File 4031-erts-Improve-flushing-of-signals.patch of Package erlang

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File 4031-erts-Improve-flushing-of-signals.patch of Package erlang (Revision 01b3dc6452ffd94552aa8e1bbc0ff8ba)

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From ac579bbec058b313af19de4a6d536c6ab446bfed Mon Sep 17 00:00:00 2001
From: Rickard Green <rickard@erlang.org>
Date: Tue, 11 May 2021 19:17:32 +0200
Subject: [PATCH 1/2] [erts] Improve flushing of signals

---
 erts/emulator/beam/bif.c                |  75 ++++----
 erts/emulator/beam/bif.h                |  10 +-
 erts/emulator/beam/erl_bif_info.c       | 221 +++++++++++++++++-------
 erts/emulator/beam/erl_bif_port.c       |  89 ++++++++--
 erts/emulator/beam/erl_message.c        |   6 +
 erts/emulator/beam/erl_proc_sig_queue.c | 181 +++++++++++++++++--
 erts/emulator/beam/erl_proc_sig_queue.h |  70 +++++++-
 erts/emulator/beam/erl_process.c        |  62 ++++---
 erts/emulator/beam/erl_process.h        |   9 +-
 erts/emulator/beam/erl_process_dump.c   |  17 +-
 erts/emulator/test/bif_SUITE.erl        |  60 ++++++-
 erts/emulator/test/nif_SUITE.erl        |   5 +-
 erts/emulator/test/port_SUITE.erl       |   1 +
 erts/emulator/test/process_SUITE.erl    | 178 +++++++++++++++++--
 erts/etc/unix/etp-commands.in           |   2 +-
 15 files changed, 793 insertions(+), 193 deletions(-)

diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index a30d6b6a9e..87241e6dce 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -1524,7 +1524,7 @@ erts_internal_await_exit_trap(BIF_ALIST_0)
      * terminated in order to ensure that signal order
      * is preserved. Yield if necessary.
      */
-    erts_aint32_t state;
+    erts_aint32_t state = erts_atomic32_read_nob(&BIF_P->state);
     int reds = ERTS_BIF_REDS_LEFT(BIF_P);
     (void) erts_proc_sig_handle_incoming(BIF_P, &state, &reds,
                                          reds, !0);
@@ -5395,45 +5395,52 @@ static BIF_RETTYPE bif_return_trap(BIF_ALIST_2)
 }
 
 static BIF_RETTYPE
-bif_handle_signals_return(BIF_ALIST_1)
+bif_handle_signals_return(BIF_ALIST_2)
 {
-    int local_only = BIF_P->sig_qs.flags & FS_LOCAL_SIGS_ONLY;
-    int sres, sreds, reds_left;
+    int reds_left;
     erts_aint32_t state;
 
-    reds_left = ERTS_BIF_REDS_LEFT(BIF_P);
-    sreds = reds_left;
-
-    if (!local_only) {
-        erts_proc_lock(BIF_P, ERTS_PROC_LOCK_MSGQ);
-        erts_proc_sig_fetch(BIF_P);
-        erts_proc_unlock(BIF_P, ERTS_PROC_LOCK_MSGQ);
+    if (BIF_P->sig_qs.flags & FS_FLUSHED_SIGS) {
+    flushed:
+	ASSERT(BIF_P->sig_qs.flags & FS_FLUSHING_SIGS);
+	BIF_P->sig_qs.flags &= ~(FS_FLUSHED_SIGS|FS_FLUSHING_SIGS);
+        erts_set_gc_state(BIF_P, !0); /* Allow GC again... */
+	BIF_RET(BIF_ARG_2);
     }
+    
+    if (!(BIF_P->sig_qs.flags & FS_FLUSHING_SIGS)) {
+        int flags = ((is_internal_pid(BIF_ARG_1)
+                      || is_internal_port(BIF_ARG_1))
+                     ? ERTS_PROC_SIG_FLUSH_FLG_FROM_ID
+                     : ERTS_PROC_SIG_FLUSH_FLG_FROM_ALL);
+	erts_proc_sig_init_flush_signals(BIF_P, flags, BIF_ARG_1);
+        if (BIF_P->sig_qs.flags & FS_FLUSHED_SIGS)
+            goto flushed;
+    }
+    
+    ASSERT(BIF_P->sig_qs.flags & FS_FLUSHING_SIGS);
 
-    state = erts_atomic32_read_nob(&BIF_P->state);
-    sres = erts_proc_sig_handle_incoming(BIF_P, &state, &sreds,
-                                         sreds, !0);
-
-    BUMP_REDS(BIF_P, (int) sreds);
-    reds_left -= sreds;
+    reds_left = ERTS_BIF_REDS_LEFT(BIF_P);
 
-    if (state & ERTS_PSFLG_EXITING) {
-        BIF_P->sig_qs.flags &= ~FS_LOCAL_SIGS_ONLY;
-        ERTS_BIF_EXITED(BIF_P);
-    }
-    if (!sres | (reds_left <= 0)) {
-        /*
-         * More signals to handle or out of reds; need
-         * to yield and continue. Prevent fetching of
-         * more signals by setting local-sigs-only flag.
-         */
-        BIF_P->sig_qs.flags |= FS_LOCAL_SIGS_ONLY;
-        ERTS_BIF_YIELD1(&erts_bif_handle_signals_return_export,
-                        BIF_P, BIF_ARG_1);
-    }
+    state = erts_atomic32_read_nob(&BIF_P->state);
+    do {
+	int sreds = reds_left;
+	(void) erts_proc_sig_handle_incoming(BIF_P, &state, &sreds,
+					     sreds, !0);
+	BUMP_REDS(BIF_P, (int) sreds);
+	if (state & ERTS_PSFLG_EXITING)
+	    ERTS_BIF_EXITED(BIF_P);
+	if (BIF_P->sig_qs.flags & FS_FLUSHED_SIGS)
+            goto flushed;
+	reds_left -= sreds;
+    } while (reds_left > 0);
 
-    BIF_P->sig_qs.flags &= ~FS_LOCAL_SIGS_ONLY;
-    BIF_RET(BIF_ARG_1);
+    /*
+     * More signals to handle, but out of reductions. Yield
+     * and come back here and continue...
+     */
+    ERTS_BIF_YIELD2(&erts_bif_handle_signals_return_export,
+		    BIF_P, BIF_ARG_1, BIF_ARG_2);
 }
 
 Export bif_return_trap_export;
@@ -5475,7 +5482,7 @@ void erts_init_bif(void)
 			  &bif_return_trap);
 
     erts_init_trap_export(&erts_bif_handle_signals_return_export,
-			  am_erlang, am_bif_handle_signals_return, 1,
+			  am_erlang, am_bif_handle_signals_return, 2,
 			  &bif_handle_signals_return);
 
     erts_await_result = erts_export_put(am_erts_internal,
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index 350f2ad430..a89ea5d4f2 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -522,12 +522,12 @@ do {									\
 
 extern Export erts_bif_handle_signals_return_export;
 
-#define ERTS_BIF_HANDLE_SIGNALS_RETURN(P, VAL)                          \
-    BIF_TRAP1(&erts_bif_handle_signals_return_export, (P), (VAL))
+#define ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(P, FROM, VAL)               \
+    BIF_TRAP2(&erts_bif_handle_signals_return_export, (P), (FROM), (VAL))
 
-#define ERTS_BIF_PREP_HANDLE_SIGNALS_RETURN(Ret, P, Val)                \
-    ERTS_BIF_PREP_TRAP1((Ret), &erts_bif_handle_signals_return_export,  \
-                        (P), (Val))
+#define ERTS_BIF_PREP_HANDLE_SIGNALS_FROM_RETURN(Ret, P, From, Val)     \
+    ERTS_BIF_PREP_TRAP2((Ret), &erts_bif_handle_signals_return_export,  \
+                        (P), (From), (Val))
 
 #define ERTS_BIF_PREP_EXITED(RET, PROC)	                                \
 do {                                                                    \
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 2c27d460fd..430c4f1d80 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -1007,6 +1007,7 @@ process_info_aux(Process *c_p,
 		 Process *rp,
 		 ErtsProcLocks rp_locks,
 		 int item_ix,
+                 Sint *msgq_len_p,
 		 int flags,
                  Uint *reserve_sizep,
                  Uint *reds);
@@ -1025,11 +1026,12 @@ erts_process_info(Process *c_p,
     Eterm res;
     Eterm part_res[ERTS_PI_ARGS];
     int item_ix_ix, ix;
+    Sint msgq_len = -1;
 
     if (ERTS_PI_FLAG_SINGELTON & flags) {
         ASSERT(item_ix_len == 1);
 	res = process_info_aux(c_p, hfact, rp, rp_locks, item_ix[0],
-                               flags, &reserve_size, reds);
+                               &msgq_len, flags, &reserve_size, reds);
         return res;
     }
 
@@ -1047,7 +1049,7 @@ erts_process_info(Process *c_p,
 	ix = pi_arg2ix(am_messages);
 	ASSERT(part_res[ix] == THE_NON_VALUE);
 	res = process_info_aux(c_p, hfact, rp, rp_locks, ix,
-                               flags, &reserve_size, reds);
+                               &msgq_len, flags, &reserve_size, reds);
 	ASSERT(res != am_undefined);
 	ASSERT(res != THE_NON_VALUE);
         part_res[ix] = res;
@@ -1057,7 +1059,7 @@ erts_process_info(Process *c_p,
 	ix = item_ix[item_ix_ix];
 	if (part_res[ix] == THE_NON_VALUE) {
 	    res = process_info_aux(c_p, hfact, rp, rp_locks, ix,
-                                   flags, &reserve_size, reds);
+                                   &msgq_len, flags, &reserve_size, reds);
             ASSERT(res != am_undefined);
 	    ASSERT(res != THE_NON_VALUE);
             part_res[ix] = res;
@@ -1092,6 +1094,92 @@ erts_process_info(Process *c_p,
 static void
 pi_setup_grow(int **arr, int *def_arr, Uint *sz, int ix);
 
+static ERTS_INLINE int
+pi_maybe_flush_signals(Process *c_p, int pi_flags)
+{
+    int reds_left;
+    erts_aint32_t state;
+
+    /*
+     * pi_maybe_flush_signals() flush signals in callers
+     * signal queue for two different reasons:
+     *
+     * 1. If we need 'message_queue_len', but not 'messages', we need
+     *    to handle all signals in the middle queue in order for
+     *    'c_p->sig_qs.len' to reflect the amount of messages in the
+     *    message queue. We could count traverse the queues, but it
+     *    is better to handle all signals in the queue instead since
+     *    this is work we anyway need to do at some point.
+     *
+     * 2. Ensures that all signals that the caller might have sent to
+     *    itself are handled before we gather information.
+     *
+     *    This is, however, not strictly necessary. process_info() is
+     *    not documented to send itself a signal when gathering
+     *    information about itself. That is, the operation is not
+     *    bound by the signal order guarantee when gathering
+     *    information about itself. If we do not handle outstanding
+     *    signals before gathering the information, outstanding signals
+     *    from the caller to itself will not be part of the result.
+     *    This would not be wrong, but perhaps surprising for the user.
+     *    We continue doing it this way for now, since this is how it
+     *    has been done for a very long time. We should, however,
+     *    consider changing this in a future release, since this signal
+     *    handling is not for free, although quite cheap since these
+     *    signals anyway must be handled at some point.
+     */
+
+    if (c_p->sig_qs.flags & FS_FLUSHED_SIGS) {
+    flushed:
+
+        ASSERT(((pi_flags & (ERTS_PI_FLAG_WANT_MSGS
+                             | ERTS_PI_FLAG_NEED_MSGQ_LEN))
+                != ERTS_PI_FLAG_NEED_MSGQ_LEN)
+               || !c_p->sig_qs.cont);
+	ASSERT(c_p->sig_qs.flags & FS_FLUSHING_SIGS);
+
+	c_p->sig_qs.flags &= ~(FS_FLUSHED_SIGS|FS_FLUSHING_SIGS);
+        erts_set_gc_state(c_p, !0); /* Allow GC again... */
+	return 0; /* done, all signals handled... */
+    }
+    
+    state = erts_atomic32_read_nob(&c_p->state);
+
+    if (!(c_p->sig_qs.flags & FS_FLUSHING_SIGS)) {
+        int flush_flags = 0;
+        if (((pi_flags & (ERTS_PI_FLAG_WANT_MSGS
+                          | ERTS_PI_FLAG_NEED_MSGQ_LEN))
+             == ERTS_PI_FLAG_NEED_MSGQ_LEN)
+            && c_p->sig_qs.cont) {
+            flush_flags |= ERTS_PROC_SIG_FLUSH_FLG_CLEAN_SIGQ;
+        }
+        if (state & ERTS_PSFLG_MAYBE_SELF_SIGS)
+            flush_flags |= ERTS_PROC_SIG_FLUSH_FLG_FROM_ID;
+	if (!flush_flags)
+	    return 0; /* done; no need to flush... */
+	erts_proc_sig_init_flush_signals(c_p, flush_flags, c_p->common.id);
+        if (c_p->sig_qs.flags & FS_FLUSHED_SIGS)
+            goto flushed;
+    }
+
+    ASSERT(c_p->sig_qs.flags & FS_FLUSHING_SIGS);
+    reds_left = ERTS_BIF_REDS_LEFT(c_p);
+
+    do {
+	int sreds = reds_left;
+	(void) erts_proc_sig_handle_incoming(c_p, &state, &sreds,
+					     sreds, !0);
+	BUMP_REDS(c_p, (int) sreds);
+	if (state & ERTS_PSFLG_EXITING)
+	    return -1; /* process exiting... */
+	if (c_p->sig_qs.flags & FS_FLUSHED_SIGS)
+            goto flushed;
+	reds_left -= sreds;
+    } while (reds_left > 0);
+
+    return 1; /* yield and continue here later... */
+}
+
 static BIF_RETTYPE
 process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
 {
@@ -1110,41 +1198,6 @@ process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
 
     ERTS_CT_ASSERT(ERTS_PI_DEF_ARR_SZ > 0);
 
-    if (c_p->common.id == pid) {
-        int local_only = c_p->sig_qs.flags & FS_LOCAL_SIGS_ONLY;
-        int sres, sreds, reds_left;
-
-        reds_left = ERTS_BIF_REDS_LEFT(c_p);
-        sreds = reds_left;
-
-        if (!local_only) {
-            erts_proc_sig_queue_lock(c_p);
-            erts_proc_sig_fetch(c_p);
-            erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
-        }
-
-        sres = erts_proc_sig_handle_incoming(c_p, &state, &sreds, sreds, !0);
-
-        BUMP_REDS(c_p, (int) sreds);
-        reds_left -= sreds;
-
-        if (state & ERTS_PSFLG_EXITING) {
-            c_p->sig_qs.flags &= ~FS_LOCAL_SIGS_ONLY;
-            goto exited;
-        }
-        if (!sres | (reds_left <= 0)) {
-            /*
-             * More signals to handle or out of reds; need
-             * to yield and continue. Prevent fetching of
-             * more signals by setting local-sigs-only flag.
-             */
-            c_p->sig_qs.flags |= FS_LOCAL_SIGS_ONLY;
-            goto yield;
-        }
-
-        c_p->sig_qs.flags &= ~FS_LOCAL_SIGS_ONLY;
-    }
-
     if (is_atom(opt)) {
 	int ix = pi_arg2ix(opt);
         item_ix[0] = ix;
@@ -1190,7 +1243,16 @@ process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
             goto badarg;
     }
 
-    if (is_not_internal_pid(pid)) {
+    if (c_p->common.id == pid) {
+        int res = pi_maybe_flush_signals(c_p, flags);
+	if (res != 0) {
+	    if (res > 0)
+		goto yield;
+	    else
+		goto exited;
+	}
+    }
+    else if (is_not_internal_pid(pid)) {
         if (is_external_pid(pid)
             && external_pid_dist_entry(pid) == erts_this_dist_entry)
             goto undefined;
@@ -1226,6 +1288,10 @@ process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
         }
         if (flags & ERTS_PI_FLAG_NEED_MSGQ_LEN) {
             ASSERT(locks & ERTS_PROC_LOCK_MAIN);
+            if (rp->sig_qs.flags & FS_FLUSHING_SIGS) {
+                erts_proc_unlock(rp, locks);
+                goto send_signal;
+            }
             erts_proc_sig_queue_lock(rp);
             erts_proc_sig_fetch(rp);
             if (rp->sig_qs.cont) {
@@ -1264,7 +1330,8 @@ process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
     if (c_p == rp || !ERTS_PROC_HAS_INCOMING_SIGNALS(c_p))
         ERTS_BIF_PREP_RET(ret, res);
     else
-        ERTS_BIF_PREP_HANDLE_SIGNALS_RETURN(ret, c_p, res);
+        ERTS_BIF_PREP_HANDLE_SIGNALS_FROM_RETURN(ret, c_p,
+                                                 pid, res);
 
 done:
 
@@ -1355,6 +1422,7 @@ process_info_aux(Process *c_p,
 		 Process *rp,
 		 ErtsProcLocks rp_locks,
 		 int item_ix,
+                 Sint *msgq_len_p,
 		 int flags,
                  Uint *reserve_sizep,
                  Uint *reds)
@@ -1468,8 +1536,10 @@ process_info_aux(Process *c_p,
 
     case ERTS_PI_IX_MESSAGES: {
         ASSERT(flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
-	if (rp->sig_qs.len == 0 || (ERTS_TRACE_FLAGS(rp) & F_SENSITIVE))
+	if (rp->sig_qs.len == 0 || (ERTS_TRACE_FLAGS(rp) & F_SENSITIVE)) {
+            *msgq_len_p = 0;
             res = NIL;
+        }
         else {
             int info_on_self = !(flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER);
 	    ErtsMessageInfo *mip;
@@ -1487,8 +1557,8 @@ process_info_aux(Process *c_p,
 	    heap_need = erts_proc_sig_prep_msgq_for_inspection(c_p, rp,
                                                                rp_locks,
                                                                info_on_self,
-                                                               mip);
-            len = rp->sig_qs.len;
+                                                               mip, msgq_len_p);
+            len = *msgq_len_p;
 
 	    heap_need += len*2; /* Cons cells */
 
@@ -1517,9 +1587,13 @@ process_info_aux(Process *c_p,
     }
 
     case ERTS_PI_IX_MESSAGE_QUEUE_LEN: {
-        Sint len = rp->sig_qs.len;
+        Sint len = *msgq_len_p;
+        if (len < 0) {
+            ASSERT((flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER)
+                   || !rp->sig_qs.cont);
+            len = rp->sig_qs.len;
+        }
         ASSERT(flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
-        ASSERT((flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER) || !rp->sig_qs.cont);
         ASSERT(len >= 0);
         if (len <= MAX_SMALL)
             res = make_small(len);
@@ -3690,42 +3764,54 @@ BIF_RETTYPE erts_internal_is_process_alive_2(BIF_ALIST_2)
         BIF_ERROR(BIF_P, BADARG);
     if (!erts_proc_sig_send_is_alive_request(BIF_P, BIF_ARG_1, BIF_ARG_2)) {
         if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P))
-            ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, am_ok);
+            ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, BIF_ARG_1, am_ok);
     }
     BIF_RET(am_ok);
 }
 
 BIF_RETTYPE is_process_alive_1(BIF_ALIST_1) 
 {
+
     if (is_internal_pid(BIF_ARG_1)) {
-        erts_aint32_t state;
+        BIF_RETTYPE result;
         Process *rp;
 
         if (BIF_ARG_1 == BIF_P->common.id)
             BIF_RET(am_true);
 
         rp = erts_proc_lookup_raw(BIF_ARG_1);
-        if (!rp)
-            BIF_RET(am_false);
+        if (!rp) {
+            result = am_false;
+        }
+        else {
+            erts_aint32_t state = erts_atomic32_read_acqb(&rp->state);
+            if (state & (ERTS_PSFLG_EXITING
+                         | ERTS_PSFLG_SIG_Q
+                         | ERTS_PSFLG_SIG_IN_Q)) {
+                /*
+                 * If in exiting state, trap out and send 'is alive'
+                 * request and wait for it to complete termination.
+                 *
+                 * If process has signals enqueued, we need to
+                 * send it an 'is alive' request via its signal
+                 * queue in order to ensure that signal order is
+                 * preserved (we may earlier have sent it an
+                 * exit signal that has not been processed yet).
+                 */
+                BIF_TRAP1(is_process_alive_trap, BIF_P, BIF_ARG_1);
+            }
 
-        state = erts_atomic32_read_acqb(&rp->state);
-        if (state & (ERTS_PSFLG_EXITING
-                     | ERTS_PSFLG_SIG_Q
-                     | ERTS_PSFLG_SIG_IN_Q)) {
+            result = am_true;
+        }
+
+        if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P)) {
             /*
-             * If in exiting state, trap out and send 'is alive'
-             * request and wait for it to complete termination.
-             *
-             * If process has signals enqueued, we need to
-             * send it an 'is alive' request via its signal
-             * queue in order to ensure that signal order is
-             * preserved (we may earlier have sent it an
-             * exit signal that has not been processed yet).
+             * Ensure that signal order of signals from inspected
+             * process to us is preserved...
              */
-            BIF_TRAP1(is_process_alive_trap, BIF_P, BIF_ARG_1);
+            ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, BIF_ARG_1, result);
         }
-
-        BIF_RET(am_true);
+        BIF_RET(result);
     }
 
    if (is_external_pid(BIF_ARG_1)) {
@@ -3734,6 +3820,8 @@ BIF_RETTYPE is_process_alive_1(BIF_ALIST_1)
    }
 
    BIF_ERROR(BIF_P, BADARG);
+
+   
 }
 
 static Eterm
@@ -4218,10 +4306,10 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
 			ERTS_ASSERT_IS_NOT_EXITING(BIF_P);
 			BIF_RET(am_undefined);
 		    }
-                    
                     erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
                     erts_proc_sig_fetch(p);
                     erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+                    state = erts_atomic32_read_nob(&BIF_P->state);
                     do {
                         int reds = CONTEXT_REDS;
                         sigs_done = erts_proc_sig_handle_incoming(p,
@@ -4284,10 +4372,11 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
 			ERTS_ASSERT_IS_NOT_EXITING(BIF_P);
 			BIF_RET(am_undefined);
 		    }
-                    
+
                     erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
                     erts_proc_sig_fetch(p);
                     erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+		    state = erts_atomic32_read_nob(&BIF_P->state);
                     do {
                         int reds = CONTEXT_REDS;
                         sigs_done = erts_proc_sig_handle_incoming(p,
diff --git a/erts/emulator/beam/erl_bif_port.c b/erts/emulator/beam/erl_bif_port.c
index fc415aa4e5..737a6be15f 100644
--- a/erts/emulator/beam/erl_bif_port.c
+++ b/erts/emulator/beam/erl_bif_port.c
@@ -238,8 +238,17 @@ BIF_RETTYPE erts_internal_port_command_3(BIF_ALIST_3)
     }
     else {
         /* Ensure signal order is preserved... */
-        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q))
-            ERTS_BIF_PREP_HANDLE_SIGNALS_RETURN(res, BIF_P, res);
+        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q)) {
+            Eterm from;
+            if (is_internal_port(BIF_ARG_1))
+                from = BIF_ARG_1;
+            else if (prt)
+                from = prt->common.id;
+            else
+                from = NIL;
+            ERTS_BIF_PREP_HANDLE_SIGNALS_FROM_RETURN(res, BIF_P,
+                                                     from, res);
+        }
     }
 
     return res;
@@ -287,8 +296,16 @@ BIF_RETTYPE erts_internal_port_call_3(BIF_ALIST_3)
 	ERTS_BIF_EXITED(BIF_P);
     else {
         /* Ensure signal order is preserved... */
-        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q))
-            ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q)) {
+            Eterm from;
+            if (is_internal_port(BIF_ARG_1))
+                from = BIF_ARG_1;
+            else if (prt)
+                from = prt->common.id;
+            else
+                from = NIL;
+            ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+        }
     }
 
     BIF_RET(retval);
@@ -335,8 +352,16 @@ BIF_RETTYPE erts_internal_port_control_3(BIF_ALIST_3)
 	ERTS_BIF_EXITED(BIF_P);
     else {
         /* Ensure signal order is preserved... */
-        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q))
-            ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+        if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q)) {
+            Eterm from;
+            if (is_internal_port(BIF_ARG_1))
+                from = BIF_ARG_1;
+            else if (prt)
+                from = prt->common.id;
+            else
+                from = NIL;
+            ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+        }
     }
 
     BIF_RET(retval);
@@ -382,8 +407,16 @@ BIF_RETTYPE erts_internal_port_close_1(BIF_ALIST_1)
     }
 
     /* Ensure signal order is preserved... */
-    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P))
-        ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P)) {
+        Eterm from;
+        if (is_internal_port(BIF_ARG_1))
+            from = BIF_ARG_1;
+        else if (prt)
+            from = prt->common.id;
+        else
+            from = NIL;
+        ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+    }
     
     BIF_RET(retval);
 }
@@ -426,8 +459,16 @@ BIF_RETTYPE erts_internal_port_connect_2(BIF_ALIST_2)
     }
 
     /* Ensure signal order is preserved... */
-    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P))
-        ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P)) {
+        Eterm from;
+        if (is_internal_port(BIF_ARG_1))
+            from = BIF_ARG_1;
+        else if (prt)
+            from = prt->common.id;
+        else
+            from = NIL;
+        ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+    }
     
     BIF_RET(retval);
 }
@@ -435,7 +476,7 @@ BIF_RETTYPE erts_internal_port_connect_2(BIF_ALIST_2)
 BIF_RETTYPE erts_internal_port_info_1(BIF_ALIST_1)
 {
     Eterm retval;
-    Port* prt;
+    Port* prt = NULL;
 
     if (is_internal_port(BIF_ARG_1) || is_atom(BIF_ARG_1)) {
 	prt = sig_lookup_port(BIF_P, BIF_ARG_1);
@@ -474,8 +515,16 @@ BIF_RETTYPE erts_internal_port_info_1(BIF_ALIST_1)
     }
 
     /* Ensure signal order is preserved... */
-    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P))
-        ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P)) {
+        Eterm from;
+        if (is_internal_port(BIF_ARG_1))
+            from = BIF_ARG_1;
+        else if (prt)
+            from = prt->common.id;
+        else
+            from = NIL;
+        ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+    }
     
     BIF_RET(retval);
 }
@@ -484,7 +533,7 @@ BIF_RETTYPE erts_internal_port_info_1(BIF_ALIST_1)
 BIF_RETTYPE erts_internal_port_info_2(BIF_ALIST_2)
 {
     Eterm retval;
-    Port* prt;
+    Port* prt = NULL;
 
     if (is_internal_port(BIF_ARG_1) || is_atom(BIF_ARG_1)) {
 	prt = sig_lookup_port(BIF_P, BIF_ARG_1);
@@ -523,8 +572,16 @@ BIF_RETTYPE erts_internal_port_info_2(BIF_ALIST_2)
     }
 
     /* Ensure signal order is preserved... */
-    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P))
-        ERTS_BIF_HANDLE_SIGNALS_RETURN(BIF_P, retval);
+    if (ERTS_PROC_HAS_INCOMING_SIGNALS(BIF_P)) {
+        Eterm from;
+        if (is_internal_port(BIF_ARG_1))
+            from = BIF_ARG_1;
+        else if (prt)
+            from = prt->common.id;
+        else
+            from = NIL;
+        ERTS_BIF_HANDLE_SIGNALS_FROM_RETURN(BIF_P, from, retval);
+    }
 
     BIF_RET(retval);
 }
diff --git a/erts/emulator/beam/erl_message.c b/erts/emulator/beam/erl_message.c
index 151d0b41ad..0026ecce99 100644
--- a/erts/emulator/beam/erl_message.c
+++ b/erts/emulator/beam/erl_message.c
@@ -539,6 +539,9 @@ erts_queue_proc_message(Process* sender,
                         Process* receiver, ErtsProcLocks receiver_locks,
                         ErtsMessage* mp, Eterm msg)
 {
+    if (sender == receiver)
+	(void) erts_atomic32_read_bor_nob(&sender->state,
+					  ERTS_PSFLG_MAYBE_SELF_SIGS);
     ERL_MESSAGE_TERM(mp) = msg;
     ERL_MESSAGE_FROM(mp) = sender->common.id;
     queue_messages(sender->common.id, receiver, receiver_locks,
@@ -552,6 +555,9 @@ erts_queue_proc_messages(Process* sender,
                          Process* receiver, ErtsProcLocks receiver_locks,
                          ErtsMessage* first, ErtsMessage** last, Uint len)
 {
+    if (sender == receiver)
+	(void) erts_atomic32_read_bor_nob(&sender->state,
+					  ERTS_PSFLG_MAYBE_SELF_SIGS);
     queue_messages(sender->common.id, receiver, receiver_locks,
                    prepend_pending_sig_maybe(sender, receiver, first),
                    last, len);
diff --git a/erts/emulator/beam/erl_proc_sig_queue.c b/erts/emulator/beam/erl_proc_sig_queue.c
index 7cb5f9e491..bfddf9e48f 100644
--- a/erts/emulator/beam/erl_proc_sig_queue.c
+++ b/erts/emulator/beam/erl_proc_sig_queue.c
@@ -729,7 +729,7 @@ proc_queue_signal(ErtsPTabElementCommon *sender, Eterm from, Eterm pid,
     /* Tracing requires sender for local procs and ports. The assertions below
      * will not catch errors after time-of-death, but ought to find most
      * problems. */
-    ASSERT(sender != NULL ||
+    ASSERT(sender != NULL || op == ERTS_SIG_Q_OP_FLUSH ||
            (is_normal_sched && esdp->pending_signal.sig == sig) ||
            (!(is_internal_pid(from) &&
               erts_proc_lookup(from) != NULL) &&
@@ -824,6 +824,11 @@ proc_queue_signal(ErtsPTabElementCommon *sender, Eterm from, Eterm pid,
     sigp = &first;
 
 first_last_done:
+
+    if ((void *) sender == (void *) rp)
+	(void) erts_atomic32_read_bor_nob(&((Process *) sender)->state,
+					  ERTS_PSFLG_MAYBE_SELF_SIGS);
+
     sig->common.specific.next = NULL;
 
     /* may add signals before sig */
@@ -2751,6 +2756,83 @@ erts_proc_sig_send_move_msgq_off_heap(Eterm to)
     }
 }
 
+void
+erts_proc_sig_init_flush_signals(Process *c_p, int flags, Eterm id)
+{
+    int force_flush_buffers = 0, enqueue_mq, fetch_sigs;
+    ErtsSignal *sig;
+
+    ERTS_LC_ASSERT(ERTS_PROC_LOCK_MAIN == erts_proc_lc_my_proc_locks(c_p));
+
+    ASSERT(!(c_p->sig_qs.flags & (FS_FLUSHING_SIGS|FS_FLUSHED_SIGS)));
+    ASSERT(flags);
+    ASSERT((flags & ~ERTS_PROC_SIG_FLUSH_FLGS) == 0);
+    ASSERT(!(flags & ERTS_PROC_SIG_FLUSH_FLG_FROM_ID)
+           || is_internal_pid(id) || is_internal_port(id));
+    
+    sig = erts_alloc(ERTS_ALC_T_SIG_DATA, sizeof(ErtsSignalCommon));
+    sig->common.next = NULL;
+    sig->common.specific.attachment = NULL;
+    sig->common.tag = ERTS_PROC_SIG_MAKE_TAG(ERTS_SIG_Q_OP_FLUSH,
+					     ERTS_SIG_Q_TYPE_UNDEFINED,
+					     0);
+    switch (flags) {
+    case ERTS_PROC_SIG_FLUSH_FLG_FROM_ALL:
+        id = c_p->common.id;
+        force_flush_buffers = !0;
+        /* Fall through... */
+    case ERTS_PROC_SIG_FLUSH_FLG_FROM_ID:
+        if (!proc_queue_signal(NULL, id, c_p->common.id, sig,
+                               force_flush_buffers, ERTS_SIG_Q_OP_FLUSH))
+            ERTS_INTERNAL_ERROR("Failed to send flush signal to ourselves");
+        enqueue_mq = 0;
+        fetch_sigs = !0;
+        break;
+    case ERTS_PROC_SIG_FLUSH_FLG_CLEAN_SIGQ:
+        enqueue_mq = !0;
+        fetch_sigs = 0;
+        break;
+    default:
+        enqueue_mq = !!(flags & ERTS_PROC_SIG_FLUSH_FLG_CLEAN_SIGQ);
+        fetch_sigs = !0;
+        break;
+    }
+
+    erts_set_gc_state(c_p, 0);
+
+    if (fetch_sigs) {
+        erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
+        erts_proc_sig_fetch(c_p);
+        erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+    }
+    
+    c_p->sig_qs.flags |= FS_FLUSHING_SIGS;
+
+    if (enqueue_mq) {
+        if (!c_p->sig_qs.cont) {
+            c_p->sig_qs.flags |= FS_FLUSHED_SIGS;
+            erts_free(ERTS_ALC_T_SIG_DATA, sig);
+        }
+        else {
+            if (!c_p->sig_qs.nmsigs.last) {
+                ASSERT(!c_p->sig_qs.nmsigs.next);
+                c_p->sig_qs.nmsigs.next = c_p->sig_qs.cont_last;
+            }
+            else {
+                ErtsSignal *lsig = (ErtsSignal *) *c_p->sig_qs.nmsigs.last;
+                ASSERT(c_p->sig_qs.nmsigs.next);
+                ASSERT(lsig && !lsig->common.specific.next);
+                lsig->common.specific.next = c_p->sig_qs.cont_last;
+            }
+
+            c_p->sig_qs.nmsigs.last = c_p->sig_qs.cont_last;
+            *c_p->sig_qs.cont_last = (ErtsMessage *) sig;
+            c_p->sig_qs.cont_last = &sig->common.next;
+        }
+    }
+
+}
+
 static int
 handle_rpc(Process *c_p, ErtsProcSigRPC *rpc, int cnt, int limit, int *yieldp)
 {
@@ -5172,7 +5172,7 @@ erts_proc_sig_handle_incoming(Process *c
                               int *redsp, int max_reds, int local_only)
 {
     Eterm tag;
-    erts_aint32_t state;
+    erts_aint32_t state = *statep;
     int yield, cnt, limit, abs_lim, msg_tracing, save_in_msgq;
     ErtsMessage *sig, ***next_nm_sig;
     ErtsSigRecvTracing tracing;
@@ -5182,8 +5182,7 @@ erts_proc_sig_handle_incoming(Process *c
     ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
     ERTS_LC_ASSERT(ERTS_PROC_LOCK_MAIN == erts_proc_lc_my_proc_locks(c_p));
 
-    state = erts_atomic32_read_nob(&c_p->state);
-    if (!local_only) {
+    if (!local_only && !(c_p->sig_qs.flags & FS_FLUSHING_SIGS)) {
         if (ERTS_PSFLG_SIG_IN_Q & state) {
             erts_proc_sig_queue_lock(c_p);
             erts_proc_sig_fetch(c_p);
@@ -5694,6 +5775,20 @@ erts_proc_sig_handle_incoming(Process *c_p, erts_aint32_t *statep,
             ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
             break;
 
+	case ERTS_SIG_Q_OP_FLUSH:
+            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
+	    ASSERT(c_p->sig_qs.flags & FS_FLUSHING_SIGS);
+	    c_p->sig_qs.flags |= FS_FLUSHED_SIGS;
+            remove_nm_sig(c_p, sig, next_nm_sig);
+	    erts_free(ERTS_ALC_T_SIG_DATA, sig);
+            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
+	    /*
+	     * The caller has been exclusively handling signals until this
+	     * point. Break out and let the process continue with other
+	     * things as well...
+	     */
+	    goto stop;
+
         case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE: {
             Uint16 type = ERTS_PROC_SIG_TYPE(tag);
 
@@ -5810,7 +5905,7 @@ stop: {
                     *next_nm_sig = &c_p->sig_qs.cont;
                 if (c_p->sig_qs.nmsigs.last == tracing.messages.next)
                     c_p->sig_qs.nmsigs.last = &c_p->sig_qs.cont;
-                *statep = erts_atomic32_read_nob(&c_p->state);
+		state = erts_atomic32_read_nob(&c_p->state);
             }
             else {
                 ASSERT(!c_p->sig_qs.nmsigs.next);
@@ -5818,7 +5913,6 @@ stop: {
                 state = erts_atomic32_read_band_nob(&c_p->state,
                                                     ~ERTS_PSFLG_SIG_Q);
                 state &= ~ERTS_PSFLG_SIG_Q;
-                *statep = state;
             }
 
             if (tracing.messages.next != &c_p->sig_qs.cont) {
@@ -5864,7 +5958,7 @@ stop: {
 
             ASSERT(c_p->sig_qs.cont);
 
-            *statep = erts_atomic32_read_nob(&c_p->state);
+            state = erts_atomic32_read_nob(&c_p->state);
 
             res = 0;
         }
@@ -5897,10 +5991,21 @@ stop: {
             state = erts_atomic32_read_band_nob(&c_p->state,
                                                 ~ERTS_PSFLG_SIG_Q);
             state &= ~ERTS_PSFLG_SIG_Q;
-            *statep = state;
             res = !0;
         }
 
+	if (!!(state & ERTS_PSFLG_MAYBE_SELF_SIGS)
+	    & !(state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q))) {
+	    /*
+	     * We know we do not have any outstanding signals
+	     * from ourselves...
+	     */
+	    (void) erts_atomic32_read_band_nob(&c_p->state,
+					       ~ERTS_PSFLG_MAYBE_SELF_SIGS);
+	    state &= ~ERTS_PSFLG_MAYBE_SELF_SIGS;
+	}
+	*statep = state;
+
         /* Ensure that 'save' doesn't point to a receive marker... */
         if (*c_p->sig_qs.save
             && ERTS_SIG_IS_RECV_MARKER(*c_p->sig_qs.save)) {
@@ -6183,6 +6288,12 @@ erts_proc_sig_handle_exit(Process *c_p, Sint *redsp,
 	    }
             break;
 
+	case ERTS_SIG_Q_OP_FLUSH:
+	    ASSERT(c_p->sig_qs.flags & FS_FLUSHING_SIGS);
+	    c_p->sig_qs.flags |= FS_FLUSHED_SIGS;
+	    erts_free(ERTS_ALC_T_SIG_DATA, sig); 
+	    break;
+
         case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE:
             destroy_trace_info((ErtsSigTraceInfo *) sig);
             break;
@@ -6280,6 +6391,7 @@ clear_seq_trace_token(ErtsMessage *sig)
         case ERTS_SIG_Q_OP_RPC:
         case ERTS_SIG_Q_OP_RECV_MARK:
         case ERTS_SIG_Q_OP_ADJ_MSGQ:
+	case ERTS_SIG_Q_OP_FLUSH:
             break;
 
         default:
@@ -6292,8 +6404,33 @@ clear_seq_trace_token(ErtsMessage *sig)
 void
 erts_proc_sig_clear_seq_trace_tokens(Process *c_p)
 {
-    erts_proc_sig_fetch(c_p);
-    ERTS_FOREACH_SIG_PRIVQS(c_p, sig, clear_seq_trace_token(sig));
+    int ix;
+    ErtsSignalInQueueBufferArray *bap;
+    int unget_info;
+    ErtsMessage *qs[] = {c_p->sig_qs.first,
+                         c_p->sig_qs.cont,
+                         c_p->sig_inq.first};
+
+    ERTS_LC_ASSERT(erts_thr_progress_is_blocking());
+
+    for (ix = 0; ix < sizeof(qs)/sizeof(qs[0]); ix++) {
+        ErtsMessage *sigp;
+        for (sigp = qs[ix]; sigp; sigp = sigp->next)
+            clear_seq_trace_token(sigp);
+    }
+
+    bap = erts_proc_sig_queue_get_buffers(c_p, &unget_info);
+    if (bap) {
+        for (ix = 0; ix < ERTS_PROC_SIG_INQ_BUFFERED_NR_OF_BUFFERS; ix++) {
+            ErtsSignalInQueueBuffer* bp = &bap->slots[ix];
+            if (bp->b.alive) {
+                ErtsMessage *sigp;
+                for (sigp = bp->b.queue.first; sigp; sigp = sigp->next)
+                    clear_seq_trace_token(sigp);
+            }
+        }
+        erts_proc_sig_queue_unget_buffers(bap, unget_info);
+    }
 }
 
 Uint
@@ -6419,6 +6556,10 @@ erts_proc_sig_signal_size(ErtsSignal *sig)
         break;
     }
 
+    case ERTS_SIG_Q_OP_FLUSH:
+	size = sizeof(ErtsSignalCommon);
+	break;
+
     case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE:
         size = sizeof(ErtsSigTraceInfo);
         break;
@@ -6537,6 +6678,7 @@ erts_proc_sig_receive_helper(Process *c_p,
         if (max_reds < reds)
             max_reds = reds;
 #endif
+	state = erts_atomic32_read_nob(&c_p->state);
         (void) erts_proc_sig_handle_incoming(c_p, &state, &reds,
                                              max_reds, !0);
         consumed_reds += reds;
@@ -7246,7 +7388,8 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
                                        Process *rp,
                                        ErtsProcLocks rp_locks,
                                        int info_on_self,
-                                       ErtsMessageInfo *mip)
+                                       ErtsMessageInfo *mip,
+                                       Sint *msgq_len_p)
 {
     Uint tot_heap_size;
     ErtsMessage *mp, **mpp;
@@ -7320,7 +7463,11 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
 	mp = mp->next;
     }
 
-    ASSERT(c_p->sig_qs.len == i);
+    
+    ASSERT(info_on_self || c_p->sig_qs.len == i);
+    ASSERT(!info_on_self || c_p->sig_qs.len >= i);
+
+    *msgq_len_p = i;
 
     return tot_heap_size;
 }
@@ -7409,7 +7556,6 @@ erts_internal_dirty_process_handle_signals_1(BIF_ALIST_1)
         BIF_RET(am_normal); /* will handle signals itself... */
     }
     else {
-        erts_aint32_t state;
         int done;
         Eterm res = am_false;
         int reds = 0;
@@ -7708,6 +7856,7 @@ erts_proc_sig_debug_foreach_sig(Process *c_p,
                 case ERTS_SIG_Q_OP_PROCESS_INFO:
                 case ERTS_SIG_Q_OP_RECV_MARK:
                 case ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK:
+		case ERTS_SIG_Q_OP_FLUSH:
                     break;
 
                 default:
diff --git a/erts/emulator/beam/erl_proc_sig_queue.h b/erts/emulator/beam/erl_proc_sig_queue.h
index b3aefff0b0..deb1b802e1 100644
--- a/erts/emulator/beam/erl_proc_sig_queue.h
+++ b/erts/emulator/beam/erl_proc_sig_queue.h
@@ -110,7 +110,7 @@ typedef struct {
  * Note that not all signal are handled using this functionality!
  */
 
-#define ERTS_SIG_Q_OP_MAX 18
+#define ERTS_SIG_Q_OP_MAX 19
 
 #define ERTS_SIG_Q_OP_EXIT                      0  /* Exit signal due to bif call */
 #define ERTS_SIG_Q_OP_EXIT_LINKED               1  /* Exit signal due to link break*/
@@ -130,7 +130,8 @@ typedef struct {
 #define ERTS_SIG_Q_OP_ALIAS_MSG                 15
 #define ERTS_SIG_Q_OP_RECV_MARK                 16
 #define ERTS_SIG_Q_OP_UNLINK_ACK                17
-#define ERTS_SIG_Q_OP_ADJ_MSGQ                  ERTS_SIG_Q_OP_MAX
+#define ERTS_SIG_Q_OP_ADJ_MSGQ                  18
+#define ERTS_SIG_Q_OP_FLUSH			ERTS_SIG_Q_OP_MAX
 
 #define ERTS_SIG_Q_TYPE_MAX (ERTS_MON_LNK_TYPE_MAX + 10)
 
@@ -1133,6 +1134,9 @@ erts_proc_sig_send_move_msgq_off_heap(Eterm to);
  *
  * @param[out]    statep        Pointer to process state after
  *                              signal handling. May not be NULL.
+ *                              The state should recently have
+ *                              been updated before calling
+ *                              this function.
  *
  * @param[in,out] redsp         Pointer to an integer containing
  *                              reductions. On input, the amount
@@ -1253,6 +1257,58 @@ erts_proc_sig_receive_helper(Process *c_p, int fcalls,
                              int neg_o_reds, ErtsMessage **msgpp,
                              int *get_outp);
 
+/*
+ * CLEAN_SIGQ - Flush until middle queue is empty, i.e.
+ *              the content of inner+middle queue equals
+ *              the message queue.
+ */
+#define ERTS_PROC_SIG_FLUSH_FLG_CLEAN_SIGQ          (1 << 0)
+/*
+ * FROM_ALL   - Flush signals from all local senders (processes
+ *              and ports).
+ */
+#define ERTS_PROC_SIG_FLUSH_FLG_FROM_ALL            (1 << 1)
+/*
+ * FROM_ID    - Flush signals from process or port identified
+ *              by 'id'.
+ */
+#define ERTS_PROC_SIG_FLUSH_FLG_FROM_ID             (1 << 2)
+
+/*
+ * All erts_proc_sig_init_flush_signals() flags.
+ */
+#define ERTS_PROC_SIG_FLUSH_FLGS                                \
+    (ERTS_PROC_SIG_FLUSH_FLG_CLEAN_SIGQ                         \
+     | ERTS_PROC_SIG_FLUSH_FLG_FROM_ALL                         \
+     | ERTS_PROC_SIG_FLUSH_FLG_FROM_ID)
+
+/**
+ *
+ * @brief Initialize flush of signals from another process or port
+ *
+ * Inserts a flush signal in the outer signal queue of
+ * current process and sets the FS_FLUSHING_SIGS flag in
+ * 'c_p->sig_qs.flags'. When the flush signal has been
+ * handled the FS_FLUSHED_SIGS flag is set as well.
+ *
+ * While the flushing is ongoing the process *should* only
+ * handle incoming signals and not execute Erlang code. When
+ * the functionality that initiated the flush detects that
+ * the flush is done by the FS_FLUSHED_SIGS flag being set,
+ * it should clear both the FS_FLUSHED_SIGS flag and the
+ * FS_FLUSHING_SIGS flag.
+ *
+ * @param[in]   c_p             Pointer to process struct of
+ *                              currently executing process.
+ *              flags           Flags indicating how to flush.
+ *                              (see above).
+ *              from            Identifier of sender to flush
+ *                              signals from in case the
+ *                              FROM_ID flag is set.
+ */
+void
+erts_proc_sig_init_flush_signals(Process *c_p, int flags, Eterm from);
+
 /**
  *
  * @brief Fetch signals from the outer queue
@@ -1370,12 +1426,16 @@ typedef struct {
  *
  * @param[in]   mip             Pointer to array of
  *                              ErtsMessageInfo structures.
+ *
+ * @param[out]  msgq_lenp       Pointer to integer containing
+ *                              amount of messages.
  */
 Uint erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
                                             Process *rp,
                                             ErtsProcLocks rp_locks,
                                             int info_on_self,
-                                            ErtsMessageInfo *mip);
+                                            ErtsMessageInfo *mip,
+                                            Sint *msgq_lenp);
 
 /**
  *
@@ -1744,7 +1744,9 @@ erts_proc_sig_fetch(Process *proc)
                        == (ERTS_PROC_LOCK_MAIN
                            | ERTS_PROC_LOCK_MSGQ)));
 
-    ASSERT(!(proc->sig_qs.flags & FS_HANDLING_SIGS));
+    ASSERT(!(proc->sig_qs.flags & FS_FLUSHING_SIGS)
+           || ERTS_PROC_IS_EXITING(proc)
+           || ERTS_IS_CRASH_DUMPING);
 
     ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(proc);
     ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc, !0);
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index ff81b453a7..393de2b7b1 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -10063,27 +10063,30 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
 
             if (state & ERTS_PSFLG_RUNNING_SYS) {
                 if (state & (ERTS_PSFLG_SIG_Q|ERTS_PSFLG_SIG_IN_Q)) {
-                    int local_only = (!!(p->sig_qs.flags & FS_LOCAL_SIGS_ONLY)
-                                      & !(state & (ERTS_PSFLG_SUSPENDED|ERTS_PSFLGS_DIRTY_WORK)));
-                    if (!local_only | !!(state & ERTS_PSFLG_SIG_Q)) {
-                        int sig_reds;
-                        /*
-                         * If we have dirty work scheduled we allow
-                         * usage of all reductions since we need to
-                         * handle all signals before doing dirty
-                         * work...
-                         */
-                        if (state & ERTS_PSFLGS_DIRTY_WORK)
-                            sig_reds = reds;
-                        else
-                            sig_reds = ERTS_SIG_HANDLE_REDS_MAX_PREFERED;
-                        (void) erts_proc_sig_handle_incoming(p,
-                                                             &state,
-                                                             &sig_reds,
-                                                             sig_reds,
-                                                             local_only);
-                        reds -= sig_reds;
-                    }
+		    int sig_reds;
+		    /*
+		     * If we have dirty work scheduled we allow
+		     * usage of all reductions since we need to
+		     * handle all signals before doing dirty
+		     * work...
+                     *
+                     * If a BIF is flushing signals, we also allow
+                     * usage of all reductions since the BIF cannot
+                     * continue exectution until the flush
+                     * completes...
+		     */
+		    if (state & ERTS_PSFLGS_DIRTY_WORK)
+			sig_reds = reds;
+		    else if (p->sig_qs.flags & FS_FLUSHING_SIGS)
+                        sig_reds = reds;
+                    else
+			sig_reds = ERTS_SIG_HANDLE_REDS_MAX_PREFERED;
+		    (void) erts_proc_sig_handle_incoming(p,
+							 &state,
+							 &sig_reds,
+							 sig_reds,
+							 0);
+		    reds -= sig_reds;
                 }
                 if ((state & (ERTS_PSFLG_SYS_TASKS
                               | ERTS_PSFLG_EXITING)) == ERTS_PSFLG_SYS_TASKS) {
@@ -10093,8 +10096,14 @@ Process *erts_schedule(ErtsSchedulerData *esdp, Process *p, int calls)
                      * hand written beam assembly in
                      * prim_eval:'receive'. If GC is delayed we are
                      * not allowed to execute system tasks.
+                     *
+                     * We also don't allow execution of system tasks
+                     * if a BIF is flushing signals, since there are
+                     * system tasks that might need to fetch from the
+                     * outer signal queue...
                      */
-                    if (!(p->flags & F_DELAY_GC)) {
+                    if (!(p->flags & F_DELAY_GC)
+                        && !(p->sig_qs.flags & FS_FLUSHING_SIGS)) {
                         int cost = execute_sys_tasks(p, &state, reds);
                         calls += cost;
                         reds -= cost;
@@ -10622,15 +10631,19 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
 	    break;
         case ERTS_PSTT_PRIO_SIG: {
             erts_aint32_t fail_state, state;
-            int sig_res, sig_reds = reds;
+            int sig_res, sig_reds;
 	    st_res = am_false;
 
+            ASSERT(!(c_p->sig_qs.flags & FS_FLUSHING_SIGS));
+
             if (st->arg[0] == am_false) {
                 erts_proc_sig_queue_lock(c_p);
                 erts_proc_sig_fetch(c_p);
                 erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+                st->arg[0] = am_true;
             }
 
+	    state = erts_atomic32_read_nob(&c_p->state);
             sig_reds = reds;
             sig_res = erts_proc_sig_handle_incoming(c_p, &state, &sig_reds,
                                                     reds, !0);
@@ -10644,8 +10657,6 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
             if (sig_res)
                 break;
 
-            st->arg[0] = am_true;
-
             fail_state = ERTS_PSFLG_EXITING;
 
             if (schedule_process_sys_task(c_p, st_prio, st, &fail_state)) {
@@ -10656,6 +10667,7 @@ execute_sys_tasks(Process *c_p, erts_aint32_t *statep, int in_reds)
                 state = erts_atomic32_read_nob(&c_p->state);
                 exit_permanent_prio_elevation(c_p, state, st_prio);
             }
+
             break;
         }
         case ERTS_PSTT_TEST:
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index 81958e373a..0459aeaba5 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1246,8 +1246,9 @@ void erts_check_for_holes(Process* p);
    process table. Always ACTIVE while EXITING. Never
    SUSPENDED unless also FREE. */
 #define ERTS_PSFLG_EXITING		ERTS_PSFLG_BIT(5)
-/* UNUSED */
-#define ERTS_PSFLG_UNUSED		ERTS_PSFLG_BIT(6)
+/* MAYBE_SELF_SIGS - We might have outstanding signals
+   from ourselves to ourselvs. */
+#define ERTS_PSFLG_MAYBE_SELF_SIGS	ERTS_PSFLG_BIT(6)
 /* ACTIVE - Process "wants" to execute */
 #define ERTS_PSFLG_ACTIVE		ERTS_PSFLG_BIT(7)
 /* IN_RUNQ - Real process (not proxy) struct used in a
@@ -1572,10 +1573,12 @@ extern int erts_system_profile_ts_type;
 #define FS_OFF_HEAP_MSGQ       (1 << 0) /* Off heap msg queue */
 #define FS_ON_HEAP_MSGQ        (1 << 1) /* On heap msg queue */
 #define FS_OFF_HEAP_MSGQ_CHNG  (1 << 2) /* Off heap msg queue changing */
-#define FS_LOCAL_SIGS_ONLY     (1 << 3) /* Handle privq sigs only */
+#define FS_UNUSED              (1 << 3) /* Unused */
 #define FS_HANDLING_SIGS       (1 << 4) /* Process is handling signals */
 #define FS_WAIT_HANDLE_SIGS    (1 << 5) /* Process is waiting to handle signals */
 #define FS_DELAYED_PSIGQS_LEN  (1 << 6) /* Delayed update of sig_qs.len */
+#define FS_FLUSHING_SIGS       (1 << 7) /* Currently flushing signals */
+#define FS_FLUSHED_SIGS        (1 << 8) /* Flushing of signals completed */
 
 /*
  * F_DISABLE_GC and F_DELAY_GC are similar. Both will prevent
diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index f95c7ad1d7..9fa5969b5e 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -159,9 +159,12 @@ Uint erts_process_memory(Process *p, int include_sigs_in_transit)
          * Size of message queue plus size of all signals
          * in transit to the process!
          */
-        erts_proc_sig_queue_lock(p);
-        erts_proc_sig_fetch(p);
-        erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+        if (!(p->sig_qs.flags & FS_FLUSHING_SIGS)
+            || ERTS_IS_CRASH_DUMPING) {
+            erts_proc_sig_queue_lock(p);
+            erts_proc_sig_fetch(p);
+            erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+        }
 
         ERTS_FOREACH_SIG_PRIVQS(
             p, mp,
@@ -228,7 +231,9 @@ dump_process_info(fmtfn_t to, void *to_arg, Process *p)
     if (ERTS_TRACE_FLAGS(p) & F_SENSITIVE)
         return;
 
-    erts_proc_sig_fetch(p);
+    if (!(p->sig_qs.flags & FS_FLUSHING_SIGS) || ERTS_IS_CRASH_DUMPING) {
+        erts_proc_sig_fetch(p);
+    }
 
     if (p->sig_qs.first || p->sig_qs.cont) {
 	erts_print(to, to_arg, "=proc_messages:%T\n", p->common.id);
@@ -1123,8 +1128,8 @@ erts_dump_extended_process_state(fmtfn_t to, void *to_arg, erts_aint32_t psflg)
                 erts_print(to, to_arg, "FREE"); break;
             case ERTS_PSFLG_EXITING:
                 erts_print(to, to_arg, "EXITING"); break;
-            case ERTS_PSFLG_UNUSED:
-                erts_print(to, to_arg, "UNUSED"); break;
+            case ERTS_PSFLG_MAYBE_SELF_SIGS:
+                erts_print(to, to_arg, "MAYBE_SELF_SIGS"); break;
             case ERTS_PSFLG_ACTIVE:
                 erts_print(to, to_arg, "ACTIVE"); break;
             case ERTS_PSFLG_IN_RUNQ:
diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl
index c5be79528b..ee6c494145 100644
--- a/erts/emulator/test/bif_SUITE.erl
+++ b/erts/emulator/test/bif_SUITE.erl
@@ -37,6 +37,7 @@
 	 error_stacktrace_during_call_trace/1,
          group_leader_prio/1, group_leader_prio_dirty/1,
          is_process_alive/1,
+         is_process_alive_signal_from/1,
          process_info_blast/1,
          os_env_case_sensitivity/1,
          verify_middle_queue_save/1,
@@ -57,7 +58,8 @@ all() ->
      erl_crash_dump_bytes, min_max, erlang_halt, is_builtin,
      error_stacktrace, error_stacktrace_during_call_trace,
      group_leader_prio, group_leader_prio_dirty,
-     is_process_alive, process_info_blast, os_env_case_sensitivity,
+     is_process_alive, is_process_alive_signal_from,
+     process_info_blast, os_env_case_sensitivity,
      verify_middle_queue_save, test_length,fixed_apply_badarg,
      external_fun_apply3].
 
@@ -1205,6 +1207,51 @@ is_process_alive(Config) when is_list(Config) ->
                   Ps),
     ok.
 
+is_process_alive_signal_from(Config) when is_list(Config) ->
+    process_flag(priority, high),
+    process_flag(scheduler, 1),
+    Schdlr = case erlang:system_info(schedulers_online) of
+                 1 -> 1;
+                 _ -> 2
+             end,
+    X = is_process_alive_signal_from_test(100000, 0, Schdlr),
+    erlang:display({exits_detected, X}),
+    {comment, integer_to_list(X) ++ " exited processes detected"}.
+
+is_process_alive_signal_from_test(0, X, _Schdlr) ->
+    X;
+is_process_alive_signal_from_test(N, X, Schdlr) ->
+    Tester = self(),
+    {Testee, TMon} = spawn_opt(fun () ->
+                                       Mon = erlang:monitor(process, Tester),
+                                       Tester ! {self(), ready},
+                                       busy_wait_go(),
+                                       _ = erlang:demonitor(Mon),
+                                       exit(normal)
+                               end,
+                               [link,
+                                monitor,
+                                {priority, high},
+                                {scheduler, Schdlr}]),
+    receive {Testee, ready} -> ok end,
+    {monitored_by, MBList1} = process_info(self(), monitored_by),
+    true = lists:member(Testee, MBList1),
+    erlang:yield(),
+    Testee ! {go, ok},
+    erlang:yield(),
+    NewX = case erlang:is_process_alive(Testee) of
+               true ->
+                   X;
+               false ->
+                   %% Demonitor signal should have reached us before the
+                   %% is-process-alive reply...
+                   {monitored_by, MBList2} = process_info(self(), monitored_by),
+                   false = lists:member(Testee, MBList2),
+                   X+1
+           end,
+    receive {'DOWN', TMon, process, Testee, normal} -> ok end,
+    is_process_alive_signal_from_test(N-1, NewX, Schdlr).
+
 process_info_blast(Config) when is_list(Config) ->
     Tester = self(),
     NoAttackers = 1000,
@@ -1396,7 +1443,16 @@ external_fun_apply3(_Config) ->
     ok.
 
 %% helpers
-    
+
+busy_wait_go() ->
+    receive
+        {go, Info} ->
+            Info
+    after
+        0 ->
+            busy_wait_go()
+    end.
+
 id(I) -> I.
 
 %% Get code path, including the path for the erts application.
diff --git a/erts/emulator/test/nif_SUITE.erl b/erts/emulator/test/nif_SUITE.erl
index 4aa9cf6b9f..2f28b4a0e9 100644
--- a/erts/emulator/test/nif_SUITE.erl
+++ b/erts/emulator/test/nif_SUITE.erl
@@ -1152,6 +1152,7 @@ monitor_process_c(Config) ->
     Pid = spawn_link(fun() ->
                              R_ptr = alloc_monitor_resource_nif(),
                              {0,Mon} = monitor_process_nif(R_ptr, self(), true, Papa),
+                             receive after 1000 -> ok end,
                              [R_ptr] = monitored_by(self()),
                              put(store, make_resource(R_ptr)),
                              ok = release_resource(R_ptr),
@@ -1159,8 +1160,8 @@ monitor_process_c(Config) ->
                              Papa ! {self(), done, R_ptr, Mon},
                              exit
                      end),
-    [{Pid, done, R_ptr, Mon1},
-     {monitor_resource_down, R_ptr, Pid, Mon2}] = flush(2),
+    receive {Pid, done, R_ptr, Mon1} -> ok end,
+    [{monitor_resource_down, R_ptr, Pid, Mon2}] = flush(1),
     compare_monitors_nif(Mon1, Mon2),
     {R_ptr, _, 1} = last_resource_dtor_call(),
     ok.
diff --git a/erts/emulator/test/port_SUITE.erl b/erts/emulator/test/port_SUITE.erl
index 4a3ecef397..1fa6922648 100644
--- a/erts/emulator/test/port_SUITE.erl
+++ b/erts/emulator/test/port_SUITE.erl
@@ -1915,6 +1915,7 @@ otp_5112(Config) when is_list(Config) ->
     true = lists:member(Port, Links1),
     Port ! {self(), {command, ""}},
     wait_until(fun () -> lists:member(Port, erlang:ports()) == false end),
+    receive after 1000 -> ok end, %% Give signal some time to propagate...
     {links, Links2} = process_info(self(),links),
     io:format("Links2: ~p~n",[Links2]),
     false = lists:member(Port, Links2), %% This used to fail
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 0e549d424c..23a208adb2 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -49,6 +49,10 @@
          process_info_smoke_all/1,
          process_info_status_handled_signal/1,
          process_info_reductions/1,
+         process_info_self_signal/1,
+         process_info_self_msgq_len/1,
+         process_info_self_msgq_len_messages/1,
+         process_info_self_msgq_len_more/1,
 	 bump_reductions/1, low_prio/1, binary_owner/1, yield/1, yield2/1,
 	 otp_4725/1, dist_unlink_ack_exit_leak/1, bad_register/1,
          garbage_collect/1, otp_6237/1, process_info_messages/1,
@@ -107,21 +111,8 @@ suite() ->
 all() ->
     [spawn_with_binaries, t_exit_1, {group, t_exit_2},
      trap_exit_badarg, trap_exit_badarg_in_bif,
-     t_process_info, process_info_other, process_info_other_msg,
-     process_info_other_dist_msg, process_info_other_status,
-     process_info_2_list,
-     process_info_lock_reschedule,
-     process_info_lock_reschedule2,
-     process_info_lock_reschedule3,
-     process_info_other_message_queue_len_signal_race,
-     process_info_garbage_collection,
-     process_info_parent,
-     process_info_smoke_all,
-     process_info_status_handled_signal,
-     process_info_reductions,
      bump_reductions, low_prio, yield, yield2, otp_4725,
-     dist_unlink_ack_exit_leak,
-     bad_register, garbage_collect, process_info_messages,
+     dist_unlink_ack_exit_leak, bad_register, garbage_collect,
      process_flag_badarg,
      process_flag_fullsweep_after, process_flag_heap_size,
      spawn_opt_heap_size, spawn_opt_max_heap_size,
@@ -129,6 +120,7 @@ all() ->
      spawn_request_reply_option,
      dist_spawn_arg_list_mixup,
      otp_6237,
+     {group, process_info_bif},
      {group, processes_bif},
      {group, otp_7738}, garb_other_running,
      {group, system_task},
@@ -159,6 +151,24 @@ groups() ->
        processes_small_tab, processes_this_tab,
        processes_last_call_trap, processes_apply_trap,
        processes_gc_trap, processes_term_proc_list]},
+     {process_info_bif, [],
+      [t_process_info, process_info_messages,
+       process_info_other, process_info_other_msg,
+       process_info_other_message_queue_len_signal_race,
+       process_info_other_dist_msg, process_info_other_status,
+       process_info_2_list,
+       process_info_lock_reschedule,
+       process_info_lock_reschedule2,
+       process_info_lock_reschedule3,
+       process_info_garbage_collection,
+       process_info_parent,
+       process_info_smoke_all,
+       process_info_status_handled_signal,
+       process_info_reductions,
+       process_info_self_signal,
+       process_info_self_msgq_len,
+       process_info_self_msgq_len_messages,
+       process_info_self_msgq_len_more]},
      {otp_7738, [],
       [otp_7738_waiting, otp_7738_suspended,
        otp_7738_resume]},
@@ -1351,6 +1361,146 @@ pi_reductions_main_unlocker_loop(Other) ->
     erlang:yield(),
     pi_reductions_main_unlocker_loop(Other).
 
+process_info_self_signal(Config) when is_list(Config) ->
+    %% Test that signals that we have sent to ourselves are
+    %% visible in process_info() result. This is not strictly
+    %% a necessary property, but implemented so now. See
+    %% process_info.c:process_info_bif() for more info.
+    Self = self(),
+    Ref = make_ref(),
+    pi_sig_spam_test(fun () ->
+                             process_info_self_signal_spammer(Self)
+                     end,
+                     fun () ->
+                             self() ! Ref,
+                             process_info(self(), messages)
+                     end,
+                     fun (Res) ->
+                             {messages, [Ref]} = Res
+                     end).
+
+process_info_self_signal_spammer(To) ->
+    erlang:demonitor(erlang:monitor(process, To)),
+    process_info_self_signal_spammer(To).
+
+process_info_self_msgq_len(Config) when is_list(Config) ->
+    %% Spam ourselves with signals forcing us to flush own
+    %% signal queue..
+    Self = self(),
+    pi_sig_spam_test(fun () ->
+                             process_info_self_msgq_len_spammer(Self)
+                     end,
+                     fun () ->
+                             process_info(self(), message_queue_len)
+                     end,
+                     fun (Res) ->
+                             {message_queue_len, Len} = Res,
+                             true = Len > 0,
+                             ok
+                     end).
+
+
+process_info_self_msgq_len_messages(Config) when is_list(Config) ->
+    %% Spam ourselves with signals normally forcing us to flush own
+    %% signal queue, but since we also want messages wont be flushed...
+    Self = self(),
+    pi_sig_spam_test(fun () ->
+                             process_info_self_msgq_len_spammer(Self, 100000)
+                     end,
+                     fun () ->
+                             process_info(self(),
+                                          [message_queue_len,
+                                           messages])
+                     end,
+                     fun (Res) ->
+                             [{message_queue_len, Len},
+                              {messages, Msgs}] = Res,
+                             Len = length(Msgs),
+                             ok
+                     end).
+
+process_info_self_msgq_len_more(Config) when is_list(Config) ->
+    self() ! hej,
+    BodyRes = process_info_self_msgq_len_more_caller_body(),
+    ok = process_info_self_msgq_len_more_caller_body_result(BodyRes),
+    TailRes = process_info_self_msgq_len_more_caller_tail(),
+    ok = process_info_self_msgq_len_more_caller_tail_result(TailRes),
+    receive hej -> ok end,
+    %% Check that current_function, current_location, and
+    %% current_stacktrace give sane results flushing or not...
+    Self = self(),
+    pi_sig_spam_test(fun () ->
+                             process_info_self_msgq_len_spammer(Self)
+                     end,
+                     fun process_info_self_msgq_len_more_caller_body/0,
+                     fun process_info_self_msgq_len_more_caller_body_result/1),
+    pi_sig_spam_test(fun () ->
+                             process_info_self_msgq_len_spammer(Self)
+                     end,
+                     fun process_info_self_msgq_len_more_caller_tail/0,
+                     fun process_info_self_msgq_len_more_caller_tail_result/1).
+
+process_info_self_msgq_len_more_caller_body() ->
+    Res = process_info(self(),
+                       [message_queue_len,
+                        current_function,
+                        current_location,
+                        current_stacktrace]),
+    id(Res).
+
+process_info_self_msgq_len_more_caller_body_result(Res) ->
+    [{message_queue_len, Len},
+     {current_function, {process_SUITE,process_info_self_msgq_len_more_caller_body,0}},
+     {current_location, {process_SUITE,process_info_self_msgq_len_more_caller_body,0,_}},
+     {current_stacktrace,
+      [{process_SUITE,process_info_self_msgq_len_more_caller_body,0,_} | _]}] = Res,
+    true = Len > 0,
+    ok.
+
+process_info_self_msgq_len_more_caller_tail() ->
+    process_info(self(),
+                 [message_queue_len,
+                  current_function,
+                  current_location,
+                  current_stacktrace]).
+
+process_info_self_msgq_len_more_caller_tail_result(Res) ->
+    [{message_queue_len, Len},
+     {current_function, {process_SUITE,process_info_self_msgq_len_more_caller_tail,0}},
+     {current_location, {process_SUITE,process_info_self_msgq_len_more_caller_tail,0,_}},
+     {current_stacktrace,
+      [{process_SUITE,process_info_self_msgq_len_more_caller_tail,0,_} | _]}] = Res,
+    true = Len > 0,
+    ok.
+    
+
+process_info_self_msgq_len_spammer(To) ->
+    process_info_self_msgq_len_spammer(To, 10000000).
+
+process_info_self_msgq_len_spammer(_To, 0) ->
+    ok;
+process_info_self_msgq_len_spammer(To, N) ->
+    To ! hejhopp,
+    erlang:demonitor(erlang:monitor(process, To)),
+    process_info_self_msgq_len_spammer(To, N-1).
+
+pi_sig_spam_test(SpamFun, PITest, PICheckRes) ->
+    SO = erlang:system_flag(schedulers_online, 1),
+    try
+        Self = self(),
+        SigSpammer = spawn_link(SpamFun),
+        process_flag(priority, low),
+        receive after 10 -> ok end,
+        Res = PITest(),
+        process_flag(priority, high),
+        unlink(SigSpammer),
+        exit(SigSpammer, kill),
+        false = is_process_alive(SigSpammer),
+        PICheckRes(Res)
+    after
+        _ = erlang:system_flag(schedulers_online, SO)
+    end.
+    
 
 %% Tests erlang:bump_reductions/1.
 bump_reductions(Config) when is_list(Config) ->
diff --git a/erts/etc/unix/etp-commands.in b/erts/etc/unix/etp-commands.in
index fa215618aa..64d8de67df 100644
--- a/erts/etc/unix/etp-commands.in
+++ b/erts/etc/unix/etp-commands.in
@@ -2479,7 +2479,7 @@ define etp-proc-state-int
     printf "active | "
   end
   if ($arg0 & 0x1000)
-    printf "unused | "
+    printf "maybe-self-sigs | "
   end
   if ($arg0 & 0x800)
     printf "exiting | "
-- 
2.35.3

Places

File 4031-erts-Improve-flushing-of-signals.patch of Package erlang (Revision 01b3dc6452ffd94552aa8e1bbc0ff8ba)

Places