> ?assert(false) end,
     ?assertEqual(true, register(Name, self())),
diff --git a/erts/emulator/test/port_SUITE.erl b/erts/emulator/test/port_SUITE.erl
index e46665a881..5b39d05df8 100644
--- a/erts/emulator/test/port_SUITE.erl
+++ b/erts/emulator/test/port_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -109,7 +109,6 @@
     mon_port_pid_demonitor/1,
     mon_port_remote_on_remote/1,
     mon_port_driver_die/1,
-    mon_port_driver_die_demonitor/1,
     mul_basic/1,
     mul_slow_writes/1,
     name1/1,
@@ -180,8 +179,7 @@ all() ->
      mon_port_bad_named,
      mon_port_pid_demonitor,
      mon_port_name_demonitor,
-     mon_port_driver_die,
-     mon_port_driver_die_demonitor
+     mon_port_driver_die
     ].
 
 groups() ->
@@ -2783,7 +2781,7 @@ mon_port_driver_die(Config) ->
     end,
     ok.
 
-
+-ifdef(DISABLED_TESTCASE).
 %% 1. Spawn a port which will sleep 3 seconds
 %% 2. Monitor port
 %% 3. Port driver and dies horribly (via C driver_failure call). This should
@@ -2819,6 +2817,7 @@ mon_port_driver_die_demonitor(Config) ->
     after 5000 -> ?assert(false)
     end,
     ok.
+-endif.
 
 %% @doc Makes a controllable port for testing. Underlying mechanism of this
 %% port is not important, only important is our ability to close/kill it or
diff --git a/erts/emulator/test/port_trace_SUITE.erl b/erts/emulator/test/port_trace_SUITE.erl
index a1986397a8..eba8f194e0 100644
--- a/erts/emulator/test/port_trace_SUITE.erl
+++ b/erts/emulator/test/port_trace_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1999-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1999-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -202,8 +202,7 @@ ports(_Config) ->
     erlang:port_close(Prt),
 
     [{trace,Prt,closed,normal},
-     {trace,Prt,unregister,port_trace_SUITE},
-     {trace,Prt,unlink,S}] = flush(),
+     {trace,Prt,unregister,port_trace_SUITE}] = flush(),
 
     ok.
 
@@ -475,8 +474,7 @@ failure_test(Failure, Reason) ->
         process_flag(trap_exit, false)
     end,
     [{trace, Prt, 'receive', {S, {command, Failure}}},
-     {trace, Prt, closed, Reason},
-     {trace, Prt, unlink, S}] = flush(),
+     {trace, Prt, closed, Reason}] = flush(),
 
     ok.
 
@@ -599,13 +597,11 @@ close(Prt, Flags) ->
 
     if Recv, Ports ->
             [{trace, Prt, 'receive', {S, close}},
-             {trace, Prt, closed, normal},
-             {trace, Prt, unlink, S}] = flush();
+             {trace, Prt, closed, normal}] = flush();
        Recv ->
             [{trace, Prt, 'receive', {S, close}}] = flush();
        Ports ->
-            [{trace, Prt, closed, normal},
-             {trace, Prt, unlink, S}] = flush();
+            [{trace, Prt, closed, normal}] = flush();
        true ->
             [] = flush()
     end.
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index a8bcfac84d..7eff786e8b 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -43,7 +43,6 @@
 	 process_info_lock_reschedule3/1,
          process_info_garbage_collection/1,
 	 bump_reductions/1, low_prio/1, binary_owner/1, yield/1, yield2/1,
-	 process_status_exiting/1,
 	 otp_4725/1, bad_register/1, garbage_collect/1, otp_6237/1,
 	 process_info_messages/1, process_flag_badarg/1, process_flag_heap_size/1,
 	 spawn_opt_heap_size/1, spawn_opt_max_heap_size/1,
@@ -80,7 +79,6 @@ all() ->
      process_info_lock_reschedule2,
      process_info_lock_reschedule3,
      process_info_garbage_collection,
-     process_status_exiting,
      bump_reductions, low_prio, yield, yield2, otp_4725,
      bad_register, garbage_collect, process_info_messages,
      process_flag_badarg, process_flag_heap_size,
@@ -841,28 +839,6 @@ process_info_lock_reschedule3(Config) when is_list(Config) ->
 		  ct:fail(BadStatus)
 	  end.
 
-process_status_exiting(Config) when is_list(Config) ->
-    %% Make sure that erts_debug:get_internal_state({process_status,P})
-    %% returns exiting if it is in status P_EXITING.
-    erts_debug:set_internal_state(available_internal_state,true),
-    Prio = process_flag(priority, max),
-    P = spawn_opt(fun () -> receive after infinity -> ok end end,
-			[{priority, normal}]),
-    erlang:yield(),
-    %% The tok_loop processes are here to make it hard for the exiting
-    %% process to be scheduled in for exit...
-    TokLoops = lists:map(fun (_) ->
-		spawn_opt(fun tok_loop/0,
-		    [link,{priority, high}])
-	end, lists:seq(1, erlang:system_info(schedulers_online))),
-    exit(P, boom),
-    wait_until(fun() ->
-		exiting =:= erts_debug:get_internal_state({process_status,P})
-	end),
-    lists:foreach(fun (Tok) -> unlink(Tok), exit(Tok,bang) end, TokLoops),
-    process_flag(priority, Prio),
-    ok.
-
 otp_4725(Config) when is_list(Config) ->
     Tester = self(),
     Ref1 = make_ref(),
@@ -1000,7 +976,7 @@ gv(Key,List) ->
 %% Tests erlang:bump_reductions/1.
 bump_reductions(Config) when is_list(Config) ->
     erlang:garbage_collect(),
-    receive after 1 -> ok end,		% Clear reductions.
+    erlang:yield(),		% Clear reductions.
     {reductions,R1} = process_info(self(), reductions),
     true = erlang:bump_reductions(100),
     {reductions,R2} = process_info(self(), reductions),
diff --git a/erts/emulator/test/signal_SUITE.erl b/erts/emulator/test/signal_SUITE.erl
index 61a8617165..fab2f45f28 100644
--- a/erts/emulator/test/signal_SUITE.erl
+++ b/erts/emulator/test/signal_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %% 
-%% Copyright Ericsson AB 2006-2017. All Rights Reserved.
+%% Copyright Ericsson AB 2006-2018. All Rights Reserved.
 %% 
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -34,23 +34,9 @@
 -export([init_per_testcase/2, end_per_testcase/2]).
 
 % Test cases
--export([xm_sig_order/1,
-	 pending_exit_unlink_process/1,
-	 pending_exit_unlink_dist_process/1,
-	 pending_exit_unlink_port/1,
-	 pending_exit_trap_exit/1,
-	 pending_exit_receive/1,
-	 pending_exit_exit/1,
-	 pending_exit_gc/1,
-	 pending_exit_is_process_alive/1,
-	 pending_exit_process_display/1,
-	 pending_exit_process_info_1/1,
-	 pending_exit_process_info_2/1,
-	 pending_exit_group_leader/1,
-	 exit_before_pending_exit/1]).
+-export([xm_sig_order/1]).
 
 init_per_testcase(Func, Config) when is_atom(Func), is_list(Config) ->
-    available_internal_state(true),
     [{testcase, Func}|Config].
 
 end_per_testcase(_Func, _Config) ->
@@ -60,24 +46,14 @@ init_per_suite(Config) ->
     Config.
 
 end_per_suite(_Config) ->
-    available_internal_state(true),
-    catch erts_debug:set_internal_state(not_running_optimization, true),
-    available_internal_state(false).
+    ok.
 
 suite() ->
     [{ct_hooks,[ts_install_cth]},
      {timetrap, {minutes, 2}}].
 
 all() -> 
-    [xm_sig_order, pending_exit_unlink_process,
-     pending_exit_unlink_dist_process,
-     pending_exit_unlink_port, pending_exit_trap_exit,
-     pending_exit_receive, pending_exit_trap_exit,
-     pending_exit_gc, pending_exit_is_process_alive,
-     pending_exit_process_display,
-     pending_exit_process_info_1,
-     pending_exit_process_info_2, pending_exit_group_leader,
-     exit_before_pending_exit].
+    [xm_sig_order].
 
 
 %% Test that exit signals and messages are received in correct order
@@ -113,362 +89,9 @@ xm_sig_order_proc() ->
     end,
     xm_sig_order_proc().
 
-pending_exit_unlink_process(Config) when is_list(Config) ->
-    pending_exit_test(self(), unlink).
-
-pending_exit_unlink_dist_process(Config) when is_list(Config) ->
-    {ok, Node} = start_node(Config),
-    From = spawn(Node, fun () -> receive after infinity -> ok end end),
-    Res = pending_exit_test(From, unlink),
-    stop_node(Node),
-    Res.
-
-pending_exit_unlink_port(Config) when is_list(Config) ->
-    pending_exit_test(hd(erlang:ports()), unlink).
-
-pending_exit_trap_exit(Config) when is_list(Config) ->
-    pending_exit_test(self(), trap_exit).
-
-pending_exit_receive(Config) when is_list(Config) ->
-    pending_exit_test(self(), 'receive').
-
-pending_exit_exit(Config) when is_list(Config) ->
-    pending_exit_test(self(), exit).
-
-pending_exit_gc(Config) when is_list(Config) ->
-    pending_exit_test(self(), gc).
-
-pending_exit_test(From, Type) ->
-    OTE = process_flag(trap_exit, true),
-    Ref = make_ref(),
-    Master = self(),
-    ExitBySignal = case Type of
-                       gc ->
-                           lists:duplicate(10000,
-                                           exit_by_signal);
-                       _ ->
-                           exit_by_signal
-                   end,
-    Pid = spawn_link(
-            fun () ->
-                    receive go -> ok end,
-                    false = have_pending_exit(),
-                    exit = fake_exit(From,
-                                     self(),
-                                     ExitBySignal),
-                    true = have_pending_exit(),
-                    Master ! {self(), Ref, Type},
-                    case Type of
-                        gc ->
-                            force_gc(),
-                            erlang:yield();
-                        unlink ->
-                            unlink(From);
-                        trap_exit ->
-                            process_flag(trap_exit, true);
-                        'receive' ->
-                            receive _ -> ok
-                            after 0 -> ok
-                            end;
-                        exit ->
-                            ok
-                    end,
-                    exit(exit_by_myself)
-            end),
-    Mon = erlang:monitor(process, Pid),
-    Pid ! go,
-    Reason = receive
-                 {'DOWN', Mon, process, Pid, R} ->
-                     receive
-                         {Pid, Ref, Type} ->
-                             ok
-                     after 0 ->
-                             ct:fail(premature_exit)
-                     end,
-                     case Type of
-                         exit ->
-                             exit_by_myself = R;
-                         _ ->
-                             ExitBySignal = R
-                     end
-             end,
-    receive
-        {'EXIT', Pid, R2} ->
-            Reason = R2
-    end,
-    process_flag(trap_exit, OTE),
-    ok,
-    {comment, "Test only valid with current SMP emulator."}.
-
-
-
-exit_before_pending_exit(Config) when is_list(Config) ->
-    %% This is a testcase testcase very specific to the smp
-    %% implementation as it is of the time of writing.
-    %%
-    %% The testcase tries to check that a process can
-    %% exit by itself even though it has a pending exit.
-    OTE = process_flag(trap_exit, true),
-    Master = self(),
-    Tester = spawn_link(
-               fun () ->
-                       Opts = case {erlang:system_info(run_queues),
-                                    erlang:system_info(schedulers_online)} of
-                                  {RQ, SO} when RQ =:= 1; SO =:= 1 -> [];
-                                  _ ->
-                                      process_flag(scheduler, 1),
-                                      [{scheduler, 2}]
-                              end,
-                       P = self(),
-                       Exiter = spawn_opt(fun () ->
-                                                  receive
-                                                      {exit_me, P, R} ->
-                                                          exit(P, R)
-                                                  end
-                                          end, Opts),
-                       erlang:yield(),
-                       Exiter ! {exit_me, self(), exited_by_exiter},
-                       %% We want to get a pending exit
-                       %% before we exit ourselves. We
-                       %% don't want to be scheduled out
-                       %% since we will then see the
-                       %% pending exit.
-                       %%
-                       %% Do something that takes
-                       %% relatively long time but
-                       %% consumes few reductions...
-                       repeat(fun() -> erlang:system_info(procs) end,10),
-                       %% ... then exit.
-                       Master ! {self(),
-                                 pending_exit,
-                                 have_pending_exit()},
-                       exit(exited_by_myself)
-               end),
-    PendingExit = receive {Tester, pending_exit, PE} -> PE end,
-    receive
-	      {'EXIT', Tester, exited_by_myself} ->
-		  process_flag(trap_exit, OTE),
-		  ok;
-	      Msg ->
-		  ct:fail({unexpected_message, Msg})
-	  end,
-    NoScheds = integer_to_list(erlang:system_info(schedulers_online)),
-    {comment,
-     "Was "
-     ++ case PendingExit of
-	    true -> "";
-	    false ->"*not*"
-	end ++ " able to trigger a pending exit. "
-     ++ "Running on " ++ NoScheds ++ " scheduler(s). "
-     ++ "This test is only interesting with at least two schedulers."}.
-
--define(PE_INFO_REPEAT, 100).
-
-pending_exit_is_process_alive(Config) when is_list(Config) ->
-    S = exit_op_test_init(),
-    TestFun = fun (P) -> false = is_process_alive(P) end,
-    repeated_exit_op_test(TestFun, ?PE_INFO_REPEAT),
-    verify_pending_exit_success(S),
-    comment().
-
-pending_exit_process_info_1(Config) when is_list(Config) ->
-    S = exit_op_test_init(),
-    TestFun = fun (P) ->
-			    undefined = process_info(P)
-		    end,
-    repeated_exit_op_test(TestFun, ?PE_INFO_REPEAT),
-    verify_pending_exit_success(S),
-    comment().
-
-pending_exit_process_info_2(Config) when is_list(Config) ->
-    S0 = exit_op_test_init(),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, messages)
-				end, ?PE_INFO_REPEAT),
-    S1 = verify_pending_exit_success(S0),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, status)
-				end, ?PE_INFO_REPEAT),
-    S2 = verify_pending_exit_success(S1),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, links)
-				end, ?PE_INFO_REPEAT),
-    S3 = verify_pending_exit_success(S2),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [messages])
-				end, ?PE_INFO_REPEAT),
-    S4 = verify_pending_exit_success(S3),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [status])
-				end, ?PE_INFO_REPEAT),
-    S5 = verify_pending_exit_success(S4),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [links])
-				end, ?PE_INFO_REPEAT),
-    S6 = verify_pending_exit_success(S5),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [status,
-								     links])
-				end, ?PE_INFO_REPEAT),
-    S7 = verify_pending_exit_success(S6),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [messages,
-								     status])
-				end, ?PE_INFO_REPEAT),
-    S8 = verify_pending_exit_success(S7),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [messages,
-								     links])
-				end, ?PE_INFO_REPEAT),
-    S9 = verify_pending_exit_success(S8),
-    repeated_exit_op_test(
-	    fun (P) ->
-		    undefined = process_info(P, [message_queue_len,
-						 status])
-	    end, ?PE_INFO_REPEAT),
-    S10 = verify_pending_exit_success(S9),
-    repeated_exit_op_test(fun (P) ->
-					undefined = process_info(P, [messages,
-								     links,
-								     status])
-				end, ?PE_INFO_REPEAT),
-    verify_pending_exit_success(S10),
-    comment().
-
-pending_exit_process_display(Config) when is_list(Config) ->
-    S = exit_op_test_init(),
-    TestFun = fun (P) ->
-			    badarg = try
-					 erlang:process_display(P, backtrace)
-				     catch
-					 error:badarg -> badarg
-				     end
-		    end,
-    repeated_exit_op_test(TestFun, ?PE_INFO_REPEAT),
-    verify_pending_exit_success(S),
-    comment().
-
-pending_exit_group_leader(Config) when is_list(Config) ->
-    S = exit_op_test_init(),
-    TestFun = fun (P) ->
-			    badarg = try
-					 group_leader(self(), P)
-				     catch
-					 error:badarg -> badarg
-				     end
-		    end,
-    repeated_exit_op_test(TestFun, ?PE_INFO_REPEAT),
-    verify_pending_exit_success(S),
-    comment().
-
 %%
 %% -- Internal utils --------------------------------------------------------
 %%
-exit_op_test_init() ->
-    put(no_pending_exit_success, 0),
-    put(no_pending_exit_tries, 0),
-    {case {erlang:system_info(run_queues),
-	   erlang:system_info(schedulers_online)} of
-	 {RQ, SO} when RQ =:= 1; SO =:= 1 -> false;
-	 _ -> true
-     end, 0, 0}.
-
-verify_pending_exit_success({false, _, _} = S) ->
-    S;
-verify_pending_exit_success({true, S, T}) ->
-    NewS = get(no_pending_exit_success),
-    NewT = get(no_pending_exit_tries),
-    case NewT =:= T of
-	true -> ok;
-	_ -> case NewS > S of
-		 true -> ok;
-		 _ -> exit(no_pending_exits)
-	     end
-    end,
-    {true, NewS, NewT}.
-
-comment() ->
-    {comment,
-     "Pending exit trigger ratio "
-     ++ integer_to_list(get(no_pending_exit_success))
-     ++ "/"
-     ++ integer_to_list(get(no_pending_exit_tries))
-     ++ "."
-     ++ case get(not_running_opt_test) of
-	    true -> " No 'not running optimization' to disable.";
-	    _ -> ""
-	end}.
-
-repeated_exit_op_test(TestFun, N) ->
-    WorkFun0 = fun () ->
-		       lists:sort(lists:reverse(lists:seq(1, 1000)))
-	       end,
-    repeat(fun () -> exit_op_test(TestFun, WorkFun0) end, N),
-    try erts_debug:set_internal_state(not_running_optimization, false) of
-	Bool when Bool == true; Bool == false -> 
-	    WorkFun1 = fun () ->
-			       erts_debug:set_internal_state(sleep, 0),
-			       lists:sort(lists:reverse(lists:seq(1, 1000)))
-			    end,
-	    repeat(fun () ->
-			   exit_op_test(TestFun, WorkFun1)
-		   end, N)
-    catch
-	error:notsup -> put(not_running_opt_test, true)
-    after
-	catch erts_debug:set_internal_state(not_running_optimization, true)
-    end.
-
-exit_op_test(TestFun, WorkFun) ->
-    Opts = case {erlang:system_info(run_queues),
-		 erlang:system_info(schedulers_online)} of
-	       {RQ, SO} when RQ =:= 1; SO =:= 1 -> [];
-	       _ ->
-		   process_flag(scheduler, 1),
-		   [{scheduler, 2}]
-	   end,
-    Master = self(),
-    Going = make_ref(),
-    P = spawn_opt(fun () ->
-			  loop(10, WorkFun),
-			  Master ! Going,
-			  loop(infinity, WorkFun)
-		  end, Opts),
-    receive Going -> ok end,
-    loop(10, WorkFun),
-    erlang:yield(),
-    exit(P, bang),
-    PE0 = have_pending_exit(P),
-    TestFun(P),
-    PE = case PE0 of
-	     true -> true;
-	     _ -> false
-	 end,
-    case {PE, get(no_pending_exit_success), get(no_pending_exit_tries)} of
-	{true, undefined, undefined} ->
-	    put(no_pending_exit_success, 1),
-	    put(no_pending_exit_tries, 1);
-	{false, undefined, undefined} ->
-	    put(no_pending_exit_success, 0),
-	    put(no_pending_exit_tries, 1);
-	{true, S, T} ->
-	    put(no_pending_exit_success, S+1),
-	    put(no_pending_exit_tries, T+1);
-	{false, _S, T} ->
-	    put(no_pending_exit_tries, T+1)
-    end,
-    ok.
-
-loop(infinity, WorkFun) ->
-    do_loop(infinity, WorkFun);
-loop(0, _WorkFun) ->
-    ok;
-loop(N, WorkFun) when is_integer(N) ->
-    do_loop(N-1, WorkFun).
-
-do_loop(N, WorkFun) ->
-    WorkFun(),
-    loop(N, WorkFun).
 
 repeat(_Fun, N) when is_integer(N), N =< 0 ->
     ok;
@@ -486,30 +109,3 @@ start_node(Config) ->
 
 stop_node(Node) ->
     test_server:stop_node(Node).
-
-have_pending_exit() ->
-    have_pending_exit(self()).
-
-have_pending_exit(Pid) ->
-    erts_debug:get_internal_state({have_pending_exit, Pid}).
-
-force_gc() ->
-    erts_debug:set_internal_state(force_gc, self()).
-
-fake_exit(From, To, Reason) ->
-    erts_debug:set_internal_state(send_fake_exit_signal, {From, To, Reason}).
-
-available_internal_state(Bool) when Bool == true; Bool == false ->
-    case {Bool,
-          (catch erts_debug:get_internal_state(available_internal_state))} of
-        {true, true} ->
-            true;
-        {false, true} ->
-            erts_debug:set_internal_state(available_internal_state, false),
-            true;
-        {true, _} ->
-            erts_debug:set_internal_state(available_internal_state, true),
-            false;
-        {false, _} ->
-            false
-    end.
diff --git a/erts/emulator/test/trace_SUITE.erl b/erts/emulator/test/trace_SUITE.erl
index a81aa64057..def25dba7d 100644
--- a/erts/emulator/test/trace_SUITE.erl
+++ b/erts/emulator/test/trace_SUITE.erl
@@ -1,7 +1,7 @@
 %%
 %% %CopyrightBegin%
 %%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
 %%
 %% Licensed under the Apache License, Version 2.0 (the "License");
 %% you may not use this file except in compliance with the License.
@@ -235,7 +235,7 @@ link_receive_call_correlation(Config) when is_list(Config) ->
     1 = erlang:trace(Receiver, true, ['receive', procs, call, timestamp, scheduler_id]),
     1 = erlang:trace_pattern({?MODULE, receive_msg, '_'}, [], [local]),
 
-    Num = 100000,
+    Num = 100,
 
     (fun F(0) -> [];
          F(N) ->
@@ -255,7 +255,7 @@ link_receive_call_correlation(Config) when is_list(Config) ->
 
     Msgs = (fun F() -> receive M -> [M | F()] after 1 -> [] end end)(),
 
-    case check_consistent(Receiver, Num, Num, Num, Msgs) of
+    case check_consistent(Receiver, Num, Num, Num, Msgs, false, undefined) of
         ok ->
             ok;
         {error, Reason} ->
@@ -265,20 +265,63 @@ link_receive_call_correlation(Config) when is_list(Config) ->
 
 -define(schedid, , _).
 
-check_consistent(_Pid, Recv, Call, _LU, [Msg | _]) when Recv > Call ->
+check_consistent(_Pid, Recv, Call, _LU, [Msg | _], _Received, _LinkedN) when Recv > Call ->
     {error, Msg};
-check_consistent(Pid, Recv, Call, LU, [Msg | Msgs]) ->
+check_consistent(Pid, Recv, Call, LU, [Msg | Msgs], false, undefined) ->
 
     case Msg of
         {trace, Pid, 'receive', Recv ?schedid} ->
-            check_consistent(Pid,Recv - 1, Call, LU, Msgs);
+            check_consistent(Pid,Recv - 1, Call, LU, Msgs, true, undefined);
         {trace_ts, Pid, 'receive', Recv ?schedid, _} ->
-            check_consistent(Pid,Recv - 1, Call, LU, Msgs);
+            check_consistent(Pid,Recv - 1, Call, LU, Msgs, true, undefined);
 
         {trace, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid} ->
-            check_consistent(Pid,Recv, Call - 1, LU, Msgs);
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, false, undefined);
         {trace_ts, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid, _} ->
-            check_consistent(Pid,Recv, Call - 1, LU, Msgs);
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, false, undefined);
+
+        {trace, Pid, _, _Self ?schedid} ->
+            check_consistent(Pid, Recv, Call, LU, Msgs, false, undefined);
+        {trace_ts, Pid, _, _Self ?schedid, _} ->
+            check_consistent(Pid, Recv, Call, LU, Msgs, false, undefined);
+
+        Msg ->
+            {error, Msg}
+    end;
+check_consistent(Pid, Recv, Call, LU, [Msg | Msgs], true, undefined) ->
+
+    case Msg of
+        {trace, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid} ->
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, true, undefined);
+        {trace_ts, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid, _} ->
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, true, undefined);
+
+        {trace, Pid, getting_linked, _Self ?schedid} ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, Recv rem 2);
+        {trace_ts, Pid, getting_linked, _Self ?schedid, _} ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, Recv rem 2);
+
+        {trace, Pid, getting_unlinked, _Self ?schedid} ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, (Recv+1) rem 2);
+        {trace_ts, Pid, getting_unlinked, _Self ?schedid, _} ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, (Recv+1) rem 2);
+
+        Msg ->
+            {error, Msg}
+    end;
+check_consistent(Pid, Recv, Call, LU, [Msg | Msgs], true, LinkedN) ->
+    UnlinkedN = (LinkedN + 1) rem 2,
+
+    case Msg of
+        {trace, Pid, 'receive', Recv ?schedid} when Recv == LU ->
+            check_consistent(Pid,Recv - 1, Call, LU, Msgs, true, LinkedN);
+        {trace_ts, Pid, 'receive', Recv ?schedid, _} when Recv == LU ->
+            check_consistent(Pid,Recv - 1, Call, LU, Msgs, true, LinkedN);
+
+        {trace, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid} ->
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, true, LinkedN);
+        {trace_ts, Pid, call, {?MODULE, receive_msg, [Call]} ?schedid, _} ->
+            check_consistent(Pid,Recv, Call - 1, LU, Msgs, true, LinkedN);
 
         %% We check that for each receive we have gotten a
         %% getting_linked or getting_unlinked message. Also
@@ -286,38 +329,38 @@ check_consistent(Pid, Recv, Call, LU, [Msg | Msgs]) ->
         %% message we expect to receive is an even number
         %% and odd number for getting_unlinked.
         {trace, Pid, getting_linked, _Self ?schedid}
-          when Recv rem 2 == 0, Recv == LU ->
-            check_consistent(Pid, Recv, Call, LU - 1, Msgs);
+          when Recv rem 2 == LinkedN ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, LinkedN);
         {trace_ts, Pid, getting_linked, _Self ?schedid, _}
-          when Recv rem 2 == 0, Recv == LU ->
-            check_consistent(Pid, Recv, Call, LU - 1, Msgs);
+          when Recv rem 2 == LinkedN ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, LinkedN);
 
         {trace, Pid, getting_unlinked, _Self ?schedid}
-          when Recv rem 2 == 1, Recv == LU ->
-            check_consistent(Pid, Recv, Call, LU - 1, Msgs);
+          when Recv rem 2 == UnlinkedN ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, LinkedN);
         {trace_ts, Pid, getting_unlinked, _Self ?schedid, _}
-          when Recv rem 2 == 1, Recv == LU ->
-            check_consistent(Pid, Recv, Call, LU - 1, Msgs);
+          when Recv rem 2 == UnlinkedN ->
+            check_consistent(Pid, Recv, Call, LU - 1, Msgs, true, LinkedN);
 
         {trace,Pid,'receive',Ignore ?schedid}
           when Ignore == stop; Ignore == timeout ->
-            check_consistent(Pid, Recv, Call, LU, Msgs);
+            check_consistent(Pid, Recv, Call, LU, Msgs, true, LinkedN);
         {trace_ts,Pid,'receive',Ignore ?schedid,_}
           when Ignore == stop; Ignore == timeout ->
-            check_consistent(Pid, Recv, Call, LU, Msgs);
+            check_consistent(Pid, Recv, Call, LU, Msgs, true, LinkedN);
 
         {trace, Pid, exit, normal ?schedid} ->
-            check_consistent(Pid, Recv, Call, LU, Msgs);
+            check_consistent(Pid, Recv, Call, LU, Msgs, true, LinkedN);
         {trace_ts, Pid, exit, normal  ?schedid, _} ->
-            check_consistent(Pid, Recv, Call, LU, Msgs);
+            check_consistent(Pid, Recv, Call, LU, Msgs, true, LinkedN);
         {'EXIT', Pid, normal} ->
-            check_consistent(Pid, Recv, Call, LU, Msgs);
+            check_consistent(Pid, Recv, Call, LU, Msgs, true, LinkedN);
         Msg ->
             {error, Msg}
     end;
-check_consistent(_, 0, 0, 0, []) ->
+check_consistent(_, 0, 0, 1, [], true, _) ->
     ok;
-check_consistent(_, Recv, Call, LU, []) ->
+check_consistent(_, Recv, Call, LU, [], _, _) ->
     {error,{Recv, Call, LU}}.
 
 receive_msg(M) ->