Merge branch 'rickard/process_info/OTP-14966'

* rickard/process_info/OTP-14966:
  New process_info() implementation using signals

22 files changed, 1981 insertions, 961 deletions

diff --git a/erts/emulator/beam/beam_emu.c b/erts/emulator/beam/beam_emu.c
index fb87be3f17..ee287243a4 100644
--- a/erts/emulator/beam/beam_emu.c
+++ b/erts/emulator/beam/beam_emu.c
@@ -2420,8 +2420,7 @@ erts_hibernate(Process* c_p, Eterm* reg)
      * shrink the heap. 
      */
     erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS);
-    erts_proc_sig_fetch(c_p);
-    if (!c_p->sig_qs.len) {
+    if (!erts_proc_sig_fetch(c_p)) {
 	erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS);
 	c_p->fvalue = NIL;
 	PROCESS_MAIN_CHK_LOCKS(c_p);
@@ -2429,8 +2428,7 @@ erts_hibernate(Process* c_p, Eterm* reg)
 	ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
 	PROCESS_MAIN_CHK_LOCKS(c_p);
 	erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS);
-        erts_proc_sig_fetch(c_p);
-	if (!c_p->sig_qs.len)
+	if (!erts_proc_sig_fetch(c_p))
 	    erts_atomic32_read_band_relb(&c_p->state, ~ERTS_PSFLG_ACTIVE);
 	ASSERT(!ERTS_PROC_IS_EXITING(c_p));
     }
diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 232597c5b6..017faffa48 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -4147,7 +4147,8 @@ BIF_RETTYPE erts_internal_group_leader_2(BIF_ALIST_2)
             rp = BIF_P;
         else {
             rp = erts_try_lock_sig_free_proc(BIF_ARG_2,
-                                             ERTS_PROC_LOCK_MAIN);
+                                             ERTS_PROC_LOCK_MAIN,
+                                             NULL);
             if (!rp)
                 BIF_RET(am_badarg);
             if (rp == ERTS_PROC_LOCK_BUSY)
diff --git a/erts/emulator/beam/bif.h b/erts/emulator/beam/bif.h
index a33421d762..a47339253e 100644
--- a/erts/emulator/beam/bif.h
+++ b/erts/emulator/beam/bif.h
@@ -425,6 +425,12 @@ do {									\
     BIF_TRAP3((TRP), (P), (A0), (A1), (A2));				\
 } while (0)
 
+#define ERTS_BIF_PREP_EXITED(RET, PROC)	                                \
+do {                                                                    \
+    KILL_CATCHES((PROC));                                               \
+    ERTS_BIF_PREP_ERROR((RET), (PROC), EXTAG_EXIT);                     \
+} while (0)
+
 #define ERTS_BIF_EXITED(PROC)		\
 do {					\
     KILL_CATCHES((PROC));		\
diff --git a/erts/emulator/beam/binary.c b/erts/emulator/beam/binary.c
index 95d324d2c1..d53f75c279 100644
--- a/erts/emulator/beam/binary.c
+++ b/erts/emulator/beam/binary.c
@@ -113,6 +113,40 @@ new_binary(Process *p, byte *buf, Uint len)
     return build_proc_bin(&MSO(p), HAlloc(p, PROC_BIN_SIZE), bptr);
 }
 
+Eterm
+erts_heap_factory_new_binary(ErtsHeapFactory *hfact, byte *buf, Uint len,
+                             Uint reserve_size)
+{
+    Eterm *hp;
+    Binary* bptr;
+
+    if (len <= ERL_ONHEAP_BIN_LIMIT) {
+	ErlHeapBin* hb;
+        hp = erts_produce_heap(hfact, heap_bin_size(len), reserve_size);
+        hb = (ErlHeapBin *) hp;
+	hb->thing_word = header_heap_bin(len);
+	hb->size = len;
+	if (buf != NULL) {
+	    sys_memcpy(hb->data, buf, len);
+	}
+	return make_binary(hb);
+    }
+
+    /*
+     * Allocate the binary struct itself.
+     */
+    bptr = erts_bin_nrml_alloc(len);
+    if (buf != NULL) {
+	sys_memcpy(bptr->orig_bytes, buf, len);
+    }
+
+    hp = erts_produce_heap(hfact, PROC_BIN_SIZE, reserve_size);
+
+    return build_proc_bin(hfact->off_heap, hp, bptr);
+}
+
+
+
 /* 
  * When heap binary is not desired...
  */
diff --git a/erts/emulator/beam/break.c b/erts/emulator/beam/break.c
index 4dabac3512..ba8cc5e2ba 100644
--- a/erts/emulator/beam/break.c
+++ b/erts/emulator/beam/break.c
@@ -204,6 +204,7 @@ print_process_info(fmtfn_t to, void *to_arg, Process *p)
 {
     int garbing = 0;
     int running = 0;
+    Sint len;
     struct saved_calls *scb;
     erts_aint32_t state;
 
@@ -252,9 +253,9 @@ print_process_info(fmtfn_t to, void *to_arg, Process *p)
     erts_print(to, to_arg, "Spawned by: %T\n", p->parent);
 
     erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
-    erts_proc_sig_fetch(p);
+    len = erts_proc_sig_fetch(p);
     erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
-    erts_print(to, to_arg, "Message queue length: %d\n", p->sig_qs.len);
+    erts_print(to, to_arg, "Message queue length: %d\n", len);
 
     /* display the message queue only if there is anything in it */
     if (!ERTS_IS_CRASH_DUMPING && p->sig_qs.first != NULL && !garbing) {
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index bdca93428e..d443e12409 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -155,8 +155,10 @@ static Eterm os_type_tuple;
 static Eterm os_version_tuple;
 
 static Eterm
-current_function(Process* p, Process* rp, Eterm** hpp, int full_info);
-static Eterm current_stacktrace(Process* p, Process* rp, Eterm** hpp);
+current_function(Process* p, ErtsHeapFactory *hfact, Process* rp,
+                 int full_info, Uint reserve_size, int flags);
+static Eterm current_stacktrace(ErtsHeapFactory *hfact, Process* rp,
+                                Uint reserve_size);
 
 static Eterm
 bld_bin_list(Uint **hpp, Uint *szp, ErlOffHeap* oh)
@@ -693,119 +695,222 @@ collect_one_suspend_monitor(ErtsMonitor *mon, void *vsmicp)
  * process_info/[1,2]
  */
 
-#define ERTS_PI_FAIL_TYPE_BADARG		0
-#define ERTS_PI_FAIL_TYPE_YIELD			1
-#define ERTS_PI_FAIL_TYPE_EXITED                2
-
-static ERTS_INLINE ErtsProcLocks
-pi_locks(Eterm info)
-{
-    switch (info) {
-    case am_priority:
-    case am_status:
-        return 0;
-    case am_suspended:
-        return ERTS_PROC_LOCK_STATUS;
-    case am_messages:
-    case am_message_queue_len:
-    case am_total_heap_size:
-        return ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_MSGQ;
-    default:
-        return ERTS_PROC_LOCK_MAIN;
-    }
-}
-
 /*
  * All valid process_info arguments.
  */
-static Eterm pi_args[] = {
-    am_registered_name,
-    am_current_function,
-    am_initial_call,
-    am_status,
-    am_messages,
-    am_message_queue_len,
-    am_links,
-    am_monitors,
-    am_monitored_by,
-    am_dictionary,
-    am_trap_exit,
-    am_error_handler,
-    am_heap_size,
-    am_stack_size,
-    am_memory,
-    am_garbage_collection,
-    am_group_leader,
-    am_reductions,
-    am_priority,
-    am_trace,
-    am_binary,
-    am_sequential_trace_token,
-    am_catchlevel,
-    am_backtrace,
-    am_last_calls,
-    am_total_heap_size,
-    am_suspending,
-    am_min_heap_size,
-    am_min_bin_vheap_size,
-    am_max_heap_size,
-    am_current_location,
-    am_current_stacktrace,
-    am_message_queue_data,
-    am_garbage_collection_info,
-    am_magic_ref
+
+#define ERTS_PI_IX_REGISTERED_NAME                      0
+#define ERTS_PI_IX_CURRENT_FUNCTION                     1
+#define ERTS_PI_IX_INITIAL_CALL                         2
+#define ERTS_PI_IX_STATUS                               3
+#define ERTS_PI_IX_MESSAGES                             4
+#define ERTS_PI_IX_MESSAGE_QUEUE_LEN                    5
+#define ERTS_PI_IX_LINKS                                6
+#define ERTS_PI_IX_MONITORS                             7
+#define ERTS_PI_IX_MONITORED_BY                         8
+#define ERTS_PI_IX_DICTIONARY                           9
+#define ERTS_PI_IX_TRAP_EXIT                            10
+#define ERTS_PI_IX_ERROR_HANDLER                        11
+#define ERTS_PI_IX_HEAP_SIZE                            12
+#define ERTS_PI_IX_STACK_SIZE                           13
+#define ERTS_PI_IX_MEMORY                               14
+#define ERTS_PI_IX_GARBAGE_COLLECTION                   15
+#define ERTS_PI_IX_GROUP_LEADER                         16
+#define ERTS_PI_IX_REDUCTIONS                           17
+#define ERTS_PI_IX_PRIORITY                             18
+#define ERTS_PI_IX_TRACE                                19
+#define ERTS_PI_IX_BINARY                               20
+#define ERTS_PI_IX_SEQUENTIAL_TRACE_TOKEN               21
+#define ERTS_PI_IX_CATCHLEVEL                           22
+#define ERTS_PI_IX_BACKTRACE                            23
+#define ERTS_PI_IX_LAST_CALLS                           24
+#define ERTS_PI_IX_TOTAL_HEAP_SIZE                      25
+#define ERTS_PI_IX_SUSPENDING                           26
+#define ERTS_PI_IX_MIN_HEAP_SIZE                        27
+#define ERTS_PI_IX_MIN_BIN_VHEAP_SIZE                   28
+#define ERTS_PI_IX_MAX_HEAP_SIZE                        29
+#define ERTS_PI_IX_CURRENT_LOCATION                     30
+#define ERTS_PI_IX_CURRENT_STACKTRACE                   31
+#define ERTS_PI_IX_MESSAGE_QUEUE_DATA                   32
+#define ERTS_PI_IX_GARBAGE_COLLECTION_INFO              33
+#define ERTS_PI_IX_MAGIC_REF                            34
+#define ERTS_PI_IX_FULLSWEEP_AFTER                      35
+
+#define ERTS_PI_FLAG_SINGELTON                          (1 << 0)
+#define ERTS_PI_FLAG_ALWAYS_WRAP                        (1 << 1)
+#define ERTS_PI_FLAG_WANT_MSGS                          (1 << 2)
+#define ERTS_PI_FLAG_NEED_MSGQ_LEN                      (1 << 3)
+#define ERTS_PI_FLAG_FORCE_SIG_SEND                     (1 << 4)
+#define ERTS_PI_FLAG_REQUEST_FOR_OTHER                  (1 << 5)
+
+#define ERTS_PI_UNRESERVE(RS, SZ) \
+    (ASSERT((RS) >= (SZ)), (RS) -= (SZ))
+
+
+typedef struct {
+    Eterm name;
+    Uint reserve_size;
+    int flags;
+    ErtsProcLocks locks;
+} ErtsProcessInfoArgs;
+
+static ErtsProcessInfoArgs pi_args[] = {
+    {am_registered_name, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_current_function, 4, 0, ERTS_PROC_LOCK_MAIN},
+    {am_initial_call, 4, 0, ERTS_PROC_LOCK_MAIN},
+    {am_status, 0, 0, 0},
+    {am_messages, 0, ERTS_PI_FLAG_WANT_MSGS|ERTS_PI_FLAG_NEED_MSGQ_LEN|ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_message_queue_len, 0, ERTS_PI_FLAG_NEED_MSGQ_LEN, ERTS_PROC_LOCK_MAIN},
+    {am_links, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_monitors, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_monitored_by, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_dictionary, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_trap_exit, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_error_handler, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_heap_size, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_stack_size, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_memory, 0, ERTS_PI_FLAG_NEED_MSGQ_LEN|ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_garbage_collection, 3+2 + 3+2 + 3+2 + 3+2 + 3+2 + ERTS_MAX_HEAP_SIZE_MAP_SZ, 0, ERTS_PROC_LOCK_MAIN},
+    {am_group_leader, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_reductions, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_priority, 0, 0, 0},
+    {am_trace, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_binary, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_sequential_trace_token, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_catchlevel, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_backtrace, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_last_calls, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_total_heap_size, 0, ERTS_PI_FLAG_NEED_MSGQ_LEN|ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_suspending, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, 0},
+    {am_min_heap_size, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_min_bin_vheap_size, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_max_heap_size, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_current_location, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_current_stacktrace, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_message_queue_data, 0, 0, ERTS_PROC_LOCK_MAIN},
+    {am_garbage_collection_info, ERTS_PROCESS_GC_INFO_MAX_SIZE, 0, ERTS_PROC_LOCK_MAIN},
+    {am_magic_ref, 0, ERTS_PI_FLAG_FORCE_SIG_SEND, ERTS_PROC_LOCK_MAIN},
+    {am_fullsweep_after, 0, 0, ERTS_PROC_LOCK_MAIN}
 };
 
-#define ERTS_PI_ARGS ((int) (sizeof(pi_args)/sizeof(Eterm)))
+#define ERTS_PI_ARGS ((int) (sizeof(pi_args)/sizeof(pi_args[0])))
+
+#ifdef DEBUG
+#  define ERTS_PI_DEF_ARR_SZ 2
+#else
+#  define ERTS_PI_DEF_ARR_SZ ERTS_PI_ARGS
+#endif
 
 static ERTS_INLINE Eterm
 pi_ix2arg(int ix)
 {
     if (ix < 0 || ERTS_PI_ARGS <= ix)
 	return am_undefined;
-    return pi_args[ix];
+    return pi_args[ix].name;
+}
+
+static ERTS_INLINE int
+pi_ix2flags(int ix)
+{
+    if (ix < 0 || ERTS_PI_ARGS <= ix)
+	return 0;
+    return pi_args[ix].flags;
+}
+
+static ERTS_INLINE Uint
+pi_ix2rsz(int ix)
+{
+    if (ix < 0 || ERTS_PI_ARGS <= ix)
+	return 0;
+    return pi_args[ix].reserve_size;
+}
+
+static ERTS_INLINE ErtsProcLocks
+pi_ix2locks(int ix)
+{
+    if (ix < 0 || ERTS_PI_ARGS <= ix)
+	return 0;
+    return pi_args[ix].locks;
 }
 
 static ERTS_INLINE int
 pi_arg2ix(Eterm arg)
 {
     switch (arg) {
-    case am_registered_name:			return 0;
-    case am_current_function:			return 1;
-    case am_initial_call:			return 2;
-    case am_status:				return 3;
-    case am_messages:				return 4;
-    case am_message_queue_len:			return 5;
-    case am_links:				return 6;
-    case am_monitors:				return 7;
-    case am_monitored_by:			return 8;
-    case am_dictionary:				return 9;
-    case am_trap_exit:				return 10;
-    case am_error_handler:			return 11;
-    case am_heap_size:				return 12;
-    case am_stack_size:				return 13;
-    case am_memory:				return 14;
-    case am_garbage_collection:			return 15;
-    case am_group_leader:			return 16;
-    case am_reductions:				return 17;
-    case am_priority:				return 18;
-    case am_trace:				return 19;
-    case am_binary:				return 20;
-    case am_sequential_trace_token:		return 21;
-    case am_catchlevel:				return 22;
-    case am_backtrace:				return 23;
-    case am_last_calls:				return 24;
-    case am_total_heap_size:			return 25;
-    case am_suspending:				return 26;
-    case am_min_heap_size:			return 27;
-    case am_min_bin_vheap_size:			return 28;
-    case am_max_heap_size:			return 29;
-    case am_current_location:			return 30;
-    case am_current_stacktrace:			return 31;
-    case am_message_queue_data:			return 32;
-    case am_garbage_collection_info:		return 33;
-    case am_magic_ref:                          return 34;
-    default:					return -1;
+    case am_registered_name:
+        return ERTS_PI_IX_REGISTERED_NAME;
+    case am_current_function:
+        return ERTS_PI_IX_CURRENT_FUNCTION;
+    case am_initial_call:
+        return ERTS_PI_IX_INITIAL_CALL;
+    case am_status:
+        return ERTS_PI_IX_STATUS;
+    case am_messages:
+        return ERTS_PI_IX_MESSAGES;
+    case am_message_queue_len:
+        return ERTS_PI_IX_MESSAGE_QUEUE_LEN;
+    case am_links:
+        return ERTS_PI_IX_LINKS;
+    case am_monitors:
+        return ERTS_PI_IX_MONITORS;
+    case am_monitored_by:
+        return ERTS_PI_IX_MONITORED_BY;
+    case am_dictionary:
+        return ERTS_PI_IX_DICTIONARY;
+    case am_trap_exit:
+        return ERTS_PI_IX_TRAP_EXIT;
+    case am_error_handler:
+        return ERTS_PI_IX_ERROR_HANDLER;
+    case am_heap_size:
+        return ERTS_PI_IX_HEAP_SIZE;
+    case am_stack_size:
+        return ERTS_PI_IX_STACK_SIZE;
+    case am_memory:
+        return ERTS_PI_IX_MEMORY;
+    case am_garbage_collection:
+        return ERTS_PI_IX_GARBAGE_COLLECTION;
+    case am_group_leader:
+        return ERTS_PI_IX_GROUP_LEADER;
+    case am_reductions:
+        return ERTS_PI_IX_REDUCTIONS;
+    case am_priority:
+        return ERTS_PI_IX_PRIORITY;
+    case am_trace:
+        return ERTS_PI_IX_TRACE;
+    case am_binary:
+        return ERTS_PI_IX_BINARY;
+    case am_sequential_trace_token:
+        return ERTS_PI_IX_SEQUENTIAL_TRACE_TOKEN;
+    case am_catchlevel:
+        return ERTS_PI_IX_CATCHLEVEL;
+    case am_backtrace:
+        return ERTS_PI_IX_BACKTRACE;
+    case am_last_calls:
+        return ERTS_PI_IX_LAST_CALLS;
+    case am_total_heap_size:
+        return ERTS_PI_IX_TOTAL_HEAP_SIZE;
+    case am_suspending:
+        return ERTS_PI_IX_SUSPENDING;
+    case am_min_heap_size:
+        return ERTS_PI_IX_MIN_HEAP_SIZE;
+    case am_min_bin_vheap_size:
+        return ERTS_PI_IX_MIN_BIN_VHEAP_SIZE;
+    case am_max_heap_size:
+        return ERTS_PI_IX_MAX_HEAP_SIZE;
+    case am_current_location:
+        return ERTS_PI_IX_CURRENT_LOCATION;
+    case am_current_stacktrace:
+        return ERTS_PI_IX_CURRENT_STACKTRACE;
+    case am_message_queue_data:
+        return ERTS_PI_IX_MESSAGE_QUEUE_DATA;
+    case am_garbage_collection_info:
+	return ERTS_PI_IX_GARBAGE_COLLECTION_INFO;
+    case am_magic_ref:
+        return ERTS_PI_IX_MAGIC_REF;
+    case am_fullsweep_after:
+        return ERTS_PI_IX_FULLSWEEP_AFTER;
+    default:
+        return -1;
     }
 }
 
@@ -858,186 +963,41 @@ process_info_init(void)
 
 }
 
-static ERTS_INLINE Process *
-pi_lookup_proc(Process *c_p, Eterm pid, ErtsProcLocks *locks)
-{
-    /*
-     * If the main lock is needed, we use erts_pid2proc_not_running()
-     * instead of erts_pid2proc() for two reasons:
-     * * Current function of pid and possibly other information will
-     *   have been updated so that process_info() is consistent with an
-     *   info-request/info-response signal model.
-     * * We avoid blocking the whole scheduler executing the
-     *   process that is calling process_info() for a long time
-     *   which will happen if pid is currently running.
-     * The caller of process_info() may have to yield if pid
-     * is currently running.
-     */
-
-    if ((*locks) & ERTS_PROC_LOCK_MAIN) {
-        erts_aint32_t state;
-        int local_only, done;
-        Process *rp;
-        ErtsProcLocks more_locks;
-
-        rp = erts_pid2proc_not_running(c_p, ERTS_PROC_LOCK_MAIN,
-                                       pid, ERTS_PROC_LOCK_MAIN);
-
-        if (!rp || rp == ERTS_PROC_LOCK_BUSY)
-            return rp;
-
-        if ((*locks) & ERTS_PROC_LOCK_MSGQ) {
-            /*
-             * Move in queue into private queue and
-             * release msgq lock, enabling others to
-             * send messages to the process while it
-             * is being inspected...
-             */
-            erts_proc_lock(rp, ERTS_PROC_LOCK_MSGQ);
-            erts_proc_sig_fetch(rp);
-            erts_proc_unlock(rp, ERTS_PROC_LOCK_MSGQ);
-            (*locks) &= ~ERTS_PROC_LOCK_MSGQ;
-	}
-
-        /*
-         * Handle all signals received up to this point
-         * in order to preserve signal order.
-         * 
-         * FIX ME: Should be done yielding...
-         */
-        local_only = 0;
-        do {
-            int r = CONTEXT_REDS;
-            done = erts_proc_sig_handle_incoming(rp, &state, &r,
-                                                 CONTEXT_REDS,
-                                                 local_only);
-            local_only = !0;
-            BUMP_REDS(c_p, r);
-        } while (!done && !(state & ERTS_PSFLG_EXITING));
-
-        if (state & ERTS_PSFLG_EXITING) {
-            if (rp != c_p)
-                erts_proc_unlock(rp, ERTS_PROC_LOCK_MAIN);
-            return NULL;
-        }
-        more_locks = (*locks) & ~ERTS_PROC_LOCK_MAIN;
-        if (more_locks)
-            erts_proc_lock(rp, more_locks);
-        return rp;
-    }
-
-    ASSERT(!((*locks) & ERTS_PROC_LOCK_MSGQ));
-
-    if (*locks)
-        return erts_pid2proc(c_p, ERTS_PROC_LOCK_MAIN,
-			     pid, *locks);
-
-    return erts_proc_lookup(pid);
-}
-
-
-
-
-
 static BIF_RETTYPE
-process_info_aux(Process *BIF_P,
+process_info_aux(Process *c_p,
+                 ErtsHeapFactory *hfact,
 		 Process *rp,
 		 ErtsProcLocks rp_locks,
-		 Eterm rpid,
-		 Eterm item,
-		 int always_wrap,
-                 int *reds);
-
-#define ERTS_PI_RES_ELEM_IX_BUF_INC 1024
-#define ERTS_PI_DEF_RES_ELEM_IX_BUF_SZ ERTS_PI_ARGS
+		 int item_ix,
+		 int flags,
+                 Uint *reserve_sizep,
+                 Uint *reds);
 
-static Eterm
-process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
-		  int *fail_type)
+Eterm
+erts_process_info(Process *c_p,
+                  ErtsHeapFactory *hfact,
+                  Process *rp,
+                  ErtsProcLocks rp_locks,
+                  int *item_ix,
+                  int item_ix_len,
+                  int flags,
+                  Uint reserve_size,
+                  Uint *reds)
 {
-    int want_messages = 0;
-    int def_res_elem_ix_buf[ERTS_PI_DEF_RES_ELEM_IX_BUF_SZ];
-    int *res_elem_ix = &def_res_elem_ix_buf[0];
-    int res_elem_ix_ix = -1;
-    int res_elem_ix_sz = ERTS_PI_DEF_RES_ELEM_IX_BUF_SZ;
+    Eterm res;
     Eterm part_res[ERTS_PI_ARGS];
-    Eterm res, arg;
-    Uint *hp, *hp_end;
-    ErtsProcLocks locks = (ErtsProcLocks) 0;
-    int res_len, ix;
-    Process *rp = NULL;
-    int reds = 0;
+    int item_ix_ix, ix;
 
-    *fail_type = ERTS_PI_FAIL_TYPE_BADARG;
+    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);
+        return res;
+    }
 
     for (ix = 0; ix < ERTS_PI_ARGS; ix++)
 	part_res[ix] = THE_NON_VALUE;
 
-    ASSERT(is_list(list));
-
-    while (is_list(list)) {
-	Eterm* consp = list_val(list);
-
-	arg = CAR(consp);
-	ix = pi_arg2ix(arg);
-	if (ix < 0) {
-	    res = THE_NON_VALUE;
-	    goto done;
-	}
-	if (arg == am_messages)
-	    want_messages = 1;
-	locks |= pi_locks(arg);
-	res_elem_ix_ix++;
-	if (res_elem_ix_ix >= res_elem_ix_sz) {
-	    if (res_elem_ix != &def_res_elem_ix_buf[0])
-		res_elem_ix =
-		    erts_realloc(ERTS_ALC_T_TMP,
-				 res_elem_ix,
-				 sizeof(int)*(res_elem_ix_sz
-					      += ERTS_PI_RES_ELEM_IX_BUF_INC));
-	    else {
-		int new_res_elem_ix_sz = ERTS_PI_RES_ELEM_IX_BUF_INC;
-		int *new_res_elem_ix = erts_alloc(ERTS_ALC_T_TMP,
-						  sizeof(int)*new_res_elem_ix_sz);
-		sys_memcpy((void *) new_res_elem_ix,
-			   (void *) res_elem_ix,
-			   sizeof(int)*res_elem_ix_sz);
-		res_elem_ix = new_res_elem_ix;
-		res_elem_ix_sz = new_res_elem_ix_sz;
-	    }
-	}
-	res_elem_ix[res_elem_ix_ix] = ix;
-	list = CDR(consp);
-    }
-    if (is_not_nil(list)) {
-	res = THE_NON_VALUE;
-	goto done;
-    }
-
-    res_len = res_elem_ix_ix+1;
-
-    ASSERT(res_len > 0);
-
-    rp = pi_lookup_proc(c_p, pid, &locks);
-    if (!rp) {
-        if (c_p->common.id != pid)
-            res = am_undefined;
-        else {
-            *fail_type = ERTS_PI_FAIL_TYPE_EXITED;
-            res = THE_NON_VALUE;
-        }
-	goto done;
-    }
-    else if (rp == ERTS_PROC_LOCK_BUSY) {
-	rp = NULL;
-	res = THE_NON_VALUE;
-	*fail_type = ERTS_PI_FAIL_TYPE_YIELD;
-	goto done;
-    }
-
-    if (c_p == rp)
-        locks |= ERTS_PROC_LOCK_MAIN;
-
     /*
      * We always handle 'messages' first if it should be part
      * of the result. This since if both 'messages' and
@@ -1045,35 +1005,31 @@ process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
      * change the result of 'message_queue_len' (in case
      * the queue contain bad distribution messages).
      */
-    if (want_messages) {
+    if (flags & ERTS_PI_FLAG_WANT_MSGS) {
 	ix = pi_arg2ix(am_messages);
 	ASSERT(part_res[ix] == THE_NON_VALUE);
-	res = process_info_aux(c_p, rp, locks, pid, am_messages,
-                               always_wrap, &reds);
+	res = process_info_aux(c_p, hfact, rp, rp_locks, ix,
+                               flags, &reserve_size, reds);
 	ASSERT(res != am_undefined);
 	ASSERT(res != THE_NON_VALUE);
         part_res[ix] = res;
     }
 
-    for (; res_elem_ix_ix >= 0; res_elem_ix_ix--) {
-	ix = res_elem_ix[res_elem_ix_ix];
+    for (item_ix_ix = item_ix_len - 1; item_ix_ix >= 0; item_ix_ix--) {
+	ix = item_ix[item_ix_ix];
 	if (part_res[ix] == THE_NON_VALUE) {
-	    arg = pi_ix2arg(ix);
-	    res = process_info_aux(c_p, rp, locks, pid, arg,
-                                   always_wrap, &reds);
-            if (res == am_undefined)
-                goto done;
+	    res = process_info_aux(c_p, hfact, rp, rp_locks, ix,
+                                   flags, &reserve_size, reds);
+            ASSERT(res != am_undefined);
 	    ASSERT(res != THE_NON_VALUE);
             part_res[ix] = res;
 	}
     }
 
-    hp = HAlloc(c_p, res_len*2);
-    hp_end = hp + res_len*2;
     res = NIL;
 
-    for (res_elem_ix_ix = res_len - 1; res_elem_ix_ix >= 0; res_elem_ix_ix--) {
-	ix = res_elem_ix[res_elem_ix_ix];
+    for (item_ix_ix = item_ix_len - 1; item_ix_ix >= 0; item_ix_ix--) {
+	ix = item_ix[item_ix_ix];
 	ASSERT(part_res[ix] != THE_NON_VALUE);
 	/*
 	 * If we should ignore the value of registered_name,
@@ -1081,155 +1037,310 @@ process_info_list(Process *c_p, Eterm pid, Eterm list, int always_wrap,
 	 * beginning of process_info_aux().
 	 */
 	if (is_nil(part_res[ix])) {
-	    ASSERT(!always_wrap);
+	    ASSERT(!(flags & ERTS_PI_FLAG_ALWAYS_WRAP));
 	    ASSERT(pi_ix2arg(ix) == am_registered_name);
 	}
 	else {
+            Eterm *hp;
+            ERTS_PI_UNRESERVE(reserve_size, 2);
+            hp = erts_produce_heap(hfact, 2, reserve_size);
 	    res = CONS(hp, part_res[ix], res);
-	    hp += 2;
 	}
     }
 
-    if (!always_wrap) {
-	HRelease(c_p, hp_end, hp);
-    }
+    return res;
+}
 
- done:
+static void
+pi_setup_grow(int **arr, int *def_arr, Uint *sz, int ix);
 
-    if (c_p == rp)
-	locks &= ~ERTS_PROC_LOCK_MAIN;
-    if (locks && rp)
-	erts_proc_unlock(rp, locks);
+static BIF_RETTYPE
+process_info_bif(Process *c_p, Eterm pid, Eterm opt, int always_wrap, int pi2)
+{
+    ErtsHeapFactory hfact;
+    int def_arr[ERTS_PI_DEF_ARR_SZ];
+    int *item_ix = &def_arr[0];
+    Process *rp = NULL;
+    erts_aint32_t state;
+    BIF_RETTYPE ret;
+    Uint reds = 0;
+    ErtsProcLocks locks = 0;
+    int flags;
+    Uint reserve_size;
+    int len;
+    Eterm res;
 
-    if (res_elem_ix != &def_res_elem_ix_buf[0])
-	erts_free(ERTS_ALC_T_TMP, res_elem_ix);
+    ERTS_CT_ASSERT(ERTS_PI_DEF_ARR_SZ > 0);
 
-    BUMP_REDS(c_p, reds);
+    if (c_p->common.id == pid) {
+        int local_only = c_p->flags & F_LOCAL_SIGS_ONLY;
+        int sreds = ERTS_BIF_REDS_LEFT(c_p);
+        int sres;
 
-    return res;
-}
+        if (!local_only) {
+            erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
+            erts_proc_sig_fetch(c_p);
+            erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+        }
 
-BIF_RETTYPE process_info_1(BIF_ALIST_1)
-{
-    Eterm res;
-    int fail_type;
+        sres = erts_proc_sig_handle_incoming(c_p, &state, &sreds, sreds, !0);
+        if (state & ERTS_PSFLG_EXITING) {
+            c_p->flags &= ~F_LOCAL_SIGS_ONLY;
+            goto exited;
+        }
+        if (!sres) {
+            /*
+             * More signals to handle; need to yield and continue.
+             * Prevent fetching of more signals by setting
+             * local-sigs-only flag.
+             */
+            c_p->flags |= F_LOCAL_SIGS_ONLY;
+            goto yield;
+        }
 
-    if (is_external_pid(BIF_ARG_1)
-	&& external_pid_dist_entry(BIF_ARG_1) == erts_this_dist_entry)
-	BIF_RET(am_undefined);
-	
-    if (is_not_internal_pid(BIF_ARG_1)) {
-	BIF_ERROR(BIF_P, BADARG);
-    }
-
-    res = process_info_list(BIF_P, BIF_ARG_1, pi_1_keys_list, 0, &fail_type);
-    if (is_non_value(res)) {
-	switch (fail_type) {
-	case ERTS_PI_FAIL_TYPE_BADARG:
-	    BIF_ERROR(BIF_P, BADARG);
-	case ERTS_PI_FAIL_TYPE_YIELD:
-	    ERTS_BIF_YIELD1(bif_export[BIF_process_info_1], BIF_P, BIF_ARG_1);
-        case ERTS_PI_FAIL_TYPE_EXITED:
-            ERTS_BIF_EXITED(BIF_P);
-	default:
-	    erts_exit(ERTS_ABORT_EXIT, "%s:%d: Internal error", __FILE__, __LINE__);
-	}
+        c_p->flags &= ~F_LOCAL_SIGS_ONLY;
     }
 
-    ASSERT(!(BIF_P->flags & F_P2PNR_RESCHED));
-    BIF_RET(res);
-}
+    if (is_atom(opt)) {
+	int ix = pi_arg2ix(opt);
+        item_ix[0] = ix;
+        len = 1;
+        locks = pi_ix2locks(ix);
+        reserve_size = 3 + pi_ix2rsz(ix);
+        flags = ERTS_PI_FLAG_SINGELTON;
+        flags |= pi_ix2flags(ix);
+        if (ix < 0)
+            goto badarg;
+    }
+    else {
+        Eterm list = opt;
+        Uint size = ERTS_PI_DEF_ARR_SZ;
 
+        len = 0;
+        reserve_size = 0;
+        locks = 0;
+        flags = 0;
 
-BIF_RETTYPE process_info_2(BIF_ALIST_2) 
-{
-    Eterm res;
-    Process *rp;
-    Eterm pid = BIF_ARG_1;
-    ErtsProcLocks info_locks;
-    int fail_type, reds = 0;
+        while (is_list(list)) {
+            Eterm *consp = list_val(list);
+            Eterm arg = CAR(consp);
+            int ix = pi_arg2ix(arg);
+            if (ix < 0)
+                goto badarg;
+
+            if (len >= size)
+                pi_setup_grow(&item_ix, def_arr, &size, len);
+
+            item_ix[len++] = ix;
+
+            locks |= pi_ix2locks(ix);
+            flags |= pi_ix2flags(ix);
+            reserve_size += pi_ix2rsz(ix);
+            reserve_size += 3; /* 2-tuple */
+            reserve_size += 2; /* cons */
+
+            list = CDR(consp);
+        }
+
+        if (is_not_nil(list))
+            goto badarg;
+    }
 
-    if (is_external_pid(pid)
-	&& external_pid_dist_entry(pid) == erts_this_dist_entry)
-	BIF_RET(am_undefined);
-	
     if (is_not_internal_pid(pid)) {
-	BIF_ERROR(BIF_P, BADARG);
+        if (is_external_pid(pid)
+            && external_pid_dist_entry(pid) == erts_this_dist_entry)
+            goto undefined;
+        goto badarg;
     }
 
-    if (is_nil(BIF_ARG_2))
-	BIF_RET(NIL);
+    if (always_wrap)
+        flags |= ERTS_PI_FLAG_ALWAYS_WRAP;
 
-    if (is_list(BIF_ARG_2)) {
-	res = process_info_list(BIF_P, BIF_ARG_1, BIF_ARG_2, 1, &fail_type);
-	if (is_non_value(res)) {
-	    switch (fail_type) {
-	    case ERTS_PI_FAIL_TYPE_BADARG:
-		BIF_ERROR(BIF_P, BADARG);
-	    case ERTS_PI_FAIL_TYPE_YIELD:
-		ERTS_BIF_YIELD2(bif_export[BIF_process_info_2], BIF_P,
-				BIF_ARG_1, BIF_ARG_2);
-            case ERTS_PI_FAIL_TYPE_EXITED:
-                ERTS_BIF_EXITED(BIF_P);
-	    default:
-		erts_exit(ERTS_ABORT_EXIT, "%s:%d: Internal error",
-			 __FILE__, __LINE__);
-	    }
-	}
-	ASSERT(!(BIF_P->flags & F_P2PNR_RESCHED));
-	BIF_RET(res);
+    if (c_p->common.id == pid) {
+        rp = c_p;
+        if (locks & ~ERTS_PROC_LOCK_MAIN)
+            erts_proc_lock(c_p, locks & ~ERTS_PROC_LOCK_MAIN);
+        locks |= ERTS_PROC_LOCK_MAIN;
+    }
+    else {
+        if (flags & ERTS_PI_FLAG_FORCE_SIG_SEND)
+            goto send_signal;
+        rp = erts_try_lock_sig_free_proc(pid, locks, &state);
+        if (!rp)
+            goto undefined;
+        if (rp == ERTS_PROC_LOCK_BUSY) {
+            rp = NULL;
+            goto send_signal;
+        }
+        if (state & ERTS_PSFLG_EXITING) {
+            if (locks)
+                erts_proc_unlock(rp, locks);
+            locks = 0;
+            /* wait for it to terminate properly... */
+            goto send_signal;
+        }
+        if (flags & ERTS_PI_FLAG_NEED_MSGQ_LEN) {
+            ASSERT(locks & ERTS_PROC_LOCK_MAIN);
+            erts_proc_lock(rp, ERTS_PROC_LOCK_MSGQ);
+            erts_proc_sig_fetch(rp);
+            if (c_p->sig_qs.cont) {
+                erts_proc_unlock(rp, locks|ERTS_PROC_LOCK_MSGQ);
+                locks = 0;
+                goto send_signal;
+            }
+            erts_proc_unlock(rp, ERTS_PROC_LOCK_MSGQ);
+        }
     }
 
-    if (pi_arg2ix(BIF_ARG_2) < 0)
-	BIF_ERROR(BIF_P, BADARG);
+    erts_factory_proc_init(&hfact, c_p);
 
-    info_locks = pi_locks(BIF_ARG_2); 
+    res = erts_process_info(c_p, &hfact, rp, locks, item_ix, len,
+                            flags, reserve_size, &reds);
 
-    rp = pi_lookup_proc(BIF_P, pid, &info_locks);
-    if (!rp) {
-        if (BIF_P->common.id == pid)
-            ERTS_BIF_EXITED(BIF_P);
-	BIF_RET(am_undefined);
+    erts_factory_close(&hfact);
+
+    if (reds > INT_MAX/2)
+        reds = INT_MAX/2;
+    BUMP_REDS(c_p, (int) reds);
+
+    state = erts_atomic32_read_acqb(&rp->state);
+    if (state & (ERTS_PSFLG_EXITING|ERTS_PSFLG_FREE)) {
+        if (state & ERTS_PSFLG_FREE) {
+            ASSERT(!locks);
+            goto undefined;
+        }
+        if (locks)
+            erts_proc_unlock(rp, locks);
+        locks = 0;
+        /* wait for it to terminate properly... */
+        goto send_signal;
     }
-    else if (rp == ERTS_PROC_LOCK_BUSY)
-	ERTS_BIF_YIELD2(bif_export[BIF_process_info_2], BIF_P,
-			BIF_ARG_1, BIF_ARG_2);
 
-    if (BIF_P == rp)
-        info_locks |= ERTS_PROC_LOCK_MAIN;
+    ERTS_BIF_PREP_RET(ret, res);
+
+done:
 
-    res = process_info_aux(BIF_P, rp, info_locks, pid, BIF_ARG_2,
-                           0, &reds);
+    if (c_p == rp)
+        locks &= ~ERTS_PROC_LOCK_MAIN;
 
-    BUMP_REDS(BIF_P, reds);
+    if (locks && rp)
+	erts_proc_unlock(rp, locks);
 
-    if (BIF_P == rp)
-	info_locks &= ~ERTS_PROC_LOCK_MAIN;
-    if (rp && info_locks)
-	erts_proc_unlock(rp, info_locks);
+    if (item_ix != def_arr)
+        erts_free(ERTS_ALC_T_TMP, item_ix);
 
-    ASSERT(!(BIF_P->flags & F_P2PNR_RESCHED));
-    BIF_RET(res);
+    return ret;
+
+badarg:
+    ERTS_BIF_PREP_ERROR(ret, c_p, BADARG);
+    goto done;
+
+undefined:
+    ERTS_BIF_PREP_RET(ret, am_undefined);
+    goto done;
+
+exited:
+    ERTS_BIF_PREP_EXITED(ret, c_p);
+    goto done;
+
+yield:
+    if (pi2)
+        ERTS_BIF_PREP_YIELD2(ret, bif_export[BIF_process_info_2], c_p, pid, opt);
+    else
+        ERTS_BIF_PREP_YIELD1(ret, bif_export[BIF_process_info_1], c_p, pid);
+    goto done;
+
+send_signal: {
+        Eterm ref = erts_make_ref(c_p);
+        int enqueued, need_msgq_len;
+        flags |= ERTS_PI_FLAG_REQUEST_FOR_OTHER;
+        need_msgq_len = (flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
+        /*
+         * Set receive mark so we wont have to scan the whole
+         * message queue for the result. Note caller unconditionally
+         * has to enter a receive only matching messages containing
+         * 'ref', or restore save pointer.
+         */
+        ERTS_RECV_MARK_SAVE(c_p);
+        ERTS_RECV_MARK_SET(c_p);
+        enqueued = erts_proc_sig_send_process_info_request(c_p, pid, item_ix,
+                                                           len, need_msgq_len,
+                                                           flags, reserve_size,
+                                                           ref);
+        if (!enqueued) {
+            /* Restore save pointer... */
+	    JOIN_MESSAGE(c_p);
+            goto undefined;
+        }
+        ERTS_BIF_PREP_TRAP1(ret, erts_await_result, c_p, ref);
+        goto done;
+    }
+}
+
+static void
+pi_setup_grow(int **arr, int *def_arr, Uint *sz, int ix)
+{
+    *sz = (ix+1) + ERTS_PI_DEF_ARR_SZ;
+    if (*arr != def_arr)
+        *arr = erts_realloc(ERTS_ALC_T_TMP, *arr, (*sz)*sizeof(int));
+    else {
+        int *new_arr = erts_alloc(ERTS_ALC_T_TMP, (*sz)*sizeof(int));
+        sys_memcpy((void *) new_arr, (void *) def_arr,
+                   sizeof(int)*ERTS_PI_DEF_ARR_SZ);
+        *arr = new_arr;
+    }
+}
+
+
+BIF_RETTYPE process_info_2(BIF_ALIST_2)
+{
+    return process_info_bif(BIF_P, BIF_ARG_1, BIF_ARG_2, !is_atom(BIF_ARG_2), !0);
+}
+
+BIF_RETTYPE process_info_1(BIF_ALIST_1)
+{
+    return process_info_bif(BIF_P, BIF_ARG_1, pi_1_keys_list, 0, 0);
 }
 
 Eterm
-process_info_aux(Process *BIF_P,
+process_info_aux(Process *c_p,
+                 ErtsHeapFactory *hfact,
 		 Process *rp,
 		 ErtsProcLocks rp_locks,
-		 Eterm rpid,
-		 Eterm item,
-		 int always_wrap,
-                 int *reds)
+		 int item_ix,
+		 int flags,
+                 Uint *reserve_sizep,
+                 Uint *reds)
 {
     Eterm *hp;
     Eterm res = NIL;
+    Uint reserved;
+    Uint reserve_size = *reserve_sizep;
+
+#ifdef ERTS_ENABLE_LOCK_CHECK
+    ErtsProcLocks locks = erts_proc_lc_my_proc_locks(rp);
+
+    switch (item_ix) {
+    case ERTS_PI_IX_STATUS:
+    case ERTS_PI_IX_PRIORITY:
+    case ERTS_PI_IX_SUSPENDING:
+        ERTS_LC_ASSERT((locks & ~ERTS_PROC_LOCK_MAIN) == 0);
+        break;
+    default:
+        ERTS_LC_ASSERT(locks == ERTS_PROC_LOCK_MAIN);
+        break;
+    }
+#endif
+
+    reserved = pi_ix2rsz(item_ix);
+    ERTS_PI_UNRESERVE(reserve_size, reserved);
 
     (*reds)++;
 
     ASSERT(rp);
 
     /*
-     * Q: Why this always_wrap argument?
+     * Q: Why this ERTS_PI_FLAG_ALWAYS_WRAP flag?
      *
      * A: registered_name is strange. If process has no registered name,
      *    process_info(Pid, registered_name) returns [], and
@@ -1241,41 +1352,39 @@ process_info_aux(Process *BIF_P,
      *    registered_name behaves as it should, i.e. a
      *    {registered_name, []} will appear in the resulting list.
      *
-     *    If always_wrap != 0, process_info_aux() always wrap the result
-     *    in a key two tuple. 
+     *    If ERTS_PI_FLAG_ALWAYS_WRAP is set, process_info_aux() always
+     *    wrap the result in a key two tuple. 
      */
 
-    switch (item) {
+    switch (item_ix) {
 
-    case am_registered_name:
-	if (rp->common.u.alive.reg) {
-	    hp = HAlloc(BIF_P, 3);
+    case ERTS_PI_IX_REGISTERED_NAME:
+	if (rp->common.u.alive.reg)
 	    res = rp->common.u.alive.reg->name;
-	} else {
-	    if (always_wrap) {
-		hp = HAlloc(BIF_P, 3);
+        else {
+	    if (flags & ERTS_PI_FLAG_ALWAYS_WRAP)
 		res = NIL;
-	    }
-	    else {
+	    else
 		return NIL;
-	    }
 	}
 	break;
 
-    case am_current_function:
-	res = current_function(BIF_P, rp, &hp, 0);
+    case ERTS_PI_IX_CURRENT_FUNCTION:
+	res = current_function(c_p, hfact, rp, 0,
+                               reserve_size, flags);
 	break;
 
-    case am_current_location:
-	res = current_function(BIF_P, rp, &hp, 1);
+    case ERTS_PI_IX_CURRENT_LOCATION:
+	res = current_function(c_p, hfact, rp, 1,
+                               reserve_size, flags);
 	break;
 
-    case am_current_stacktrace:
-	res = current_stacktrace(BIF_P, rp, &hp);
+    case ERTS_PI_IX_CURRENT_STACKTRACE:
+	res = current_stacktrace(hfact, rp, reserve_size);
 	break;
 
-    case am_initial_call:
-	hp = HAlloc(BIF_P, 3+4);
+    case ERTS_PI_IX_INITIAL_CALL:
+        hp = erts_produce_heap(hfact, 4, reserve_size);
 	res = TUPLE3(hp,
 		     rp->u.initial.module,
 		     rp->u.initial.function,
@@ -1283,24 +1392,37 @@ process_info_aux(Process *BIF_P,
 	hp += 4;
 	break;
 
-    case am_status:
-        res = erts_process_state2status(erts_atomic32_read_nob(&rp->state));
-        if (res == am_exiting || res == am_free)
-            return am_undefined;
-	hp = HAlloc(BIF_P, 3);
+    case ERTS_PI_IX_STATUS: {
+        erts_aint32_t state = erts_atomic32_read_nob(&rp->state);
+        res = erts_process_state2status(state);
+        if (res == am_running && (state & ERTS_PSFLG_RUNNING_SYS)) {
+            ASSERT(c_p == rp);
+            ASSERT(flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER);
+            if (!(state & (ERTS_PSFLG_SYS_TASKS
+                           | ERTS_PSFLG_ACTIVE
+                           | ERTS_PSFLG_SIG_Q
+                           | ERTS_PSFLG_SIG_IN_Q))) {
+                /*
+                 * We are servicing a process-info request from
+                 * another process. If that other process could
+                 * have inspected our state itself, we would have
+                 * been in the 'waiting' state.
+                 */
+                res = am_waiting;
+            }
+        }
 	break;
+    }
 
-    case am_messages: {
-
-	if (rp->sig_qs.len == 0 || ERTS_TRACE_FLAGS(rp) & F_SENSITIVE) {
-	    hp = HAlloc(BIF_P, 3);
-	} else {
+    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))
+            res = NIL;
+        else {
+            int info_on_self = !(flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER);
 	    ErtsMessageInfo *mip;
-	    Sint i;
+	    Sint i, len;
 	    Uint heap_need;
-#ifdef DEBUG
-	    Eterm *hp_end;
-#endif
 
 	    mip = erts_alloc(ERTS_ALC_T_TMP,
 			     rp->sig_qs.len*sizeof(ErtsMessageInfo));
@@ -1310,46 +1432,52 @@ process_info_aux(Process *BIF_P,
 	     * erts_proc_sig_prep_msgq_for_inspection() since it removes
 	     * corrupt distribution messages.
 	     */
-	    heap_need = erts_proc_sig_prep_msgq_for_inspection(BIF_P, rp,
-                                                               rp_locks, mip);
-	    heap_need += 3; /* top 2-tuple */
-	    heap_need += rp->sig_qs.len*2; /* Cons cells */
+	    heap_need = erts_proc_sig_prep_msgq_for_inspection(c_p, rp,
+                                                               rp_locks,
+                                                               info_on_self,
+                                                               mip);
+            len = rp->sig_qs.len;
 
-	    hp = HAlloc(BIF_P, heap_need); /* heap_need is exact */
-#ifdef DEBUG
-	    hp_end = hp + heap_need;
-#endif
+	    heap_need += len*2; /* Cons cells */
+
+            reserve_size += heap_need;
 
 	    /* Build list of messages... */
-	    for (i = rp->sig_qs.len - 1, res = NIL; i >= 0; i--) {
+	    for (i = len - 1, res = NIL; i >= 0; i--) {
 		Eterm msg = ERL_MESSAGE_TERM(mip[i].msgp);
 		Uint sz = mip[i].size;
 
+                ERTS_PI_UNRESERVE(reserve_size, sz+2);
+                hp = erts_produce_heap(hfact, sz+2, reserve_size);
+
 		if (sz != 0)
-		    msg = copy_struct(msg, sz, &hp, &BIF_P->off_heap);
+		    msg = copy_struct(msg, sz, &hp, hfact->off_heap);
 
 		res = CONS(hp, msg, res);
 		hp += 2;
 	    }
 
-	    ASSERT(hp_end == hp + 3);
-
-            if (rp->sig_qs.len > CONTEXT_REDS*4)
-                *reds += CONTEXT_REDS*4;
-            else
-                *reds += rp->sig_qs.len / 4;
+            *reds += (Uint) len / 4;
 
 	    erts_free(ERTS_ALC_T_TMP, mip);
 	}
 	break;
     }
 
-    case am_message_queue_len:
-	hp = HAlloc(BIF_P, 3);
-	res = make_small(rp->sig_qs.len);
+    case ERTS_PI_IX_MESSAGE_QUEUE_LEN: {
+        Sint len = rp->sig_qs.len;
+        ASSERT(flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
+        ASSERT(len >= 0);
+        if (len <= MAX_SMALL)
+            res = make_small(len);
+        else {
+            hp = erts_produce_heap(hfact, BIG_UINT_HEAP_SIZE, reserve_size);
+            res = uint_to_big((Uint) len, hp);
+        }
 	break;
+    }
 
-    case am_links: {
+    case ERTS_PI_IX_LINKS: {
 	MonitorInfoCollection mic;
 	int i;
 	Eterm item;
@@ -1358,24 +1486,24 @@ process_info_aux(Process *BIF_P,
 
 	erts_link_tree_foreach(ERTS_P_LINKS(rp), collect_one_link, (void *) &mic);
 
-	hp = HAlloc(BIF_P, 3 + mic.sz);
+        reserve_size += mic.sz;
 	res = NIL;
 	for (i = 0; i < mic.mi_i; i++) {
-	    item = STORE_NC(&hp, &MSO(BIF_P), mic.mi[i].entity.term); 
+            Eterm item_src = mic.mi[i].entity.term;
+            Uint sz = NC_HEAP_SIZE(item_src) + 2;
+            ERTS_PI_UNRESERVE(reserve_size, sz);
+            hp = erts_produce_heap(hfact, sz, reserve_size);
+	    item = STORE_NC(&hp, hfact->off_heap, item_src); 
 	    res = CONS(hp, item, res);
-	    hp += 2;
 	}
 
-        if (mic.mi_i > CONTEXT_REDS*4)
-            *reds += CONTEXT_REDS*4;
-        else
-            *reds += mic.mi_i / 4;
+        *reds += (Uint) mic.mi_i / 4;
 
 	DESTROY_MONITOR_INFOS(mic);
 	break;
     }
 
-    case am_monitors: {
+    case ERTS_PI_IX_MONITORS: {
 	MonitorInfoCollection mic;
         int i;
 
@@ -1384,7 +1512,7 @@ process_info_aux(Process *BIF_P,
                                   collect_one_origin_monitor,
                                   (void *) &mic);
 
-        hp = HAlloc(BIF_P, 3 + mic.sz);
+        reserve_size += mic.sz;
 	res = NIL;
 	for (i = 0; i < mic.mi_i; i++) {
 	    if (mic.mi[i].named) {
@@ -1399,23 +1527,30 @@ process_info_aux(Process *BIF_P,
                     || is_port(mic.mi[i].pid)
                     || is_atom(mic.mi[i].pid));
 
+                ERTS_PI_UNRESERVE(reserve_size, 3+3+2);
+                hp = erts_produce_heap(hfact, 3+3+2, reserve_size);
+
 		t1 = TUPLE2(hp, mic.mi[i].entity.term, mic.mi[i].node);
 		hp += 3;
                 t2 = TUPLE2(hp, m_type, t1);
 		hp += 3;
 		res = CONS(hp, t2, res);
-                hp += 2;
 	    }
 	    else {
                 /* Build {process|port|time_offset, Pid|clock_service} and cons it. */
 		Eterm t;
 		Eterm pid;
                 Eterm m_type;
+                Eterm pid_src = mic.mi[i].entity.term;
+                Uint sz = is_atom(pid_src) ? 0 : NC_HEAP_SIZE(pid_src);
+                sz += 3 + 2;
 
-                if (is_atom(mic.mi[i].entity.term))
-                    pid = mic.mi[i].entity.term;
-                else
-                    pid = STORE_NC(&hp, &MSO(BIF_P), mic.mi[i].entity.term);
+                ERTS_PI_UNRESERVE(reserve_size, sz);
+                hp = erts_produce_heap(hfact, sz, reserve_size);
+
+                pid = (is_atom(pid_src)
+                       ? pid_src
+                       : STORE_NC(&hp, hfact->off_heap, pid_src));
 
                 switch (mic.mi[i].type) {
                 case ERTS_MON_TYPE_PORT:
@@ -1435,20 +1570,16 @@ process_info_aux(Process *BIF_P,
                 t = TUPLE2(hp, m_type, pid);
 		hp += 3;
 		res = CONS(hp, t, res);
-                hp += 2;
 	    }
 	}
 
-        if (mic.mi_i > CONTEXT_REDS*4)
-            *reds += CONTEXT_REDS*4;
-        else
-            *reds += mic.mi_i / 4;
+        *reds += (Uint) mic.mi_i / 4;
 
         DESTROY_MONITOR_INFOS(mic);
 	break;
     }
 
-    case am_monitored_by: {
+    case ERTS_PI_IX_MONITORED_BY: {
 	MonitorInfoCollection mic;
 	int i;
 	Eterm item;
@@ -1461,59 +1592,71 @@ process_info_aux(Process *BIF_P,
                                   collect_one_target_monitor,
                                   (void *) &mic);
 
-	hp = HAlloc(BIF_P, 3 + mic.sz);
+        reserve_size += mic.sz;
 
 	res = NIL;
 	for (i = 0; i < mic.mi_i; ++i) {
+            Uint sz = 2;
+
+            if (mic.mi[i].type == ERTS_MON_TYPE_RESOURCE)
+                sz += erts_resource_ref_size(mic.mi[i].entity.resource);
+            else
+                sz += NC_HEAP_SIZE(mic.mi[i].entity.term);
+
+            ERTS_PI_UNRESERVE(reserve_size, sz);
+            hp = erts_produce_heap(hfact, sz, reserve_size);
+
             if (mic.mi[i].type == ERTS_MON_TYPE_RESOURCE)
                 item = erts_bld_resource_ref(&hp,
-                                             &MSO(BIF_P),
+                                             hfact->off_heap,
                                              mic.mi[i].entity.resource);
             else
                 item = STORE_NC(&hp,
-                                &MSO(BIF_P),
+                                hfact->off_heap,
                                 mic.mi[i].entity.term);
 	    res = CONS(hp, item, res);
-	    hp += 2;
 	}
 
-        if (mic.mi_i > CONTEXT_REDS*4)
-            *reds += CONTEXT_REDS*4;
-        else
-            *reds += mic.mi_i / 4;
+        *reds += (Uint) mic.mi_i / 4;
 
 	DESTROY_MONITOR_INFOS(mic);
 	break;
     }
 
-    case am_suspending: {
+    case ERTS_PI_IX_SUSPENDING: {
 	ErtsSuspendMonitorInfoCollection smic;
 	int i;
 	Eterm item;
-#ifdef DEBUG
-	Eterm *hp_end;
-#endif
+
+        erts_proc_lock(rp, ERTS_PROC_LOCK_STATUS);
 
 	ERTS_INIT_SUSPEND_MONITOR_INFOS(smic,
-					BIF_P,
-					(BIF_P == rp
+					c_p,
+					(c_p == rp
 					 ? ERTS_PROC_LOCK_MAIN
 					 : 0) | ERTS_PROC_LOCK_STATUS);
 
 	erts_monitor_tree_foreach(rp->suspend_monitors,
                                   &collect_one_suspend_monitor,
                                   &smic);
-	hp = HAlloc(BIF_P, 3 + smic.sz);
-#ifdef DEBUG
-	hp_end = hp + smic.sz;
-#endif
-	
+
+        reserve_size += smic.sz;
+
 	res = NIL;
 	for (i = 0; i < smic.smi_i; i++) {
 	    Sint a = (Sint) smic.smi[i]->active;  /* quiet compiler warnings */
 	    Sint p = (Sint) smic.smi[i]->pending; /* on 64-bit machines...   */
 	    Eterm active;
 	    Eterm pending;
+            Uint sz = 4 + 2;
+            if (!IS_SSMALL(a))
+		sz += BIG_UINT_HEAP_SIZE;
+            if (!IS_SSMALL(p))
+		sz += BIG_UINT_HEAP_SIZE;
+
+            ERTS_PI_UNRESERVE(reserve_size, sz);
+            hp = erts_produce_heap(hfact, sz, reserve_size);
+
 	    if (IS_SSMALL(a))
 		active = make_small(a);
 	    else {
@@ -1529,95 +1672,83 @@ process_info_aux(Process *BIF_P,
 	    item = TUPLE3(hp, smic.smi[i]->mon.other.item, active, pending);
 	    hp += 4;
 	    res = CONS(hp, item, res);
-	    hp += 2;
 	}
 
-        if (smic.smi_i > CONTEXT_REDS*4)
-            *reds += CONTEXT_REDS*4;
-        else
-            *reds += smic.smi_i / 4;
+        erts_proc_unlock(rp, ERTS_PROC_LOCK_STATUS);
+
+        *reds += (Uint) smic.smi_i / 4;
 
 	ERTS_DESTROY_SUSPEND_MONITOR_INFOS(smic);
-	ASSERT(hp == hp_end);
 
 	break;
     }
 
-    case am_dictionary:
+    case ERTS_PI_IX_DICTIONARY:
 	if (!rp->dictionary || (ERTS_TRACE_FLAGS(rp) & F_SENSITIVE)) {
 	    res = NIL;
 	} else {
             Uint num = rp->dictionary->numElements;
-	    res = erts_dictionary_copy(BIF_P, rp->dictionary);
-            if (num > CONTEXT_REDS*4)
-                *reds += CONTEXT_REDS*4;
-            else
-                *reds += (int) num / 4;
+	    res = erts_dictionary_copy(hfact, rp->dictionary, reserve_size);
+            *reds += (Uint) num / 4;
 	}
-	hp = HAlloc(BIF_P, 3);
+
 	break;
 
-    case am_trap_exit: {
-	hp = HAlloc(BIF_P, 3);
-        if (rp->flags & F_TRAP_EXIT)
-	    res = am_true;
-	else
-	    res = am_false;
+    case ERTS_PI_IX_TRAP_EXIT:
+        res = (rp->flags & F_TRAP_EXIT) ? am_true : am_false;
 	break;
-    }
 
-    case am_error_handler:
-	hp = HAlloc(BIF_P, 3);
-	res = erts_proc_get_error_handler(BIF_P);
+    case ERTS_PI_IX_ERROR_HANDLER:
+	res = erts_proc_get_error_handler(rp);
 	break;
 
-    case am_heap_size: {
-	Uint hsz = 3;
+    case ERTS_PI_IX_HEAP_SIZE: {
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, HEAP_SIZE(rp));
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, HEAP_SIZE(rp));
 	break;
     }
 
-    case am_fullsweep_after: {
-	Uint hsz = 3;
+    case ERTS_PI_IX_FULLSWEEP_AFTER: {
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, MAX_GEN_GCS(rp));
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, MAX_GEN_GCS(rp));
 	break;
     }
 
-    case am_min_heap_size: {
-	Uint hsz = 3;
+    case ERTS_PI_IX_MIN_HEAP_SIZE: {
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, MIN_HEAP_SIZE(rp));
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, MIN_HEAP_SIZE(rp));
 	break;
     }
 
-    case am_min_bin_vheap_size: {
-	Uint hsz = 3;
+    case ERTS_PI_IX_MIN_BIN_VHEAP_SIZE: {
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, MIN_VHEAP_SIZE(rp));
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, MIN_VHEAP_SIZE(rp));
 	break;
     }
 
-    case am_max_heap_size: {
-	Uint hsz = 3;
+    case ERTS_PI_IX_MAX_HEAP_SIZE: {
+	Uint hsz = 0;
 	(void) erts_max_heap_size_map(MAX_HEAP_SIZE_GET(rp),
                                       MAX_HEAP_SIZE_FLAGS_GET(rp),
                                       NULL, &hsz);
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_max_heap_size_map(MAX_HEAP_SIZE_GET(rp),
                                      MAX_HEAP_SIZE_FLAGS_GET(rp),
                                      &hp, NULL);
 	break;
     }
 
-    case am_total_heap_size: {
+    case ERTS_PI_IX_TOTAL_HEAP_SIZE: {
 	Uint total_heap_size;
-	Uint hsz = 3;
+	Uint hsz = 0;
 
 	total_heap_size = rp->heap_sz;
 	if (rp->old_hend && rp->old_heap)
@@ -1626,58 +1757,52 @@ process_info_aux(Process *BIF_P,
 	total_heap_size += rp->mbuf_sz;
 
         if (rp->flags & F_ON_HEAP_MSGQ) {
-            ERTS_FOREACH_SIG_PRIVQS(
-                rp, mp,
-                {
-                    if (ERTS_SIG_IS_MSG(mp) && mp->data.attached)
-                        total_heap_size += erts_msg_attached_data_size(mp);
-                });
-
-            if (rp->sig_qs.len > CONTEXT_REDS*4)
-                *reds += CONTEXT_REDS*4;
-            else
-                *reds += rp->sig_qs.len / 4;
+            ErtsMessage *mp;
+            ASSERT(flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
+            for (mp = rp->sig_qs.first; mp; mp = mp->next) {
+                ASSERT(ERTS_SIG_IS_MSG(mp));
+                if (mp->data.attached)
+                    total_heap_size += erts_msg_attached_data_size(mp);
+            }
+            *reds += (Uint) rp->sig_qs.len / 4;
         }
 
 	(void) erts_bld_uint(NULL, &hsz, total_heap_size);
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, total_heap_size);
 	break;
     }
 
-    case am_stack_size: {
+    case ERTS_PI_IX_STACK_SIZE: {
 	Uint stack_size = STACK_START(rp) - rp->stop;
-	Uint hsz = 3;
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, stack_size);
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, stack_size);
 	break;
     }
 
-    case am_memory: { /* Memory consumed in bytes */
-	Uint hsz = 3;
+    case ERTS_PI_IX_MEMORY: { /* Memory consumed in bytes */
+	Uint hsz = 0;
 	Uint size = erts_process_memory(rp, 0);
 	(void) erts_bld_uint(NULL, &hsz, size);
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, size);
 
-        if (rp->sig_qs.len > CONTEXT_REDS*4)
-            *reds += CONTEXT_REDS*4;
-        else
-            *reds += rp->sig_qs.len / 4;
+        ASSERT(flags & ERTS_PI_FLAG_NEED_MSGQ_LEN);
+        *reds += (Uint) rp->sig_qs.len / 4;
 
 	break;
     }
 
-    case am_garbage_collection: {
+    case ERTS_PI_IX_GARBAGE_COLLECTION: {
         DECL_AM(minor_gcs);
         Eterm t;
         Uint map_sz = 0;
 
         erts_max_heap_size_map(MAX_HEAP_SIZE_GET(rp), MAX_HEAP_SIZE_FLAGS_GET(rp), NULL, &map_sz);
 
-	hp = HAlloc(BIF_P, 3+2 + 3+2 + 3+2 + 3+2 + 3+2 + map_sz + 3);
-        /* last "3" is for outside tuple */
+        hp = erts_produce_heap(hfact, 3+2 + 3+2 + 3+2 + 3+2 + 3+2 + map_sz, reserve_size);
 
 	t = TUPLE2(hp, AM_minor_gcs, make_small(GEN_GCS(rp))); hp += 3;
 	res = CONS(hp, t, NIL); hp += 2;
@@ -1696,93 +1821,76 @@ process_info_aux(Process *BIF_P,
 	break;
     }
 
-    case am_garbage_collection_info: {
+    case ERTS_PI_IX_GARBAGE_COLLECTION_INFO: {
         Uint sz = 0, actual_sz = 0;
 
-        if (rp == BIF_P) {
-            sz += ERTS_PROCESS_GC_INFO_MAX_SIZE;
-        } else {
-            erts_process_gc_info(rp, &sz, NULL, 0, 0);
-            sz += 3;
-        }
+        erts_process_gc_info(rp, &sz, NULL, 0, 0);
 
-        hp = HAlloc(BIF_P, sz);
+        hp = erts_produce_heap(hfact, sz, reserve_size);
         res = erts_process_gc_info(rp, &actual_sz, &hp, 0, 0);
 
-        /* We may have some extra space, fill with 0 tuples */
-        if (actual_sz <= sz - 3) {
-            for (; actual_sz < sz - 3; hp++, actual_sz++)
-                hp[0] = make_arityval(0);
-        } else {
-            for (; actual_sz < sz; hp++, actual_sz++)
-                hp[0] = make_arityval(0);
-            hp = HAlloc(BIF_P, 3);
-        }
-
         break;
     }
 
-    case am_group_leader: {
+    case ERTS_PI_IX_GROUP_LEADER: {
 	int sz = NC_HEAP_SIZE(rp->group_leader);
-	hp = HAlloc(BIF_P, 3 + sz);
-	res = STORE_NC(&hp, &MSO(BIF_P), rp->group_leader);
+        hp = erts_produce_heap(hfact, sz, reserve_size);
+	res = STORE_NC(&hp, hfact->off_heap, rp->group_leader);
 	break;
     }
 
-    case am_reductions: {
-	Uint reds = rp->reds + erts_current_reductions(BIF_P, rp);
-	Uint hsz = 3;
+    case ERTS_PI_IX_REDUCTIONS: {
+	Uint reds = rp->reds + erts_current_reductions(c_p, rp);
+	Uint hsz = 0;
 	(void) erts_bld_uint(NULL, &hsz, reds);
-	hp = HAlloc(BIF_P, hsz);
+        hp = erts_produce_heap(hfact, hsz, reserve_size);
 	res = erts_bld_uint(&hp, NULL, reds);
 	break;
     }
 
-    case am_priority: {
+    case ERTS_PI_IX_PRIORITY: {
         erts_aint32_t state = erts_atomic32_read_nob(&rp->state);
         if (ERTS_PSFLG_EXITING & state)
             return am_undefined;
-	hp = HAlloc(BIF_P, 3);
 	res = erts_get_process_priority(state);
 	break;
     }
 
-    case am_trace:
-	hp = HAlloc(BIF_P, 3);
+    case ERTS_PI_IX_TRACE:
 	res = make_small(ERTS_TRACE_FLAGS(rp) & TRACEE_FLAGS);
 	break;
 
-    case am_binary: {
-	Uint sz = 3;
+    case ERTS_PI_IX_BINARY: {
+	Uint sz = 0;
 	(void) bld_bin_list(NULL, &sz, &MSO(rp));
-	hp = HAlloc(BIF_P, sz);
+        hp = erts_produce_heap(hfact, sz, reserve_size);
 	res = bld_bin_list(&hp, NULL, &MSO(rp));
 	break;
     }
 
-    case am_sequential_trace_token:
-	res = copy_object(rp->seq_trace_token, BIF_P);
-	hp = HAlloc(BIF_P, 3);
+    case ERTS_PI_IX_SEQUENTIAL_TRACE_TOKEN: {
+        Uint sz = size_object(rp->seq_trace_token);
+        hp = erts_produce_heap(hfact, sz, reserve_size);
+        res = copy_struct(rp->seq_trace_token, sz, &hp, hfact->off_heap);
 	break;
+    }
 
-    case am_catchlevel:
-	hp = HAlloc(BIF_P, 3);
-	res = make_small(catchlevel(BIF_P));
+    case ERTS_PI_IX_CATCHLEVEL:
+	res = make_small(catchlevel(rp));
 	break;
 
-    case am_backtrace: {
+    case ERTS_PI_IX_BACKTRACE: {
 	erts_dsprintf_buf_t *dsbufp = erts_create_tmp_dsbuf(0);
 	erts_stack_dump(ERTS_PRINT_DSBUF, (void *) dsbufp, rp);
-	res = new_binary(BIF_P, (byte *) dsbufp->str, dsbufp->str_len);
+	res = erts_heap_factory_new_binary(hfact, (byte *) dsbufp->str,
+                                           dsbufp->str_len, reserve_size);
 	erts_destroy_tmp_dsbuf(dsbufp);
-	hp = HAlloc(BIF_P, 3);
 	break;
     }
 
-    case am_last_calls: {
+    case ERTS_PI_IX_LAST_CALLS: {
 	struct saved_calls *scb = ERTS_PROC_GET_SAVED_CALLS_BUF(rp);
 	if (!scb) {
-	    hp = HAlloc(BIF_P, 3);
 	    res = am_false;
 	} else {
 	    /*
@@ -1790,23 +1898,34 @@ process_info_aux(Process *BIF_P,
 	     * Might be less than that, if there are sends, receives or timeouts,
 	     * so we must do a HRelease() to avoid creating holes.
 	     */
-	    Uint needed = scb->n*(2+4) + 3;
-	    Eterm* limit;
+	    Sint needed = scb->n*(2+4);
 	    Eterm term, list;
 	    int i, j;
+            Export *exp;
+
+            reserve_size += needed;
 
-	    hp = HAlloc(BIF_P, needed);
-	    limit = hp + needed;
 	    list = NIL;
 	    for (i = 0; i < scb->n; i++) {
+                Uint sz;
 		j = scb->cur - i - 1;
 		if (j < 0)
 		    j += scb->len;
-		if (scb->ct[j] == &exp_send)
+
+                sz = 2;
+                exp = scb->ct[j];
+                if (exp != &exp_send && exp != &exp_receive && exp != &exp_timeout)
+                    sz += 4;
+
+                needed -= sz;
+                ERTS_PI_UNRESERVE(reserve_size, sz);
+                hp = erts_produce_heap(hfact, sz, reserve_size);
+
+		if (exp == &exp_send)
 		    term = am_send;
-		else if (scb->ct[j] == &exp_receive)
+		else if (exp == &exp_receive)
 		    term = am_receive;
-		else if (scb->ct[j] == &exp_timeout)
+		else if (exp == &exp_timeout)
 		    term = am_timeout;
 		else {
 		    term = TUPLE3(hp,
@@ -1816,18 +1935,18 @@ process_info_aux(Process *BIF_P,
 		    hp += 4;
 		}
 		list = CONS(hp, term, list);
-		hp += 2;
 	    }
+
+            ASSERT(needed >= 0);
+            if (needed > 0)
+                reserve_size -= needed;
+
 	    res = list;
-	    res = TUPLE2(hp, item, res);
-	    hp += 3;
-	    HRelease(BIF_P,limit,hp);
-	    return res;
 	}
 	break;
     }
 
-    case am_message_queue_data:
+    case ERTS_PI_IX_MESSAGE_QUEUE_DATA:
 	switch (rp->flags & (F_OFF_HEAP_MSGQ|F_ON_HEAP_MSGQ)) {
 	case F_OFF_HEAP_MSGQ:
 	    res = am_off_heap;
@@ -1840,16 +1959,15 @@ process_info_aux(Process *BIF_P,
 	    ERTS_INTERNAL_ERROR("Inconsistent message queue management state");
 	    break;
 	}
-	hp = HAlloc(BIF_P, 3);
 	break;
 
-    case am_magic_ref: {
-	Uint sz = 3;
+    case ERTS_PI_IX_MAGIC_REF: {
+	Uint sz = 0;
 	(void) bld_magic_ref_bin_list(NULL, &sz, &MSO(rp));
-	hp = HAlloc(BIF_P, sz);
+        hp = erts_produce_heap(hfact, sz, 0);
 	res = bld_magic_ref_bin_list(&hp, NULL, &MSO(rp));
 
-        *reds += 10;
+        *reds += (Uint) 10;
 	break;
     }
 
@@ -1858,12 +1976,17 @@ process_info_aux(Process *BIF_P,
 
     }
 
-    return TUPLE2(hp, item, res);
+    ERTS_PI_UNRESERVE(reserve_size, 3);
+    *reserve_sizep = reserve_size;
+    hp = erts_produce_heap(hfact, 3, reserve_size);
+
+    return TUPLE2(hp, pi_ix2arg(item_ix), res);
 }
 #undef MI_INC
 
 static Eterm
-current_function(Process* BIF_P, Process* rp, Eterm** hpp, int full_info)
+current_function(Process *c_p, ErtsHeapFactory *hfact, Process* rp,
+                 int full_info, Uint reserve_size, int flags)
 {
     Eterm* hp;
     Eterm res;
@@ -1880,7 +2003,7 @@ current_function(Process* BIF_P, Process* rp, Eterm** hpp, int full_info)
 	}
     }
 
-    if (BIF_P == rp) {
+    if (c_p == rp && !(flags & ERTS_PI_FLAG_REQUEST_FOR_OTHER)) {
 	FunctionInfo fi2;
 
 	/*
@@ -1900,24 +2023,22 @@ current_function(Process* BIF_P, Process* rp, Eterm** hpp, int full_info)
      * Return the result.
      */
     if (rp->current == NULL) {
-	hp = HAlloc(BIF_P, 3);
 	res = am_undefined;
     } else if (full_info) {
-	hp = HAlloc(BIF_P, 3+fi.needed);
-	hp = erts_build_mfa_item(&fi, hp, am_true, &res);
+        hp = erts_produce_heap(hfact, fi.needed, reserve_size);
+	erts_build_mfa_item(&fi, hp, am_true, &res);
     } else {
-	hp = HAlloc(BIF_P, 3+4);
+        hp = erts_produce_heap(hfact, 4, reserve_size);
 	res = TUPLE3(hp, rp->current->module,
 		     rp->current->function,
                      make_small(rp->current->arity));
-	hp += 4;
     }
-    *hpp = hp;
     return res;
 }
 
 static Eterm
-current_stacktrace(Process* p, Process* rp, Eterm** hpp)
+current_stacktrace(ErtsHeapFactory *hfact, Process* rp,
+                   Uint reserve_size)
 {
     Uint sz;
     struct StackTrace* s;
@@ -1926,7 +2047,7 @@ current_stacktrace(Process* p, Process* rp, Eterm** hpp)
     FunctionInfo* stkp;
     Uint heap_size;
     int i;
-    Eterm* hp = *hpp;
+    Eterm* hp;
     Eterm mfa;
     Eterm res = NIL;
 
@@ -1956,17 +2077,23 @@ current_stacktrace(Process* p, Process* rp, Eterm** hpp)
 	}
     }
 
-    hp = HAlloc(p, heap_size);
+    reserve_size += heap_size;
+
+    /*
+     * We intentionally produce heap in small chunks
+     * (for more info see process_info_aux()).
+     */
     while (stkp > stk) {
 	stkp--;
+        sz = stkp->needed + 2;
+        ERTS_PI_UNRESERVE(reserve_size, sz);
+        hp = erts_produce_heap(hfact, sz, reserve_size);
 	hp = erts_build_mfa_item(stkp, hp, am_true, &mfa);
 	res = CONS(hp, mfa, res);
-	hp += 2;
     }
 
     erts_free(ERTS_ALC_T_TMP, stk);
     erts_free(ERTS_ALC_T_TMP, s);
-    *hpp = hp;
     return res;
 }
 
@@ -3838,7 +3965,7 @@ BIF_RETTYPE erts_debug_get_internal_state_1(BIF_ALIST_1)
 	    Eterm res = NIL;
 	    Uint *hp = HAlloc(BIF_P, 2*ERTS_PI_ARGS);
 	    for (i = ERTS_PI_ARGS-1; i >= 0; i--) {
-		res = CONS(hp, pi_args[i], res);
+		res = CONS(hp, pi_args[i].name, res);
 		hp += 2;
 	    }
 	    BIF_RET(res);
diff --git a/erts/emulator/beam/erl_gc.c b/erts/emulator/beam/erl_gc.c
index 5da8e3eda5..ea87cd7f50 100644
--- a/erts/emulator/beam/erl_gc.c
+++ b/erts/emulator/beam/erl_gc.c
@@ -61,7 +61,7 @@
 #  define ERTS_GC_ASSERT(B) ((void) 1)
 #endif
 
-#if defined(DEBUG) && 0
+#if defined(DEBUG) && 1
 #  define HARDDEBUG 1
 #endif
 
@@ -222,6 +222,24 @@ ERTS_SCHED_PREF_QUICK_ALLOC_IMPL(gcireq,
                                  ErtsGCInfoReq,
                                  5,
                                  ERTS_ALC_T_GC_INFO_REQ)
+
+static ERTS_INLINE void
+ensure_sigq_roots_available(Process *p)
+{
+    ERTS_LC_ASSERT(ERTS_PROC_LOCK_MAIN == erts_proc_lc_my_proc_locks(p));
+    switch (p->flags & (F_OFF_HEAP_MSGQ|F_OFF_HEAP_MSGQ_CHNG)) {
+    case F_OFF_HEAP_MSGQ_CHNG:
+    case 0:
+        erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
+        erts_proc_sig_fetch(p);
+        erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+        break;
+    default:
+        break;
+    }
+}
+
+
 /*
  * Initialize GC global data.
  */
@@ -425,6 +443,8 @@ erts_gc_after_bif_call_lhf(Process* p, ErlHeapFragment *live_hf_end,
 	live_hf_end = ERTS_INVALID_HFRAG_PTR;
     }
 
+    ensure_sigq_roots_available(p);
+
     if (is_non_value(result)) {
 	if (p->freason == TRAP) {
 #ifdef HIPE
@@ -642,7 +662,7 @@ check_for_possibly_long_gc(Process *p, Uint ygen_usage)
     sz = ygen_usage;
     sz += p->hend - p->stop;
     if (p->flags & F_ON_HEAP_MSGQ)
-        sz += p->sig_qs.len;
+        sz += erts_proc_sig_privqs_len(p);
     if (major)
 	sz += p->old_htop - p->old_heap;
 
@@ -868,8 +888,11 @@ do_major_collection:
 int
 erts_garbage_collect_nobump(Process* p, int need, Eterm* objv, int nobj, int fcalls)
 {
-    int reds = garbage_collect(p, ERTS_INVALID_HFRAG_PTR, need, objv, nobj, fcalls, 0);
-    int reds_left = ERTS_REDS_LEFT(p, fcalls);
+    int reds; 
+    int reds_left;
+    ensure_sigq_roots_available(p);
+    reds = garbage_collect(p, ERTS_INVALID_HFRAG_PTR, need, objv, nobj, fcalls, 0);
+    reds_left = ERTS_REDS_LEFT(p, fcalls);
     if (reds > reds_left)
 	reds = reds_left;
     ASSERT(CONTEXT_REDS - (reds_left - reds) >= erts_proc_sched_data(p)->virtual_reds);
@@ -879,7 +902,9 @@ erts_garbage_collect_nobump(Process* p, int need, Eterm* objv, int nobj, int fca
 void
 erts_garbage_collect(Process* p, int need, Eterm* objv, int nobj)
 {
-    int reds = garbage_collect(p, ERTS_INVALID_HFRAG_PTR, need, objv, nobj, p->fcalls, 0);
+    int reds;
+    ensure_sigq_roots_available(p);
+    reds = garbage_collect(p, ERTS_INVALID_HFRAG_PTR, need, objv, nobj, p->fcalls, 0);
     BUMP_REDS(p, reds);
     ASSERT(CONTEXT_REDS - ERTS_BIF_REDS_LEFT(p)
 	   >= erts_proc_sched_data(p)->virtual_reds);
@@ -1105,6 +1130,8 @@ erts_garbage_collect_literals(Process* p, Eterm* literals,
      * First an ordinary major collection...
      */
 
+    ensure_sigq_roots_available(p);
+
     p->flags |= F_NEED_FULLSWEEP;
 
     if (ERTS_SCHEDULER_IS_DIRTY(erts_proc_sched_data(p)))
@@ -2541,14 +2568,17 @@ setup_rootset(Process *p, Eterm *objv, int nobj, Rootset *rootset)
 	break;
     case F_OFF_HEAP_MSGQ_CHNG:
     case 0: {
+        Sint len;
 	/*
 	 * We do not have off heap message queue enabled, i.e. we
-	 * need to add message queue to rootset...
+	 * need to add signal queues to rootset...
 	 */
 
+        len = erts_proc_sig_privqs_len(p);
+
 	/* Ensure large enough rootset... */
-	if (n + p->sig_qs.len > rootset->size) {
-	    Uint new_size = n + p->sig_qs.len;
+	if (n + len > rootset->size) {
+	    Uint new_size = n + len;
 	    ERTS_GC_ASSERT(roots == rootset->def);
 	    roots = erts_alloc(ERTS_ALC_T_ROOTSET,
 			       new_size*sizeof(Roots));
@@ -3448,7 +3478,7 @@ erts_max_heap_size_map(Sint max_heap_size, Uint max_heap_flags,
                        Eterm **hpp, Uint *sz)
 {
     if (!hpp) {
-        *sz += (2*3 + 1 + MAP_HEADER_FLATMAP_SZ);
+        *sz += ERTS_MAX_HEAP_SIZE_MAP_SZ;
         return THE_NON_VALUE;
     } else {
         Eterm *hp = *hpp;
diff --git a/erts/emulator/beam/erl_gc.h b/erts/emulator/beam/erl_gc.h
index 63d03cdf8b..b9b1ed728c 100644
--- a/erts/emulator/beam/erl_gc.h
+++ b/erts/emulator/beam/erl_gc.h
@@ -154,6 +154,8 @@ typedef struct {
   Uint64 garbage_cols;
 } ErtsGCInfo;
 
+#define ERTS_MAX_HEAP_SIZE_MAP_SZ (2*3 + 1 + MAP_HEADER_FLATMAP_SZ)
+
 #define ERTS_PROCESS_GC_INFO_MAX_TERMS (11)  /* number of elements in process_gc_info*/
 #define ERTS_PROCESS_GC_INFO_MAX_SIZE                                   \
     (ERTS_PROCESS_GC_INFO_MAX_TERMS * (2/*cons*/ + 3/*2-tuple*/ + BIG_UINT_HEAP_SIZE))
diff --git a/erts/emulator/beam/erl_message.c b/erts/emulator/beam/erl_message.c
index 93fd9859a5..34bd11d87c 100644
--- a/erts/emulator/beam/erl_message.c
+++ b/erts/emulator/beam/erl_message.c
@@ -322,7 +322,6 @@ queue_messages(Process* receiver,
                ErtsMessage** last,
                Uint len)
 {
-    Sint res;
     int locked_msgq = 0;
     erts_aint32_t state;
 
@@ -370,31 +369,14 @@ queue_messages(Process* receiver,
 	return 0;
     }
 
-    res = receiver->sig_qs.len;
-    if (receiver_locks & ERTS_PROC_LOCK_MAIN) {
-	/*
-	 * We move 'in queue' to 'private queue' and place
-	 * message at the end of 'private queue' in order
-	 * to ensure that the 'in queue' doesn't contain
-	 * references into the heap. By ensuring this,
-	 * we don't need to include the 'in queue' in
-	 * the root set when garbage collecting.
-	 */
-	res += receiver->sig_inq.len;
-        erts_proc_sig_fetch(receiver);
-        LINK_MESSAGE_PRIVQ(receiver, first, last, len);
-    }
-    else
-    {
-	LINK_MESSAGE(receiver, first, last, len);
-    }
+    LINK_MESSAGE(receiver, first, last, len);
 
     if (locked_msgq) {
 	erts_proc_unlock(receiver, ERTS_PROC_LOCK_MSGQ);
     }
 
     erts_proc_notify_new_message(receiver, receiver_locks);
-    return res;
+    return 0;
 }
 
 static Sint
@@ -846,7 +828,7 @@ erts_move_messages_off_heap(Process *c_p)
      * it...
      */
 
-    reds += c_p->sig_qs.len / 10;
+    reds += erts_proc_sig_privqs_len(c_p) / 10;
 
     ASSERT(erts_atomic32_read_nob(&c_p->state)
 	   & ERTS_PSFLG_OFF_HEAP_MSGQ);
@@ -1337,32 +1319,18 @@ void erts_factory_dummy_init(ErtsHeapFactory* factory)
     factory->mode = FACTORY_CLOSED;
 }
 
-static void reserve_heap(ErtsHeapFactory*, Uint need, Uint xtra);
-
-Eterm* erts_produce_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
-{
-    Eterm* res;
-
-    ASSERT((unsigned int)factory->mode > (unsigned int)FACTORY_CLOSED);
-    if (factory->hp + need > factory->hp_end) {
-	reserve_heap(factory, need, xtra);
-    }
-    res = factory->hp;
-    factory->hp += need;
-    return res;
-}
-
 Eterm* erts_reserve_heap(ErtsHeapFactory* factory, Uint need)
 {
     ASSERT((unsigned int)factory->mode > (unsigned int)FACTORY_CLOSED);
     if (factory->hp + need > factory->hp_end) {
-	reserve_heap(factory, need, 200);
+	erts_reserve_heap__(factory, need, 200);
     }
     return factory->hp;
 }
 
-static void reserve_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
+void erts_reserve_heap__(ErtsHeapFactory* factory, Uint need, Uint xtra)
 {
+    /* internal... */
     ErlHeapFragment* bp;
 
     switch (factory->mode) {
@@ -1372,7 +1340,9 @@ static void reserve_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
 	factory->hp_end = factory->hp + need;
 	return;
 
-    case FACTORY_MESSAGE:
+    case FACTORY_MESSAGE: {
+        int replace_oh;
+        int replace_msg_hfrag;
 	if (!factory->heap_frags) {
 	    ASSERT(factory->message->data.attached == ERTS_MSG_COMBINED_HFRAG);
 	    bp = &factory->message->hfrag;
@@ -1384,25 +1354,45 @@ static void reserve_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
 	    bp = factory->heap_frags;
 	}
 
+        replace_oh = 0;
+        replace_msg_hfrag = 0;
+
         if (bp) {
-	    ASSERT(factory->hp > bp->mem);
+	    ASSERT(factory->hp >= bp->mem);
 	    ASSERT(factory->hp <= factory->hp_end);
 	    ASSERT(factory->hp_end == bp->mem + bp->alloc_size);
 
 	    bp->used_size = factory->hp - bp->mem;
+            if (!bp->used_size && factory->heap_frags) {
+                factory->heap_frags = bp->next;
+                bp->next = NULL;
+                ASSERT(!bp->off_heap.first);
+                if (factory->off_heap == &bp->off_heap)
+                    replace_oh = !0;
+                if (factory->message && factory->message->data.heap_frag == bp)
+                    replace_msg_hfrag = !0;
+                free_message_buffer(bp);
+            }
         }
 	bp = (ErlHeapFragment*) ERTS_HEAP_ALLOC(factory->alloc_type,
 						ERTS_HEAP_FRAG_SIZE(need+xtra));
 	bp->next = factory->heap_frags;
 	factory->heap_frags = bp;
 	bp->alloc_size = need + xtra;
-	bp->used_size = need;
+	bp->used_size = need + xtra;
 	bp->off_heap.first = NULL;
 	bp->off_heap.overhead = 0;
-
+        if (replace_oh) {
+            factory->off_heap = &bp->off_heap;
+            factory->off_heap_saved.first = factory->off_heap->first;
+            factory->off_heap_saved.overhead = factory->off_heap->overhead;
+        }
+        if (replace_msg_hfrag)
+            factory->message->data.heap_frag = bp;
 	factory->hp     = bp->mem;
 	factory->hp_end = bp->mem + bp->alloc_size;
 	return;
+    }
 
     case FACTORY_STATIC:
     case FACTORY_CLOSED:
@@ -1485,9 +1475,11 @@ void erts_factory_trim_and_close(ErtsHeapFactory* factory,
         if (bp->next == NULL) {
             Uint used_sz = factory->hp - bp->mem;
             ASSERT(used_sz <= bp->alloc_size);
-	    if (used_sz > 0)
-		bp = erts_resize_message_buffer(bp, used_sz,
-						brefs, brefs_size);
+	    if (used_sz > 0) {
+                if (used_sz != bp->alloc_size)
+                    bp = erts_resize_message_buffer(bp, used_sz,
+                                                    brefs, brefs_size);
+            }
 	    else {
 		free_message_buffer(bp);
 		bp = NULL;
diff --git a/erts/emulator/beam/erl_message.h b/erts/emulator/beam/erl_message.h
index f56a252aef..ee87297ba4 100644
--- a/erts/emulator/beam/erl_message.h
+++ b/erts/emulator/beam/erl_message.h
@@ -89,12 +89,33 @@ void erts_factory_static_init(ErtsHeapFactory*, Eterm* hp, Uint size, ErlOffHeap
 void erts_factory_tmp_init(ErtsHeapFactory*, Eterm* hp, Uint size, Uint32 atype);
 void erts_factory_dummy_init(ErtsHeapFactory*);
 
-Eterm* erts_produce_heap(ErtsHeapFactory*, Uint need, Uint xtra);
+ERTS_GLB_INLINE Eterm* erts_produce_heap(ErtsHeapFactory*, Uint need, Uint xtra);
+
 Eterm* erts_reserve_heap(ErtsHeapFactory*, Uint need);
 void erts_factory_close(ErtsHeapFactory*);
 void erts_factory_trim_and_close(ErtsHeapFactory*,Eterm *brefs, Uint brefs_size);
 void erts_factory_undo(ErtsHeapFactory*);
 
+void erts_reserve_heap__(ErtsHeapFactory*, Uint need, Uint xtra); /* internal */
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE Eterm *
+erts_produce_heap(ErtsHeapFactory* factory, Uint need, Uint xtra)
+{
+    Eterm* res;
+
+    ASSERT((unsigned int)factory->mode > (unsigned int)FACTORY_CLOSED);
+    if (factory->hp + need > factory->hp_end) {
+	erts_reserve_heap__(factory, need, xtra);
+    }
+    res = factory->hp;
+    factory->hp += need;
+    return res;
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
 #ifdef CHECK_FOR_HOLES
 # define ERTS_FACTORY_HOLE_CHECK(f) do {    \
         /*if ((f)->p) erts_check_for_holes((f)->p);*/ \
@@ -215,6 +236,48 @@ typedef struct {
 #define ERL_MESSAGE_BUF_SZ 500
 
 typedef struct {
+    /*
+     * ** The signal queues private to a process. **
+     *
+     * These are:
+     * - an inner queue which only consists of
+     *   message signals
+     * - a middle queue which contains a mixture
+     *   of message and non-message signals
+     *
+     * When the process isn't processing signals in
+     * erts_proc_sig_handle_incoming():
+     * - the message queue corresponds to the inner
+     *   queue. Messages in the middle queue (and
+     *   in the outer queue) are in transit and
+     *   have NOT been received yet!
+     *
+     * When the process is processing signals in
+     * erts_proc_sig_handle_incoming():
+     * - the message queue corresponds to the inner
+     *   queue plus the head of the middle queue up
+     *   to the signal currently being processed.
+     *   Any messages further back in the middle queue
+     *   (and in the outer queue) are still in transit
+     *   and have NOT been received yet!
+     *
+     * In the general case the 'len' field of this
+     * structure does NOT correspond to the message
+     * queue length. When the process is inspected
+     * via process info it does however correspond
+     * to the message queue length, but this is a
+     * special case!
+     *
+     * When no process-info request is in transit to
+     * the process the 'len' field corresponds to
+     * the total amount of messages in inner and
+     * middle queues (which does NOT correspond to
+     * the message queue length). When process-info
+     * requests are in transit to the process, the
+     * usage of the 'len' field changes and is used
+     * as an offset which even might be negative.
+     */
+
     /* inner queue */
     ErtsMessage *first;
     ErtsMessage **last;  /* point to the last next pointer */
@@ -227,7 +290,7 @@ typedef struct {
 
     /* Common for inner and middle queue */
     ErtsMessage **saved_last;	/* saved last pointer */
-    Sint len; /* message queue length (inner+middle) */
+    Sint len; /* NOT message queue length (see above) */
 } ErtsSignalPrivQueues;
 
 typedef struct {
@@ -248,8 +311,7 @@ typedef struct erl_trace_message_queue__ {
 #define ERTS_RECV_MARK_SAVE(P)                                          \
     do {                                                                \
         erts_proc_lock((P), ERTS_PROC_LOCK_MSGQ);                       \
-        if ((P)->sig_inq.first)                                         \
-            erts_proc_sig_fetch((P));                                   \
+        erts_proc_sig_fetch((P));                                       \
         erts_proc_unlock((P), ERTS_PROC_LOCK_MSGQ);                     \
         if ((P)->sig_qs.cont) {                                         \
             (P)->sig_qs.saved_last = (P)->sig_qs.cont_last;             \
@@ -302,23 +364,6 @@ typedef struct erl_trace_message_queue__ {
 
 #endif
 
-
-/* Add message last in private message queue */
-#define LINK_MESSAGE_PRIVQ(p, first_msg, last_msg, num_msgs)            \
-    do {                                                                \
-        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), "before");             \
-        if ((p)->sig_qs.cont || ERTS_MSG_RECV_TRACED((p))) {            \
-            *(p)->sig_qs.cont_last = (first_msg);                       \
-            (p)->sig_qs.cont_last = (last_msg);                         \
-        }                                                               \
-        else {                                                          \
-            *(p)->sig_qs.last = (first_msg);                            \
-            (p)->sig_qs.last = (last_msg);                              \
-        }                                                               \
-        (p)->sig_qs.len += (num_msgs);                                  \
-        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), "after");              \
-    } while (0)
-
 /* Add message last_msg in message queue */
 #define LINK_MESSAGE(p, first_msg, last_msg, num_msgs) \
     do {                                                                \
@@ -333,12 +378,12 @@ typedef struct erl_trace_message_queue__ {
 #define UNLINK_MESSAGE(p,msgp)                                          \
     do {                                                                \
         ErtsMessage *mp__ = (msgp)->next;                               \
-        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), "before");             \
+        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), 0, "before");          \
         *(p)->sig_qs.save = mp__;                                       \
         (p)->sig_qs.len--;                                              \
         if (mp__ == NULL)                                               \
             (p)->sig_qs.last = (p)->sig_qs.save;                        \
-        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), "after");              \
+        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((p), 0, "after");           \
     } while(0)
 
 /*
diff --git a/erts/emulator/beam/erl_proc_sig_queue.c b/erts/emulator/beam/erl_proc_sig_queue.c
index b32ba1b2e6..bcc4fc6d9b 100644
--- a/erts/emulator/beam/erl_proc_sig_queue.c
+++ b/erts/emulator/beam/erl_proc_sig_queue.c
@@ -49,7 +49,7 @@
  * Note that not all signal are handled using this functionality!
  */
 
-#define ERTS_SIG_Q_OP_MAX 10
+#define ERTS_SIG_Q_OP_MAX 11
 
 #define ERTS_SIG_Q_OP_EXIT                      0
 #define ERTS_SIG_Q_OP_EXIT_LINKED               1
@@ -61,7 +61,8 @@
 #define ERTS_SIG_Q_OP_GROUP_LEADER              7
 #define ERTS_SIG_Q_OP_TRACE_CHANGE_STATE        8
 #define ERTS_SIG_Q_OP_PERSISTENT_MON_MSG        9
-#define ERTS_SIG_Q_OP_IS_ALIVE                  ERTS_SIG_Q_OP_MAX
+#define ERTS_SIG_Q_OP_IS_ALIVE                  10
+#define ERTS_SIG_Q_OP_PROCESS_INFO              ERTS_SIG_Q_OP_MAX
 
 #define ERTS_SIG_Q_TYPE_MAX (ERTS_MON_LNK_TYPE_MAX + 5)
 
@@ -76,46 +77,6 @@
 #define ERTS_SIG_Q_TYPE_ADJUST_TRACE_INFO \
     ERTS_SIG_Q_TYPE_MAX
 
-
-#define ERTS_SIG_Q_OP_BITS      8                      
-#define ERTS_SIG_Q_OP_SHIFT     0
-#define ERTS_SIG_Q_OP_MASK      ((1 << ERTS_SIG_Q_OP_BITS) - 1)
-
-#define ERTS_SIG_Q_TYPE_BITS    8
-#define ERTS_SIG_Q_TYPE_SHIFT   ERTS_SIG_Q_OP_BITS
-#define ERTS_SIG_Q_TYPE_MASK    ((1 << ERTS_SIG_Q_TYPE_BITS) - 1)
-
-#define ERTS_SIG_Q_NON_X_BITS__ (_HEADER_ARITY_OFFS \
-                                 + ERTS_SIG_Q_OP_BITS \
-                                 + ERTS_SIG_Q_TYPE_BITS)
-
-#define ERTS_SIG_Q_XTRA_BITS    (32 - ERTS_SIG_Q_NON_X_BITS__)
-#define ERTS_SIG_Q_XTRA_SHIFT   (ERTS_SIG_Q_OP_BITS \
-                                 + ERTS_SIG_Q_TYPE_BITS)
-#define ERTS_SIG_Q_XTRA_MASK    ((1 << ERTS_SIG_Q_XTRA_BITS) - 1)
-
-#define ERTS_PROC_SIG_OP(Tag) \
-    ((int) (_unchecked_thing_arityval((Tag)) \
-            >> ERTS_SIG_Q_OP_SHIFT) & ERTS_SIG_Q_OP_MASK)
-
-#define ERTS_PROC_SIG_TYPE(Tag) \
-    ((Uint16) (_unchecked_thing_arityval((Tag)) \
-               >> ERTS_SIG_Q_TYPE_SHIFT) & ERTS_SIG_Q_TYPE_MASK)
-
-#define ERTS_PROC_SIG_XTRA(Tag) \
-    ((Uint32) (_unchecked_thing_arityval((Tag)) \
-               >> ERTS_SIG_Q_XTRA_SHIFT) & ERTS_SIG_Q_XTRA_MASK)
-
-#define ERTS_PROC_SIG_MAKE_TAG(Op, Type, Xtra)                  \
-    (ASSERT(0 <= (Xtra) && (Xtra) <= ERTS_SIG_Q_XTRA_MASK),     \
-     _make_header((((Type) & ERTS_SIG_Q_TYPE_MASK)              \
-                   << ERTS_SIG_Q_TYPE_SHIFT)                    \
-                  | (((Op) & ERTS_SIG_Q_OP_MASK)                \
-                     << ERTS_SIG_Q_OP_SHIFT)                    \
-                  | (((Xtra) & ERTS_SIG_Q_XTRA_MASK)            \
-                     << ERTS_SIG_Q_XTRA_SHIFT),                 \
-                  _TAG_HEADER_EXTERNAL_PID))
-
 Process *ERTS_WRITE_UNLIKELY(erts_dirty_process_signal_handler);
 Process *ERTS_WRITE_UNLIKELY(erts_dirty_process_signal_handler_high);
 Process *ERTS_WRITE_UNLIKELY(erts_dirty_process_signal_handler_max);
@@ -123,7 +84,8 @@ Process *ERTS_WRITE_UNLIKELY(erts_dirty_process_signal_handler_max);
 void
 erts_proc_sig_queue_init(void)
 {
-    ERTS_CT_ASSERT(ERTS_SIG_Q_OP_MASK >= ERTS_SIG_Q_OP_MAX);
+    ERTS_CT_ASSERT(ERTS_SIG_Q_OP_MASK > ERTS_SIG_Q_OP_MAX);
+    ERTS_CT_ASSERT(ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK > ERTS_SIG_Q_OP_MAX);
     ERTS_CT_ASSERT(ERTS_SIG_Q_TYPE_MASK >= ERTS_SIG_Q_TYPE_MAX);
 }
 
@@ -191,6 +153,29 @@ typedef struct {
     Eterm requester;
 } ErtsIsAliveRequest;
 
+typedef struct {
+    ErtsSignalCommon common;
+    Sint refc;
+    Sint delayed_len;
+    Sint len_offset;
+} ErtsProcSigMsgQLenOffsetMarker;
+
+typedef struct {
+    ErtsSignalCommon common;
+    ErtsProcSigMsgQLenOffsetMarker marker;
+    Sint msgq_len_offset;
+    Eterm requester;
+    Eterm ref;
+    ErtsORefThing oref_thing;
+    Uint reserve_size;
+    Uint len;
+    int flags;
+    int item_ix[1]; /* of len size in reality... */
+} ErtsProcessInfoSig;
+
+#define ERTS_PROC_SIG_PI_MSGQ_LEN_IGNORE        ((Sint) -1)
+#define ERTS_PROC_SIG_PI_MSGQ_LEN_SYNC          ((Sint) -2)
+
 static int handle_msg_tracing(Process *c_p,
                               ErtsSigRecvTracing *tracing,
                               ErtsMessage ***next_nm_sig);
@@ -523,6 +508,9 @@ ensure_dirty_proc_handled(Eterm pid,
     }
 }
 
+static void
+check_push_msgq_len_offs_marker(Process *rp, ErtsSignal *sig);
+
 static int
 proc_queue_signal(Process *c_p, Eterm pid, ErtsSignal *sig, int op)
 {
@@ -559,6 +547,8 @@ proc_queue_signal(Process *c_p, Eterm pid, ErtsSignal *sig, int op)
         res = 0;
     else {
         state = enqueue_signals(rp, first, last, last_next, state);
+        if (ERTS_UNLIKELY(op == ERTS_SIG_Q_OP_PROCESS_INFO))
+            check_push_msgq_len_offs_marker(rp, sig);
         res = !0;
     }
 
@@ -620,31 +610,14 @@ maybe_elevate_sig_handling_prio(Process *c_p, Eterm other)
 }
 
 void
-erts_proc_sig_fetch(Process *proc)
+erts_proc_sig_fetch__(Process *proc)
 {
 #ifdef ERTS_PROC_SIG_HARD_DEBUG
     ErtsSignalPrivQueues sig_qs = proc->sig_qs;
     ErtsSignalInQueue sig_inq = proc->sig_inq;
 #endif
 
-    ERTS_LC_ASSERT(erts_thr_progress_is_blocking()
-                   || ERTS_PROC_IS_EXITING(proc)
-                   || ((erts_proc_lc_my_proc_locks(proc)
-                        & (ERTS_PROC_LOCK_MAIN
-                           | ERTS_PROC_LOCK_MSGQ))
-                       == (ERTS_PROC_LOCK_MAIN
-                           | ERTS_PROC_LOCK_MSGQ)));
-
-    if (!proc->sig_inq.first) {
-        ASSERT(proc->sig_inq.last == &proc->sig_inq.first);
-        ASSERT(proc->sig_inq.len == 0);
-        ASSERT(!proc->sig_inq.nmsigs.next);
-        ASSERT(!proc->sig_inq.nmsigs.last);
-        return;
-    }
-
-    ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(proc);
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc);
+    ASSERT(proc->sig_inq.first);
 
     if (!proc->sig_inq.nmsigs.next) {
         ASSERT(!(ERTS_PSFLG_SIG_IN_Q
@@ -720,7 +693,102 @@ erts_proc_sig_fetch(Process *proc)
     proc->sig_inq.last = &proc->sig_inq.first;
     proc->sig_inq.len = 0;
 
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc);
+}
+
+Sint
+erts_proc_sig_fetch_msgq_len_offs__(Process *proc)
+{
+    ErtsProcSigMsgQLenOffsetMarker *marker
+        = (ErtsProcSigMsgQLenOffsetMarker *) proc->sig_inq.first;
+
+    ASSERT(marker->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK);
+
+    if (marker->common.next) {
+        Sint len;
+
+        proc->flags |= F_DELAYED_PSIGQS_LEN;
+
+        /*
+         * Prevent update of sig_qs.len in fetch. These
+         * updates are done via process-info signal(s)
+         * instead...
+         */
+        len = proc->sig_inq.len;
+        marker->delayed_len += len;
+        marker->len_offset -= len;
+        proc->sig_inq.len = 0;
+
+        /*
+         * Temorarily remove marker during fetch...
+         */
+
+        proc->sig_inq.first = marker->common.next;
+        if (proc->sig_inq.last == &marker->common.next)
+            proc->sig_inq.last = &proc->sig_inq.first;
+        if (proc->sig_inq.nmsigs.next == &marker->common.next)
+            proc->sig_inq.nmsigs.next = &proc->sig_inq.first;
+        if (proc->sig_inq.nmsigs.last == &marker->common.next)
+            proc->sig_inq.nmsigs.last = &proc->sig_inq.first;
+
+        erts_proc_sig_fetch__(proc);
+
+        marker->common.next = NULL;
+        proc->sig_inq.first = (ErtsMessage *) marker;
+        proc->sig_inq.last = &marker->common.next;
+
+    }
+
+    return marker->delayed_len;
+}
+
+static ERTS_INLINE Sint
+proc_sig_privqs_len(Process *c_p, int have_qlock)
+{
+    Sint res = c_p->sig_qs.len;
+
+    ERTS_LC_ASSERT(!have_qlock
+                   ? (ERTS_PROC_LOCK_MAIN
+                      == erts_proc_lc_my_proc_locks(c_p))
+                   : ((ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_MAIN)
+                      == ((ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_MAIN)
+                          & erts_proc_lc_my_proc_locks(c_p))));
+
+    if (c_p->flags & F_DELAYED_PSIGQS_LEN) {
+        ErtsProcSigMsgQLenOffsetMarker *marker;
+
+        if (!have_qlock)
+            erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
+
+        marker = (ErtsProcSigMsgQLenOffsetMarker *) c_p->sig_inq.first;
+        ASSERT(marker);
+        ASSERT(marker->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK);
+
+        res += marker->delayed_len;
+
+        if (!have_qlock)
+            erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+    }
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+    {
+        Sint len = 0;
+        ERTS_FOREACH_SIG_PRIVQS(
+            c_p, mp,
+            {
+                if (ERTS_SIG_IS_MSG(mp))
+                    len++;
+            });
+        ERTS_ASSERT(res == len);
+    }
+#endif
+
+    return res;
+}
+
+Sint
+erts_proc_sig_privqs_len(Process *c_p)
+{
+    return proc_sig_privqs_len(c_p, 0);
 }
 
 static void do_seq_trace_output(Eterm to, Eterm token, Eterm msg);
@@ -1354,6 +1422,59 @@ erts_proc_sig_send_is_alive_request(Process *c_p, Eterm to, Eterm ref)
     }
 }
 
+int
+erts_proc_sig_send_process_info_request(Process *c_p,
+                                        Eterm to,
+                                        int *item_ix,
+                                        int len,
+                                        int need_msgq_len,
+                                        int flags,
+                                        Uint reserve_size,
+                                        Eterm ref)
+{
+    Uint size = sizeof(ErtsProcessInfoSig) + (len - 1) * sizeof(int);
+    ErtsProcessInfoSig *pis = erts_alloc(ERTS_ALC_T_SIG_DATA, size);
+    int res;
+
+    ASSERT(c_p);
+    ASSERT(item_ix);
+    ASSERT(len > 0);
+    ASSERT(is_internal_ordinary_ref(ref));
+
+    pis->common.tag = ERTS_PROC_SIG_MAKE_TAG(ERTS_SIG_Q_OP_PROCESS_INFO,
+                                             0, 0);
+
+    if (!need_msgq_len)
+        pis->msgq_len_offset = ERTS_PROC_SIG_PI_MSGQ_LEN_IGNORE;
+    else {
+        pis->msgq_len_offset = ERTS_PROC_SIG_PI_MSGQ_LEN_SYNC;
+        pis->marker.common.next = NULL;
+        pis->marker.common.specific.next = NULL;
+        pis->marker.common.tag = ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK;
+        pis->marker.refc = 0;
+        pis->marker.delayed_len = 0;
+        pis->marker.len_offset = 0;
+    }
+    pis->requester = c_p->common.id;
+    sys_memcpy((void *) &pis->oref_thing,
+               (void *) internal_ref_val(ref),
+               sizeof(ErtsORefThing));
+    pis->ref = make_internal_ref((char *) &pis->oref_thing);
+    pis->reserve_size = reserve_size;
+    pis->len = len;
+    pis->flags = flags;
+    sys_memcpy((void *) &pis->item_ix[0],
+               (void *) item_ix,
+               sizeof(int)*len);
+    res = proc_queue_signal(c_p, to, (ErtsSignal *) pis,
+                            ERTS_SIG_Q_OP_PROCESS_INFO);
+    if (res)
+        (void) maybe_elevate_sig_handling_prio(c_p, to);
+    else
+        erts_free(ERTS_ALC_T_SIG_DATA, pis);
+    return res;
+}       
+
 static void
 is_alive_response(Process *c_p, ErtsMessage *mp, int is_alive)
 {
@@ -1554,7 +1675,6 @@ remove_mq_m_sig(Process *c_p, ErtsMessage *sig, ErtsMessage **next_sig, ErtsMess
 {
     /* Removing message... */
     ASSERT(!ERTS_SIG_IS_NON_MSG(sig));
-    ASSERT(c_p->sig_qs.len > 0);
     c_p->sig_qs.len--;
     remove_mq_sig(c_p, sig, next_sig, next_nm_sig);
 }
@@ -1564,7 +1684,6 @@ remove_iq_m_sig(Process *c_p, ErtsMessage *sig, ErtsMessage **next_sig)
 {
     /* Removing message... */
     ASSERT(!ERTS_SIG_IS_NON_MSG(sig));
-    ASSERT(c_p->sig_qs.len > 0);
     c_p->sig_qs.len--;
     remove_iq_sig(c_p, sig, next_sig);
 }
@@ -2140,6 +2259,258 @@ handle_group_leader(Process *c_p, ErtsSigGroupLeader *sgl)
         destroy_sig_group_leader(sgl);
 }
 
+static void
+check_push_msgq_len_offs_marker(Process *rp, ErtsSignal *sig)
+{
+    ErtsProcessInfoSig *pisig = (ErtsProcessInfoSig *) sig;
+
+    ASSERT(ERTS_PROC_SIG_OP(sig->common.tag) == ERTS_SIG_Q_OP_PROCESS_INFO);
+
+    if (pisig->msgq_len_offset == ERTS_PROC_SIG_PI_MSGQ_LEN_SYNC) {
+        ErtsProcSigMsgQLenOffsetMarker *mrkr;
+        Sint len, msgq_len_offset;
+        ErtsMessage *first = rp->sig_inq.first;
+        ASSERT(first);
+        if (((ErtsSignal *) first)->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK)
+            mrkr = (ErtsProcSigMsgQLenOffsetMarker *) first;
+        else {
+            mrkr = &pisig->marker;
+
+            ASSERT(mrkr->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK);
+
+            mrkr->common.next = first;
+            ASSERT(rp->sig_inq.last != &rp->sig_inq.first);
+            if (rp->sig_inq.nmsigs.next == &rp->sig_inq.first)
+                rp->sig_inq.nmsigs.next = &mrkr->common.next;
+            if (rp->sig_inq.nmsigs.last == &rp->sig_inq.first)
+                rp->sig_inq.nmsigs.last = &mrkr->common.next;
+            rp->sig_inq.first = (ErtsMessage *) mrkr;
+        }
+
+        len = rp->sig_inq.len;
+        msgq_len_offset = len - mrkr->len_offset;
+
+        mrkr->len_offset = len;
+        mrkr->refc++;
+
+        pisig->msgq_len_offset = msgq_len_offset;
+
+#ifdef DEBUG
+        /* save pointer to used marker... */
+        pisig->marker.common.specific.attachment = (void *) mrkr;
+#endif
+
+    }
+}
+
+static void
+destroy_process_info_request(Process *c_p, ErtsProcessInfoSig *pisig)
+{
+    int dealloc_pisig = !0;
+
+    if (pisig->msgq_len_offset != ERTS_PROC_SIG_PI_MSGQ_LEN_IGNORE) {
+        Sint refc;
+        int dealloc_marker = 0;
+        ErtsProcSigMsgQLenOffsetMarker *marker;
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+        Sint delayed_len;
+#endif
+
+        ASSERT(pisig->msgq_len_offset >= 0);
+
+        erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
+        marker = (ErtsProcSigMsgQLenOffsetMarker *) c_p->sig_inq.first;
+        ASSERT(marker);
+        ASSERT(marker->refc > 0);
+        ASSERT(pisig->marker.common.specific.attachment == (void *) marker);
+
+        marker->delayed_len -= pisig->msgq_len_offset;
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+        delayed_len = marker->delayed_len;
+#endif
+
+        refc = --marker->refc;
+        if (refc) {
+            if (marker == &pisig->marker) {
+                /* Another signal using our marker... */
+                dealloc_pisig = 0;
+            }
+        }
+        else {
+            /* Marker unused; remove it... */
+            ASSERT(marker->delayed_len + marker->len_offset == 0);
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+            delayed_len += marker->len_offset;
+#endif
+            if (marker != &pisig->marker)
+                dealloc_marker = !0; /* used another signals marker... */
+            c_p->sig_inq.first = marker->common.next;
+            if (c_p->sig_inq.last == &marker->common.next)
+                c_p->sig_inq.last = &c_p->sig_inq.first;
+            if (c_p->sig_inq.nmsigs.next == &marker->common.next)
+                c_p->sig_inq.nmsigs.next = &c_p->sig_inq.first;
+            if (c_p->sig_inq.nmsigs.last == &marker->common.next)
+                c_p->sig_inq.nmsigs.last = &c_p->sig_inq.first;
+        }
+        erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ);
+
+        if (!refc) {
+            c_p->flags &= ~F_DELAYED_PSIGQS_LEN;
+            /* Adjust msg len of inner+middle queue */
+            ASSERT(marker->len_offset <= 0);
+            c_p->sig_qs.len -= marker->len_offset;
+
+            ASSERT(c_p->sig_qs.len >= 0);
+        }
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+        {
+            Sint len = 0;
+            ERTS_FOREACH_SIG_PRIVQS(
+                c_p, mp,
+                {
+                    if (ERTS_SIG_IS_MSG(mp))
+                        len++;
+                });
+            ERTS_ASSERT(c_p->sig_qs.len + delayed_len == len);
+        }
+#endif
+
+
+        if (dealloc_marker) {
+            ErtsProcessInfoSig *pisig2
+                = (ErtsProcessInfoSig *) (((char *) marker)
+                                          - offsetof(ErtsProcessInfoSig,
+                                                     marker));
+            erts_free(ERTS_ALC_T_SIG_DATA, pisig2);
+        }
+    }
+
+    if (dealloc_pisig)
+        erts_free(ERTS_ALC_T_SIG_DATA, pisig);
+}
+
+static int
+handle_process_info(Process *c_p, ErtsMessage *sig,
+                    ErtsMessage ***next_nm_sig, int is_alive)
+{
+    ErtsProcessInfoSig *pisig = (ErtsProcessInfoSig *) sig;
+    Uint reds = 0;
+    Process *rp;
+
+    if (pisig->msgq_len_offset != ERTS_PROC_SIG_PI_MSGQ_LEN_IGNORE) {
+        /*
+         * Request requires message queue data to be updated
+         * before inspection...
+         */
+
+        ASSERT(pisig->msgq_len_offset >= 0);
+        /*
+         * Update sig_qs.len to reflect the length
+         * of the message queue...
+         */
+        c_p->sig_qs.len += pisig->msgq_len_offset;
+
+        if (is_alive) {
+            /*
+             * Move messages part of message queue into inner
+             * signal queue...
+             */
+            if (*next_nm_sig != &c_p->sig_qs.cont) {
+                *c_p->sig_qs.last = c_p->sig_qs.cont;
+                c_p->sig_qs.last = *next_nm_sig;
+
+                c_p->sig_qs.cont = **next_nm_sig;
+                if (c_p->sig_qs.nmsigs.last == *next_nm_sig)
+                    c_p->sig_qs.nmsigs.last = &c_p->sig_qs.cont;
+                *next_nm_sig = &c_p->sig_qs.cont;
+                *c_p->sig_qs.last = NULL;
+            }
+
+            if (!pisig->common.specific.next) {
+                /*
+                 * No more signals in middle queue...
+                 *
+                 * Process-info 'status' needs sig-q
+                 * process flag to be updated in order
+                 * to show accurate result...
+                 */
+                erts_atomic32_read_band_nob(&c_p->state,
+                                            ~ERTS_PSFLG_SIG_Q);
+            }
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+            {
+                Sint len;
+                ErtsMessage *mp;
+                for (mp = c_p->sig_qs.first, len = 0; mp; mp = mp->next) {
+                    ERTS_ASSERT(ERTS_SIG_IS_MSG(mp));
+                    len++;
+                }
+                ERTS_ASSERT(c_p->sig_qs.len == len);
+            }
+#endif
+        }
+    }
+    if (is_alive)
+        remove_nm_sig(c_p, sig, next_nm_sig);
+
+    rp = erts_proc_lookup(pisig->requester);
+    ASSERT(c_p != rp);
+    if (rp) {
+        Eterm msg, res, ref, *hp;
+        ErtsProcLocks locks = 0;
+        ErtsHeapFactory hfact;
+        ErtsMessage *mp;
+        Uint reserve_size = 3 + sizeof(pisig->oref_thing)/sizeof(Eterm);
+
+        if (!is_alive) {
+            ErlOffHeap *ohp;
+            mp = erts_alloc_message_heap(rp, &locks, reserve_size, &hp, &ohp);
+            res = am_undefined;
+        }
+        else {
+            ErlHeapFragment *hfrag;
+
+            reserve_size += pisig->reserve_size;
+
+            mp = erts_alloc_message(0, NULL);
+            hfrag = new_message_buffer(reserve_size);
+            mp->data.heap_frag = hfrag;
+            erts_factory_selfcontained_message_init(&hfact, mp, &hfrag->mem[0]);
+
+            res = erts_process_info(c_p, &hfact, c_p, ERTS_PROC_LOCK_MAIN,
+                                    pisig->item_ix, pisig->len,
+                                    pisig->flags, reserve_size, &reds);
+
+            hp = erts_produce_heap(&hfact,
+                                   3 + sizeof(pisig->oref_thing)/sizeof(Eterm),
+                                   0);
+        }
+
+        sys_memcpy((void *) hp, (void *) &pisig->oref_thing,
+                   sizeof(pisig->oref_thing));
+        ref = make_internal_ref(hp);
+        hp += sizeof(pisig->oref_thing)/sizeof(Eterm);
+
+        msg = TUPLE2(hp, ref, res);
+
+        if (is_alive)
+            erts_factory_trim_and_close(&hfact, &msg, 1);
+
+        erts_queue_message(rp, locks, mp, msg, c_p->common.id);
+
+        if (!is_alive && locks)
+            erts_proc_unlock(rp, locks);
+    }
+
+    destroy_process_info_request(c_p, pisig);
+
+    if (reds > INT_MAX/8)
+        reds = INT_MAX/8;
+
+    return ((int) reds)*4 + 8;
+}
 
 /*
  * Called in order to handle incoming signals.
@@ -2155,7 +2526,7 @@ erts_proc_sig_handle_incoming(Process *c_p, erts_aint32_t *statep,
     ErtsMessage *sig, ***next_nm_sig;
     ErtsSigRecvTracing tracing;
 
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p);
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
     ERTS_LC_ASSERT(ERTS_PROC_LOCK_MAIN == erts_proc_lc_my_proc_locks(c_p));
 
     if (local_only)
@@ -2504,6 +2875,12 @@ 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_PROCESS_INFO:
+            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
+            handle_process_info(c_p, sig, next_nm_sig, !0);
+            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
+            break;
+
         case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE: {
             Uint16 type = ERTS_PROC_SIG_TYPE(tag);
 
@@ -2657,7 +3034,7 @@ stop: {
                 c_p->sig_qs.save = c_p->sig_qs.saved_last;
         }
 
-        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p);
+        ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
 
         *redsp = cnt/4 + 1;
 
@@ -2709,8 +3086,8 @@ erts_proc_sig_handle_exit(Process *c_p, int *redsp)
     int cnt, limit;
     ErtsMessage *sig, ***next_nm_sig;
 
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p);
-    ERTS_LC_ASSERT(!erts_proc_lc_my_proc_locks(c_p));
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
+    ERTS_LC_ASSERT(erts_proc_lc_my_proc_locks(c_p) == ERTS_PROC_LOCK_MAIN);
 
     ASSERT(!(ERTS_PSFLG_SIG_IN_Q & erts_atomic32_read_nob(&c_p->state)));
 
@@ -2817,9 +3194,11 @@ erts_proc_sig_handle_exit(Process *c_p, int *redsp)
         }
 
         case ERTS_SIG_Q_OP_IS_ALIVE:
-            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
             is_alive_response(c_p, sig, 0);
-            ERTS_PROC_SIG_HDBG_PRIV_CHKQ(c_p, &tracing, next_nm_sig);
+            break;
+
+        case ERTS_SIG_Q_OP_PROCESS_INFO:
+            handle_process_info(c_p, sig, next_nm_sig, 0);
             break;
 
         case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE:
@@ -3005,6 +3384,13 @@ erts_proc_sig_signal_size(ErtsSignal *sig)
         size = sizeof(ErtsSigTraceInfo);
         break;
 
+    case ERTS_SIG_Q_OP_PROCESS_INFO: {
+        ErtsProcessInfoSig *pisig = (ErtsProcessInfoSig *) sig;
+        size = sizeof(ErtsProcessInfoSig);
+        size += (pisig->len - 1) * sizeof(int);
+        break;
+    }
+
     default:
         ERTS_INTERNAL_ERROR("Unknown signal");
         break;
@@ -3060,8 +3446,7 @@ erts_proc_sig_receive_helper(Process *c_p,
             consumed_reds += 4;
             left_reds -= 4;
             erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ);
-            if (c_p->sig_inq.first)
-                erts_proc_sig_fetch(c_p);
+            erts_proc_sig_fetch(c_p);
             /*
              * Messages may have been moved directly to
              * inner queue...
@@ -3222,6 +3607,7 @@ handle_message_enqueued_tracing(Process *c_p,
         Sint tok_label = 0;
         Sint tok_lastcnt = 0;
         Sint tok_serial = 0;
+        Sint len = erts_proc_sig_privqs_len(c_p);
         Eterm seq_trace_token = ERL_MESSAGE_TOKEN(msg);
 
         if (seq_trace_token != NIL && is_tuple(seq_trace_token)) {
@@ -3233,7 +3619,7 @@ handle_message_enqueued_tracing(Process *c_p,
         DTRACE6(message_queued,
                 tracing->messages.receiver_name,
                 size_object(ERL_MESSAGE_TERM(msg)),
-                c_p->sig_qs.len,
+                len, /* This is NOT message queue len, but its something... */
                 tok_label, tok_lastcnt, tok_serial);
     }
 #endif
@@ -3305,24 +3691,11 @@ handle_msg_tracing(Process *c_p, ErtsSigRecvTracing *tracing,
     return 0;
 }
 
-/*
- * ERTS_INSPECT_MSGQ_KEEP_OH_MSGS == 0 will move off heap messages
- * into the heap of the inspected process if off_heap_message_queue
- * is false when process_info(_, messages) is called. That is, the
- * following GC will have more data in the rootset compared to the
- * scenario when process_info(_, messages) had not been called.
- *
- * ERTS_INSPECT_MSGQ_KEEP_OH_MSGS != 0 will keep off heap messages
- * off heap when process_info(_, messages) is called regardless of
- * the off_heap_message_queue setting of the process. That is, it
- * will change the following execution of the process as little as
- * possible.
- */
-#define ERTS_INSPECT_MSGQ_KEEP_OH_MSGS 1
-
 Uint
-erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
+erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
+                                       Process *rp,
                                        ErtsProcLocks rp_locks,
+                                       int info_on_self,
                                        ErtsMessageInfo *mip)
 {
     Uint tot_heap_size;
@@ -3331,9 +3704,8 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
     int self_on_heap;
 
     /*
-     * Prepare the message queue for inspection
-     * by process_info().
-     *
+     * Prepare the message queue (inner signal queue)
+     * for inspection by process_info().
      *
      * - Decode all messages on external format
      * - Remove all corrupt dist messages from queue
@@ -3342,20 +3714,11 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
      * - Return total heap size need for all messages
      *   that needs to be copied.
      *
-     * If ERTS_INSPECT_MSGQ_KEEP_OH_MSGS == 0:
-     * - In case off heap messages is disabled and
-     *   we are inspecting our own queue, move all
-     *   off heap data into the heap.
      */
 
-    /*
-     * All non-message signals *need* to have been
-     * handled before calling this functions...
-     */
-    ASSERT(!rp->sig_qs.cont);
-    ASSERT(!rp->sig_qs.nmsigs.next && !rp->sig_qs.nmsigs.last);
+    ASSERT(!info_on_self || c_p == rp);
 
-    self_on_heap = c_p == rp && !(c_p->flags & F_OFF_HEAP_MSGQ);
+    self_on_heap = info_on_self && !(c_p->flags & F_OFF_HEAP_MSGQ);
 
     tot_heap_size = 0;
     i = 0;
@@ -3369,8 +3732,7 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
 	if (ERTS_SIG_IS_EXTERNAL_MSG(mp)) {
 	    /* decode it... */
 	    if (mp->data.attached)
-		erts_decode_dist_message(rp, rp_locks, mp,
-					 ERTS_INSPECT_MSGQ_KEEP_OH_MSGS);
+		erts_decode_dist_message(rp, rp_locks, mp, !0);
 
 	    msg = ERL_MESSAGE_TERM(mp);
 
@@ -3396,44 +3758,11 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
 
 	ASSERT(is_value(msg));
 
-#if ERTS_INSPECT_MSGQ_KEEP_OH_MSGS
 	if (is_not_immed(msg) && (!self_on_heap || mp->data.attached)) {
 	    Uint sz = size_object(msg);
 	    mip[i].size = sz;
 	    tot_heap_size += sz;
 	}
-#else
-	if (self_on_heap) {
-	    if (mp->data.attached) {
-		ErtsMessage *tmp = NULL;
-		if (mp->data.attached != ERTS_MSG_COMBINED_HFRAG) {
-		    erts_link_mbuf_to_proc(rp, mp->data.heap_frag);
-		    mp->data.attached = NULL;
-		}
-		else {
-		    /*
-		     * Need to replace the message reference since
-		     * we will get references to the message data
-		     * from the heap...
-		     */
-		    ErtsMessage **mpp;
-		    tmp = erts_alloc_message(0, NULL);
-		    sys_memcpy((void *) tmp->m, (void *) mp->m,
-			       sizeof(Eterm)*ERL_MESSAGE_REF_ARRAY_SZ); 
-		    mpp = i == 0 ? &rp->sig_qs.first : &mip[i-1].msgp->next;
-		    erts_msgq_replace_msg_ref(&rp->msg, tmp, mpp);
-		    erts_save_message_in_proc(rp, mp);
-		    mp = tmp;
-		}
-	    }
-	}
-	else if (is_not_immed(msg)) {
-	    Uint sz = size_object(msg);
-	    mip[i].size = sz;
-	    tot_heap_size += sz;
-	}
-
-#endif
 
 	mip[i].msgp = mp;
 	i++;
@@ -3441,6 +3770,8 @@ erts_proc_sig_prep_msgq_for_inspection(Process *c_p, Process *rp,
 	mp = mp->next;
     }
 
+    ASSERT(c_p->sig_qs.len == i);
+
     return tot_heap_size;
 }
 
@@ -3477,11 +3808,11 @@ move_msg_to_heap(Process *c_p, ErtsMessage *mp)
 void
 erts_proc_sig_move_msgs_to_heap(Process *c_p)
 {
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p);
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
 
     ERTS_FOREACH_SIG_PRIVQS(c_p, sig, move_msg_to_heap(c_p, sig));
 
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p);
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(c_p, 0);
 }
 
 
@@ -3672,6 +4003,7 @@ erts_proc_sig_debug_foreach_sig(Process *c_p,
 
                 case ERTS_SIG_Q_OP_IS_ALIVE:
                 case ERTS_SIG_Q_OP_TRACE_CHANGE_STATE:
+                case ERTS_SIG_Q_OP_PROCESS_INFO:
                     break;
 
                 default:
@@ -3716,10 +4048,8 @@ chk_eterm(Process *c_p, int privq, ErtsMessage *mp, Eterm term)
     for (bp = erts_message_to_heap_frag(mp); bp; bp = bp->next) {
         if (bp->mem <= ptr && ptr < bp->mem + bp->used_size)
             return;
-        bp = bp->next;
     }
 
-    ERTS_ASSERT(privq);
     ASSERT(erts_dbg_within_proc(ptr, c_p, NULL));
 }
 
@@ -3742,6 +4072,12 @@ proc_sig_hdbg_check_queue(Process *proc,
     ErtsMessage **save = proc->sig_qs.save;
     ErtsMessage **saved_last = proc->sig_qs.saved_last;
 
+    if (!privq) {
+        ErtsSignal *sig = (ErtsSignal *) *sig_next;
+        if (sig->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK) {
+
+        }
+    }
 
     nm_next = sig_nm_next;
     nm_last = sig_nm_last;
@@ -3806,21 +4142,29 @@ proc_sig_hdbg_check_queue(Process *proc,
         if (!sig)
             break;
 
-        nm_sigs++;
+        nm_sig = (ErtsSignal *) sig;
 
-        ERTS_ASSERT(!last_nm_sig_found);
-        ERTS_ASSERT(ERTS_SIG_IS_NON_MSG(sig));
+        if (nm_sig->common.tag == ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK) {
+            ERTS_ASSERT(!privq);
+            ERTS_ASSERT(sig == *sig_next);
+        }
+        else {
+            nm_sigs++;
 
-        nm_sig = (ErtsSignal *) sig;
+            ERTS_ASSERT(!last_nm_sig_found);
+            ERTS_ASSERT(ERTS_SIG_IS_NON_MSG(sig));
+
+            ERTS_ASSERT(nm_next == next);
+
+            if (nm_last == next) {
+                ASSERT(!nm_sig->common.specific.next);
+                last_nm_sig_found = 1;
+            }
 
-        ERTS_ASSERT(nm_next == next);
+            nm_next = nm_sig->common.specific.next;
 
-        if (nm_last == next) {
-            ASSERT(!nm_sig->common.specific.next);
-            last_nm_sig_found = 1;
         }
 
-        nm_next = nm_sig->common.specific.next;
         next = &nm_sig->common.next;
         sig = nm_sig->common.next;
 
@@ -3875,10 +4219,10 @@ proc_sig_hdbg_check_queue(Process *proc,
 }
 
 void
-erts_proc_sig_hdbg_check_priv_queue(Process *p, char *what, char *file, int line)
+erts_proc_sig_hdbg_check_priv_queue(Process *p, int qlock, char *what, char *file, int line)
 {
     int found_saved_last = 0;
-    Sint len1, len2;
+    Sint len, len1, len2;
     ERTS_LC_ASSERT(erts_thr_progress_is_blocking()
                    || ERTS_PROC_IS_EXITING(p)
                    || (ERTS_PROC_LOCK_MAIN
@@ -3903,7 +4247,8 @@ erts_proc_sig_hdbg_check_priv_queue(Process *p, char *what, char *file, int line
                                      ERTS_PSFLG_SIG_Q);
     if (p->sig_qs.saved_last)
         ERTS_ASSERT(found_saved_last);
-    ERTS_ASSERT(p->sig_qs.len == len1 + len2);
+    len = proc_sig_privqs_len(p, qlock);
+    ERTS_ASSERT(len == len1 + len2);
 }
 
 void
diff --git a/erts/emulator/beam/erl_proc_sig_queue.h b/erts/emulator/beam/erl_proc_sig_queue.h
index 56fe3e683e..d250ad820f 100644
--- a/erts/emulator/beam/erl_proc_sig_queue.h
+++ b/erts/emulator/beam/erl_proc_sig_queue.h
@@ -32,6 +32,7 @@
  *              - Unlink
  *              - Group leader
  *              - Is process alive
+ *              - Process info request
  *              - Trace change
  *
  *              The signal queue consists of three parts:
@@ -78,6 +79,9 @@
 #if 0
 #  define ERTS_PROC_SIG_HARD_DEBUG
 #endif
+#if 0
+#  define ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+#endif
 
 struct erl_mesg;
 
@@ -95,22 +99,22 @@ typedef struct {
 #ifdef ERTS_PROC_SIG_HARD_DEBUG
 #  define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(P)       \
     ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__((P), "")
-#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P) \
-    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((P), "")
+#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P, QL) \
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__((P), (QL), "")
 #  define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__(P, What)   \
     erts_proc_sig_hdbg_check_in_queue((P), (What), __FILE__, __LINE__)
-#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, What)   \
-    erts_proc_sig_hdbg_check_priv_queue((P), (What), __FILE__, __LINE__)
+#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, QL, What)              \
+    erts_proc_sig_hdbg_check_priv_queue((P), (QL), (What), __FILE__, __LINE__)
 struct process;
-void erts_proc_sig_hdbg_check_priv_queue(struct process *c_p, char *what,
-                                         char *file, int line);
+void erts_proc_sig_hdbg_check_priv_queue(struct process *c_p, int qlock,
+                                         char *what, char *file, int line);
 void erts_proc_sig_hdbg_check_in_queue(struct process *c_p, char *what,
                                        char *file, int line);
 #else
 #  define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(P)
-#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P)
+#  define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(P, QL)
 #  define ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE__(P, What)
-#define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, What)
+#define ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE__(P, QL, What)
 #endif
 
 #endif
@@ -118,6 +122,57 @@ void erts_proc_sig_hdbg_check_in_queue(struct process *c_p, char *what,
 #if !defined(ERTS_PROC_SIG_QUEUE_H__) && !defined(ERTS_PROC_SIG_QUEUE_TYPE_ONLY)
 #define ERTS_PROC_SIG_QUEUE_H__
 
+#define ERTS_SIG_Q_OP_BITS      8                      
+#define ERTS_SIG_Q_OP_SHIFT     0
+#define ERTS_SIG_Q_OP_MASK      ((1 << ERTS_SIG_Q_OP_BITS) - 1)
+
+#define ERTS_SIG_Q_TYPE_BITS    8
+#define ERTS_SIG_Q_TYPE_SHIFT   ERTS_SIG_Q_OP_BITS
+#define ERTS_SIG_Q_TYPE_MASK    ((1 << ERTS_SIG_Q_TYPE_BITS) - 1)
+
+#define ERTS_SIG_Q_NON_X_BITS__ (_HEADER_ARITY_OFFS \
+                                 + ERTS_SIG_Q_OP_BITS \
+                                 + ERTS_SIG_Q_TYPE_BITS)
+
+#define ERTS_SIG_Q_XTRA_BITS    (32 - ERTS_SIG_Q_NON_X_BITS__)
+#define ERTS_SIG_Q_XTRA_SHIFT   (ERTS_SIG_Q_OP_BITS \
+                                 + ERTS_SIG_Q_TYPE_BITS)
+#define ERTS_SIG_Q_XTRA_MASK    ((1 << ERTS_SIG_Q_XTRA_BITS) - 1)
+
+
+#define ERTS_PROC_SIG_OP(Tag) \
+    ((int) (_unchecked_thing_arityval((Tag)) \
+            >> ERTS_SIG_Q_OP_SHIFT) & ERTS_SIG_Q_OP_MASK)
+
+#define ERTS_PROC_SIG_TYPE(Tag) \
+    ((Uint16) (_unchecked_thing_arityval((Tag)) \
+               >> ERTS_SIG_Q_TYPE_SHIFT) & ERTS_SIG_Q_TYPE_MASK)
+
+#define ERTS_PROC_SIG_XTRA(Tag) \
+    ((Uint32) (_unchecked_thing_arityval((Tag)) \
+               >> ERTS_SIG_Q_XTRA_SHIFT) & ERTS_SIG_Q_XTRA_MASK)
+
+#define ERTS_PROC_SIG_MAKE_TAG(Op, Type, Xtra)                  \
+    (ASSERT(0 <= (Xtra) && (Xtra) <= ERTS_SIG_Q_XTRA_MASK),     \
+     _make_header((((Type) & ERTS_SIG_Q_TYPE_MASK)              \
+                   << ERTS_SIG_Q_TYPE_SHIFT)                    \
+                  | (((Op) & ERTS_SIG_Q_OP_MASK)                \
+                     << ERTS_SIG_Q_OP_SHIFT)                    \
+                  | (((Xtra) & ERTS_SIG_Q_XTRA_MASK)            \
+                     << ERTS_SIG_Q_XTRA_SHIFT),                 \
+                  _TAG_HEADER_EXTERNAL_PID))
+
+
+/*
+ * ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK is not an actual
+ * operation. We keep it at the top of the OP range,
+ * larger than ERTS_SIG_Q_OP_MAX.
+ */
+#define ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK ERTS_SIG_Q_OP_MASK
+
+#define ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK \
+    ERTS_PROC_SIG_MAKE_TAG(ERTS_SIG_Q_OP_MSGQ_LEN_OFFS_MARK,0,0)
+
 struct dist_entry_;
 
 /*
@@ -451,6 +506,58 @@ void
 erts_proc_sig_send_is_alive_request(Process *c_p, Eterm to,
                                     Eterm ref);
 
+/**
+ *
+ * @brief Send a 'process info request' signal to a process.
+ *
+ * A response message '{Ref, Result}' is sent to the
+ * sender when performed where Ref is the reference passed
+ * as 'ref' argument, and Result corresponds to return result
+ * from erlang:process_info/[1,2].
+ *
+ * @param[in]     c_p           Pointer to process struct of
+ *                              currently executing process.
+ *                              NULL if signal arrived via
+ *                              distribution.
+ *
+ * @param[in]     to            Identifier of receiver.
+ *
+ * @param[in]     item_ix       Info index array to pass to
+ *                              erts_process_info()
+ *
+ * @param[in]     len           Lenght of info index array
+ *
+ * @param[in]     need_msgq_len Non-zero if message queue
+ *                              length is needed; otherwise,
+ *                              zero. If non-zero, sig_qs.len
+ *                              will be set to correspond
+ *                              to the message queue length
+ *                              before call to
+ *                              erts_process_info()
+ *
+ * @param[in]     flags         Flags to pass to
+ *                              erts_process_info()
+ *
+ * @param[in]     reserve_size  Heap size that is known to
+ *                              be needed. May not be correct
+ *                              though.
+ *
+ * @param[in]     ref           Reference to use in response
+ *                              message to the sending
+ *                              process (i.e., c_p).
+ *
+ */
+int
+erts_proc_sig_send_process_info_request(Process *c_p,
+                                        Eterm to,
+                                        int *item_ix,
+                                        int len,
+                                        int need_msgq_len,
+                                        int flags,
+                                        Uint reserve_size,
+                                        Eterm ref);
+
+
 /*
  * End of send operations of currently supported process signals.
  */
@@ -601,9 +708,30 @@ erts_proc_sig_receive_helper(Process *c_p, int fcalls,
  *
  * @param[in]   c_p             Pointer to process struct of
  *                              currently executing process.
+ * @returns                     Amount of message signals in
+ *                              inner plus middle signal
+ *                              queues after fetch completed
+ *                              (NOT the message queue
+ *                              length).
+ */
+ERTS_GLB_INLINE Sint erts_proc_sig_fetch(Process *p);
+
+/**
+ *
+ * @brief Get amount of messages in private queues
+ *
+ * @param[in]   c_p             Pointer to process struct of
+ *                              currently executing process.
  *
+ * @returns                     Amount of message signals in
+ *                              inner plus middle signal
+ *                              queues after fetch completed
+ *                              (NOT the message queue
+ *                              length).
  */
-void erts_proc_sig_fetch(Process *p);
+Sint
+erts_proc_sig_privqs_len(Process *c_p);
+
 
 typedef struct {
     Uint size;
@@ -623,17 +751,19 @@ typedef struct {
  *
  * @param[in]   rp_locks        Process locks held on 'rp'.
  *
+ * @param[in]   info_on_self    Integer set to non-zero value
+ *                              if caller is inspecting itself;
+ *                              otherwise, zero.
+ *
  * @param[in]   mip             Pointer to array of
  *                              ErtsMessageInfo structures.
- *                              
  */
-
 Uint erts_proc_sig_prep_msgq_for_inspection(Process *c_p,
                                             Process *rp,
                                             ErtsProcLocks rp_locks,
+                                            int info_on_self,
                                             ErtsMessageInfo *mip);
 
-
 /**
  *
  * @brief Move message data of messages in private queues to heap
@@ -687,4 +817,56 @@ extern Process *erts_dirty_process_signal_handler;
 extern Process *erts_dirty_process_signal_handler_high;
 extern Process *erts_dirty_process_signal_handler_max;
 
+void erts_proc_sig_fetch__(Process *proc);
+Sint erts_proc_sig_fetch_msgq_len_offs__(Process *proc);
+
+#if ERTS_GLB_INLINE_INCL_FUNC_DEF
+
+ERTS_GLB_INLINE Sint
+erts_proc_sig_fetch(Process *proc)
+{
+    Sint res = 0;
+    ErtsSignal *sig;
+
+    ERTS_LC_ASSERT(erts_thr_progress_is_blocking()
+                   || ERTS_PROC_IS_EXITING(proc)
+                   || ((erts_proc_lc_my_proc_locks(proc)
+                        & (ERTS_PROC_LOCK_MAIN
+                           | ERTS_PROC_LOCK_MSGQ))
+                       == (ERTS_PROC_LOCK_MAIN
+                           | ERTS_PROC_LOCK_MSGQ)));
+
+    ERTS_HDBG_CHECK_SIGNAL_IN_QUEUE(proc);
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc, !0);
+
+    sig = (ErtsSignal *) proc->sig_inq.first;
+    if (sig) {
+        if (ERTS_LIKELY(sig->common.tag != ERTS_PROC_SIG_MSGQ_LEN_OFFS_MARK))
+            erts_proc_sig_fetch__(proc);
+        else
+            res = erts_proc_sig_fetch_msgq_len_offs__(proc);
+    }
+
+    res += proc->sig_qs.len;
+
+    ERTS_HDBG_CHECK_SIGNAL_PRIV_QUEUE(proc, !0);
+
+#ifdef ERTS_PROC_SIG_HARD_DEBUG_SIGQ_MSG_LEN
+    {
+        Sint len = 0;
+        ERTS_FOREACH_SIG_PRIVQS(
+            proc, mp,
+            {
+                if (ERTS_SIG_IS_MSG(mp))
+                    len++;
+            });
+        ERTS_ASSERT(res == len);
+    }
+#endif
+
+    return res;
+}
+
+#endif /* ERTS_GLB_INLINE_INCL_FUNC_DEF */
+
 #endif /* ERTS_PROC_SIG_QUEUE_H__ */
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index ba0a9fbc79..71541786d0 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -10830,8 +10830,7 @@ erts_execute_dirty_system_task(Process *c_p)
 
     if (c_p->flags & F_DIRTY_GC_HIBERNATE) {
 	erts_proc_lock(c_p, ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS);
-	erts_proc_sig_fetch(c_p);
-	if (c_p->sig_qs.len)
+	if (erts_proc_sig_fetch(c_p))
             c_p->flags &= ~F_DIRTY_GC_HIBERNATE; /* operation aborted... */
         else {
 	    erts_proc_unlock(c_p, ERTS_PROC_LOCK_MSGQ|ERTS_PROC_LOCK_STATUS);
@@ -12411,12 +12410,14 @@ erts_proc_exit_handle_monitor(ErtsMonitor *mon, void *vctxt)
         case ERTS_MON_TYPE_PORT: {
 	    Port *prt;
             ASSERT(is_internal_port(mon->other.item));
+            erts_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
             prt = erts_id2port(mon->other.item);
 	    if (prt) {
                 erts_fire_port_monitor(prt, mon);
                 erts_port_release(prt);
                 mon = NULL;
             }
+            erts_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
             break;
         }
         case ERTS_MON_TYPE_RESOURCE:
@@ -12495,10 +12496,8 @@ erts_proc_exit_handle_monitor(ErtsMonitor *mon, void *vctxt)
             ASSERT(is_internal_port(mon->other.item));
             prt = erts_port_lookup_raw(mon->other.item);
             if (prt) {
-                erts_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
                 if (erts_port_demonitor(c_p, prt, mon) != ERTS_PORT_OP_DROPPED)
                     mon = NULL;
-                erts_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
             }
             break;
         }
@@ -12601,7 +12600,6 @@ erts_proc_exit_handle_link(ErtsLink *lnk, void *vctxt)
         if (!erts_link_dist_delete(dlnk))
             ldp = NULL;
 
-        erts_proc_lock(c_p, ERTS_PROC_LOCK_MAIN);
         code = erts_dsig_prepare(&dsd, dep, c_p, 0, ERTS_DSP_NO_LOCK, 0, 0);
         switch (code) {
         case ERTS_DSIG_PREP_CONNECTED:
@@ -12615,7 +12613,6 @@ erts_proc_exit_handle_link(ErtsLink *lnk, void *vctxt)
                 ASSERT(code == ERTS_DSIG_SEND_OK);
             }
         }
-        erts_proc_unlock(c_p, ERTS_PROC_LOCK_MAIN);
         break;
     }
     default:
@@ -12677,8 +12674,6 @@ erts_do_exit_process(Process* p, Eterm reason)
 
     cancel_suspend_of_suspendee(p, ERTS_PROC_LOCKS_ALL); 
 
-    erts_proc_sig_fetch(p);
-
     if (IS_TRACED(p)) {
 	if (IS_TRACED_FL(p, F_TRACE_CALLS))
 	    erts_schedule_time_break(p, ERTS_BP_CALL_TIME_SCHEDULE_EXITING);
@@ -12945,6 +12940,12 @@ erts_continue_exit_process(Process *p)
     pectxt.c_p = p;
     pectxt.reason = reason;
 
+    erts_proc_lock(p, ERTS_PROC_LOCK_MAIN|ERTS_PROC_LOCK_MSGQ);
+
+    erts_proc_sig_fetch(p);
+
+    erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+
     if (links) {
         erts_link_tree_foreach_delete(&links,
                                       erts_proc_exit_handle_link,
@@ -12966,7 +12967,6 @@ erts_continue_exit_process(Process *p)
         ASSERT(!lt_monitors);
     }
 
-    erts_proc_sig_fetch(p);
     /*
      * erts_proc_sig_handle_exit() implements yielding.
      * However, this function cannot handle it yet... loop
@@ -12978,7 +12978,6 @@ erts_continue_exit_process(Process *p)
             break;
     }
 
-    erts_proc_lock(p, ERTS_PROC_LOCK_MAIN);
     ERTS_CHK_HAVE_ONLY_MAIN_PROC_LOCK(p);
 
     erts_flush_trace_messages(p, ERTS_PROC_LOCK_MAIN);
@@ -13015,27 +13014,41 @@ erts_continue_exit_process(Process *p)
 }
 
 Process *
-erts_try_lock_sig_free_proc(Eterm pid, ErtsProcLocks locks)
+erts_try_lock_sig_free_proc(Eterm pid, ErtsProcLocks locks,
+                            erts_aint32_t *statep)
 {
     Process *rp = erts_proc_lookup_raw(pid);
     erts_aint32_t state;
 
-    if (!rp)
+    if (!rp) {
+        if (statep)
+            *statep = ERTS_PSFLG_EXITING|ERTS_PSFLG_FREE;
         return NULL;
+    }
 
     ERTS_LC_ASSERT(!erts_proc_lc_my_proc_locks(rp));
 
     state = erts_atomic32_read_nob(&rp->state);
-    if (state & ERTS_PSFLG_EXITING)
+    if (statep)
+        *statep = state;
+
+    if (state & ERTS_PSFLG_FREE)
         return NULL;
 
     if (state & (ERTS_PSFLG_SIG_IN_Q|ERTS_PSFLG_SIG_Q))
         return ERTS_PROC_LOCK_BUSY;
+
+    if (!locks)
+        return rp;
+
     if (erts_proc_trylock(rp, locks) == EBUSY)
         return ERTS_PROC_LOCK_BUSY;
 
     state = erts_atomic32_read_nob(&rp->state);
-    if (state & ERTS_PSFLG_EXITING) {
+    if (statep)
+        *statep = state;
+
+    if (state & ERTS_PSFLG_FREE) {
         erts_proc_unlock(rp, locks);
         return NULL;
     }
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index f7c6c3435b..e232776016 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1391,6 +1391,7 @@ extern int erts_system_profile_ts_type;
 #define F_LOCAL_SIGS_ONLY    (1 << 26)
 #define F_TRAP_EXIT          (1 << 27) /* Trapping exit */
 #define F_DEFERRED_SAVED_LAST (1 << 28)
+#define F_DELAYED_PSIGQS_LEN (1 << 29)
 
 /*
  * F_DISABLE_GC and F_DELAY_GC are similar. Both will prevent
@@ -1817,6 +1818,10 @@ void erts_print_scheduler_info(fmtfn_t to, void *to_arg, ErtsSchedulerData *esdp
 void erts_print_run_queue_info(fmtfn_t, void *to_arg, ErtsRunQueue*);
 void erts_dump_extended_process_state(fmtfn_t to, void *to_arg, erts_aint32_t psflg);
 void erts_dump_process_state(fmtfn_t to, void *to_arg, erts_aint32_t psflg);
+Eterm erts_process_info(Process *c_p, ErtsHeapFactory *hfact,
+                        Process *rp, ErtsProcLocks rp_locks,
+                        int *item_ix, int item_ix_len,
+                        int flags, Uint reserve_size, Uint *reds);
 
 typedef struct {
     Process *c_p;
@@ -1855,7 +1860,7 @@ Uint erts_debug_nbalance(void);
 
 int erts_debug_wait_completed(Process *c_p, int flags);
 
-Uint erts_process_memory(Process *c_p, int incl_msg_inq);
+Uint erts_process_memory(Process *c_p, int include_sigs_in_transit);
 
 #ifdef ERTS_DO_VERIFY_UNUSED_TEMP_ALLOC
 #  define ERTS_VERIFY_UNUSED_TEMP_ALLOC(P)					\
@@ -2595,7 +2600,8 @@ ERTS_TIME2REDS_IMPL__(ErtsMonotonicTime start, ErtsMonotonicTime end)
 #endif
 
 Process *erts_try_lock_sig_free_proc(Eterm pid,
-                                     ErtsProcLocks locks);
+                                     ErtsProcLocks locks,
+                                     erts_aint32_t *statep);
 
 Process *erts_pid2proc_not_running(Process *,
 				   ErtsProcLocks,
diff --git a/erts/emulator/beam/erl_process_dict.c b/erts/emulator/beam/erl_process_dict.c
index aee88841ae..38be3938cd 100644
--- a/erts/emulator/beam/erl_process_dict.c
+++ b/erts/emulator/beam/erl_process_dict.c
@@ -239,39 +239,70 @@ erts_erase_dicts(Process *p)
 /* 
  * Called from process_info/1,2.
  */
-Eterm erts_dictionary_copy(Process *p, ProcDict *pd) 
+Eterm erts_dictionary_copy(ErtsHeapFactory *hfact, ProcDict *pd, Uint reserve_size) 
 {
-    Eterm* hp;
-    Eterm* heap_start;
-    Eterm res = NIL;
-    Eterm tmp, tmp2;
+    Eterm res;
     unsigned int i, num;
+    Uint *sz;
+    Uint szi, rsz = reserve_size;
 
-    if (pd == NULL) {
-	return res;
-    }
+    if (pd == NULL)
+	return NIL;
 
     PD_CHECK(pd);
     num = HASH_RANGE(pd);
-    heap_start = hp = (Eterm *) erts_alloc(ERTS_ALC_T_TMP,
-					   sizeof(Eterm) * pd->numElements * 2);
-    for (i = 0; i < num; ++i) {
-	tmp = ARRAY_GET(pd, i);
+    sz = (Uint *) erts_alloc(ERTS_ALC_T_TMP, sizeof(Uint) * pd->numElements);
+
+    for (i = 0, szi = 0; i < num; ++i) {
+	Eterm tmp = ARRAY_GET(pd, i);
 	if (is_boxed(tmp)) {
+            Uint size;
 	    ASSERT(is_tuple(tmp));
-	    res = CONS(hp, tmp, res);
-	    hp += 2;
-	} else if (is_list(tmp)) {
+            size = size_object(tmp) + 2;
+            sz[szi++] = size;
+            rsz += size;
+	}
+        else if (is_list(tmp)) {
 	    while (tmp != NIL) {
-		tmp2 = TCAR(tmp);
-		res = CONS(hp, tmp2, res);
-		hp += 2;
+                Uint size = size_object(TCAR(tmp)) + 2;
+                sz[szi++] = size;
+                rsz += size;
+    		tmp = TCDR(tmp);
+	    }
+	}
+    }
+
+    res = NIL;
+
+    for (i = 0, szi = 0; i < num; ++i) {
+	Eterm tmp = ARRAY_GET(pd, i);
+	if (is_boxed(tmp)) {
+            Uint size;
+            Eterm el, *hp;
+	    ASSERT(is_tuple(tmp));
+            size = sz[szi++];
+            rsz -= size;
+            hp = erts_produce_heap(hfact, size, rsz);
+            el = copy_struct(tmp, size-2, &hp, hfact->off_heap);
+	    res = CONS(hp, el, res);
+	}
+        else if (is_list(tmp)) {
+	    while (tmp != NIL) {
+                Uint size = sz[szi++];
+                Eterm el, *hp;
+                rsz -= size;
+                hp = erts_produce_heap(hfact, size, rsz);
+                el = copy_struct(TCAR(tmp), size-2, &hp, hfact->off_heap);
+		res = CONS(hp, el, res);
 		tmp = TCDR(tmp);
 	    }
 	}
     }
-    res = copy_object(res, p);
-    erts_free(ERTS_ALC_T_TMP, (void *) heap_start);
+
+    ASSERT(rsz == reserve_size);
+
+    erts_free(ERTS_ALC_T_TMP, sz);
+
     return res;
 }
 
diff --git a/erts/emulator/beam/erl_process_dict.h b/erts/emulator/beam/erl_process_dict.h
index ab58f3c239..b89b387f5a 100644
--- a/erts/emulator/beam/erl_process_dict.h
+++ b/erts/emulator/beam/erl_process_dict.h
@@ -40,7 +40,7 @@ void erts_erase_dicts(struct process *p);
 void erts_dictionary_dump(fmtfn_t to, void *to_arg, ProcDict *pd);
 void erts_deep_dictionary_dump(fmtfn_t to, void *to_arg,
 			       ProcDict* pd, void (*cb)(fmtfn_t, void *, Eterm obj));
-Eterm erts_dictionary_copy(struct process *p, ProcDict *pd);
+Eterm erts_dictionary_copy(ErtsHeapFactory *hfact, ProcDict *pd, Uint reserve_size);
 
 Eterm erts_pd_hash_get(struct process *p, Eterm id);
 Uint32 erts_pd_make_hx(Eterm key);
diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index 5db276ec7f..243db4c734 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -109,56 +109,77 @@ link_size(ErtsMonitor *lnk, void *vsize)
     *((Uint *) vsize) += erts_link_size(lnk);
 }
 
-Uint erts_process_memory(Process *p, int incl_msg_inq) {
-  Uint size = 0;
-  struct saved_calls *scb;
-  size += sizeof(Process);
-
-  if (incl_msg_inq) {
-      erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
-      erts_proc_sig_fetch(p);
-      erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
-  }
-
-  erts_link_tree_foreach(ERTS_P_LINKS(p),
-                         link_size, (void *) &size);
-  erts_monitor_tree_foreach(ERTS_P_MONITORS(p),
-                            monitor_size, (void *) &size);
-  erts_monitor_list_foreach(ERTS_P_LT_MONITORS(p),
-                            monitor_size, (void *) &size);
-  size += (p->heap_sz + p->mbuf_sz) * sizeof(Eterm);
-  if (p->abandoned_heap)
-      size += (p->hend - p->heap) * sizeof(Eterm);
-  if (p->old_hend && p->old_heap)
-    size += (p->old_hend - p->old_heap) * sizeof(Eterm);
-
-
-  size += p->sig_qs.len * sizeof(ErtsMessage);
-
-  ERTS_FOREACH_SIG_PRIVQS(
-      p, mp,
-      {
-          if (ERTS_SIG_IS_NON_MSG((ErtsSignal *) mp))
-              size += erts_proc_sig_signal_size((ErtsSignal *) mp);
-          else if (mp->data.attached)
-              size += erts_msg_attached_data_size(mp) * sizeof(Eterm);
-      });
-
-  if (p->arg_reg != p->def_arg_reg) {
-    size += p->arity * sizeof(p->arg_reg[0]);
-  }
-
-  if (erts_atomic_read_nob(&p->psd) != (erts_aint_t) NULL)
-    size += sizeof(ErtsPSD);
-
-  scb = ERTS_PROC_GET_SAVED_CALLS_BUF(p);
-  if (scb) {
-    size += (sizeof(struct saved_calls)
-	     + (scb->len-1) * sizeof(scb->ct[0]));
-  }
-
-  size += erts_dicts_mem_size(p);
-  return size;
+Uint erts_process_memory(Process *p, int include_sigs_in_transit)
+{
+    Uint size = 0;
+    struct saved_calls *scb;
+
+    size += sizeof(Process);
+
+    erts_link_tree_foreach(ERTS_P_LINKS(p),
+                           link_size, (void *) &size);
+    erts_monitor_tree_foreach(ERTS_P_MONITORS(p),
+                              monitor_size, (void *) &size);
+    erts_monitor_list_foreach(ERTS_P_LT_MONITORS(p),
+                              monitor_size, (void *) &size);
+    size += (p->heap_sz + p->mbuf_sz) * sizeof(Eterm);
+    if (p->abandoned_heap)
+        size += (p->hend - p->heap) * sizeof(Eterm);
+    if (p->old_hend && p->old_heap)
+        size += (p->old_hend - p->old_heap) * sizeof(Eterm);
+
+    if (!include_sigs_in_transit) {
+        /*
+         * Size of message queue!
+         *
+         * Note that this assumes that any part of message
+         * queue located in middle queue have been moved
+         * into the inner queue prior to this call.
+         * process_info() management ensures this is done-
+         */
+        ErtsMessage *mp;
+        for (mp = p->sig_qs.first; mp; mp = mp->next) {
+            ASSERT(ERTS_SIG_IS_MSG((ErtsSignal *) mp));
+            size += sizeof(ErtsMessage);
+            if (mp->data.attached)
+                size += erts_msg_attached_data_size(mp) * sizeof(Eterm);
+        }
+    }
+    else {
+        /*
+         * Size of message queue plus size of all signals
+         * in transit to the process!
+         */
+        erts_proc_lock(p, ERTS_PROC_LOCK_MSGQ);
+        erts_proc_sig_fetch(p);
+        erts_proc_unlock(p, ERTS_PROC_LOCK_MSGQ);
+
+        ERTS_FOREACH_SIG_PRIVQS(
+            p, mp,
+            {
+                size += sizeof(ErtsMessage);
+                if (ERTS_SIG_IS_NON_MSG((ErtsSignal *) mp))
+                    size += erts_proc_sig_signal_size((ErtsSignal *) mp);
+                else if (mp->data.attached)
+                    size += erts_msg_attached_data_size(mp) * sizeof(Eterm);
+            });
+    }
+
+    if (p->arg_reg != p->def_arg_reg) {
+        size += p->arity * sizeof(p->arg_reg[0]);
+    }
+
+    if (erts_atomic_read_nob(&p->psd) != (erts_aint_t) NULL)
+        size += sizeof(ErtsPSD);
+
+    scb = ERTS_PROC_GET_SAVED_CALLS_BUF(p);
+    if (scb) {
+        size += (sizeof(struct saved_calls)
+                 + (scb->len-1) * sizeof(scb->ct[0]));
+    }
+
+    size += erts_dicts_mem_size(p);
+    return size;
 }
 
 static ERTS_INLINE void
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 7724231cd5..256670ff22 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -860,6 +860,8 @@ void erts_emasculate_writable_binary(ProcBin* pb);
 Eterm erts_new_heap_binary(Process *p, byte *buf, int len, byte** datap);
 Eterm erts_new_mso_binary(Process*, byte*, Uint);
 Eterm new_binary(Process*, byte*, Uint);
+Eterm erts_heap_factory_new_binary(ErtsHeapFactory *hfact, byte *buf,
+                                   Uint len, Uint reserve_size);
 Eterm erts_realloc_binary(Eterm bin, size_t size);
 Eterm erts_build_proc_bin(ErlOffHeap*, Eterm*, Binary*);
 
diff --git a/erts/emulator/beam/msg_instrs.tab b/erts/emulator/beam/msg_instrs.tab
index 289436da6f..26bea0efc6 100644
--- a/erts/emulator/beam/msg_instrs.tab
+++ b/erts/emulator/beam/msg_instrs.tab
@@ -225,6 +225,7 @@ remove_message() {
         Sint tok_label = 0;
         Sint tok_lastcnt = 0;
         Sint tok_serial = 0;
+        Sint len = erts_proc_sig_privqs_len(c_p);
 
         dtrace_proc_str(c_p, receiver_name);
         token2 = SEQ_TRACE_TOKEN(c_p);
@@ -235,7 +236,8 @@ remove_message() {
         }
         DTRACE6(message_receive,
                 receiver_name, size_object(ERL_MESSAGE_TERM(msgp)),
-                c_p->sig_qs.len - 1, tok_label, tok_lastcnt, tok_serial);
+                len, /* This is NOT message queue len, but its something... */
+                tok_label, tok_lastcnt, tok_serial);
     }
 #endif
     UNLINK_MESSAGE(c_p, msgp);
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 4bf60619ba..188e02eff8 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -59,6 +59,7 @@
 #endif
 #define ERTS_WANT_NFUNC_SCHED_INTERNALS__
 #include "erl_nfunc_sched.h"
+#include "erl_proc_sig_queue.h"
 
 #undef M_TRIM_THRESHOLD
 #undef M_TOP_PAD
diff --git a/erts/emulator/test/bif_SUITE.erl b/erts/emulator/test/bif_SUITE.erl
index 22706ae8b1..32bfcd5520 100644
--- a/erts/emulator/test/bif_SUITE.erl
+++ b/erts/emulator/test/bif_SUITE.erl
@@ -35,7 +35,8 @@
 	 is_builtin/1, error_stacktrace/1,
 	 error_stacktrace_during_call_trace/1,
          group_leader_prio/1, group_leader_prio_dirty/1,
-         is_process_alive/1]).
+         is_process_alive/1,
+         process_info_blast/1]).
 
 suite() ->
     [{ct_hooks,[ts_install_cth]},
@@ -50,7 +51,7 @@ 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].
+     is_process_alive, process_info_blast].
 
 %% Uses erlang:display to test that erts_printf does not do deep recursion
 display(Config) when is_list(Config) ->
@@ -1099,6 +1100,76 @@ is_process_alive(Config) when is_list(Config) ->
                   Ps),
     ok.
 
+process_info_blast(Config) when is_list(Config) ->
+    Tester = self(),
+    NoAttackers = 1000,
+    NoAL = lists:seq(1, NoAttackers),
+    Consume = make_ref(),
+    Victim = spawn_link(fun () ->
+                                receive
+                                    Consume ->
+                                        ok
+                                end,
+                                consume_msgs()
+                        end),
+    AFun = fun () ->
+                   Victim ! hej,
+                   Res = process_info(Victim, message_queue_len),
+                   Tester ! {self(), Res}
+           end,
+    Attackers0 = lists:map(fun (_) ->
+                                   spawn_link(AFun)
+                           end,
+                           NoAL),
+    lists:foreach(fun (A) ->
+                          receive
+                              {A, Res} ->
+                                  case Res of
+                                      {message_queue_len, Len} when Len > 0, Len =< NoAttackers ->
+                                          Len;
+                                      Error ->
+                                          exit({unexpected, Error})
+                                  end
+                          end
+                  end,
+                  Attackers0),
+    Attackers1 = lists:map(fun (_) ->
+                                   spawn_link(AFun)
+                           end,
+                           NoAL),
+    Victim ! Consume,
+    lists:foreach(fun (A) ->
+                          receive
+                              {A, Res} ->
+                                  case Res of
+                                      {message_queue_len, Len} when Len >= 0, Len =< 2*NoAttackers+1 ->
+                                          ok;
+                                      undefined ->
+                                          ok;
+                                      Error ->
+                                          exit({unexpected, Error})
+                                  end
+                          end
+                  end,
+                  Attackers1),
+    KillFun = fun (P) ->
+                      unlink(P),
+                      exit(P, kill),
+                      false = erlang:is_process_alive(P)
+              end,
+    lists:foreach(fun (A) -> KillFun(A) end, Attackers0),
+    lists:foreach(fun (A) -> KillFun(A) end, Attackers1),
+    KillFun(Victim),
+    ok.
+
+consume_msgs() ->
+    receive
+        _ ->
+            consume_msgs()
+    after 0 ->
+              ok
+    end.
+                              
 %% helpers
     
 id(I) -> I.
diff --git a/erts/emulator/test/process_SUITE.erl b/erts/emulator/test/process_SUITE.erl
index 7eff786e8b..46ece531a8 100644
--- a/erts/emulator/test/process_SUITE.erl
+++ b/erts/emulator/test/process_SUITE.erl
@@ -42,6 +42,8 @@
 	 process_info_lock_reschedule2/1,
 	 process_info_lock_reschedule3/1,
          process_info_garbage_collection/1,
+         process_info_smoke_all/1,
+         process_info_status_handled_signal/1,
 	 bump_reductions/1, low_prio/1, binary_owner/1, yield/1, yield2/1,
 	 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,
@@ -79,6 +81,8 @@ all() ->
      process_info_lock_reschedule2,
      process_info_lock_reschedule3,
      process_info_garbage_collection,
+     process_info_smoke_all,
+     process_info_status_handled_signal,
      bump_reductions, low_prio, yield, yield2, otp_4725,
      bad_register, garbage_collect, process_info_messages,
      process_flag_badarg, process_flag_heap_size,
@@ -510,14 +514,20 @@ pio_current_location(N, Pid, Pi, Looper) ->
     case Where of
 	{erlang,process_info,2,[]} ->
 	    pio_current_location(N-1, Pid, Pi+1, Looper);
+	{erts_internal,await_result,1, Loc} when is_list(Loc) ->
+	    pio_current_location(N-1, Pid, Pi+1, Looper);
 	{?MODULE,process_info_looper,1,Loc} when is_list(Loc) ->
-	    pio_current_location(N-1, Pid, Pi, Looper+1)
+	    pio_current_location(N-1, Pid, Pi, Looper+1);
+	_ ->
+	    exit({unexpected_location, Where})
     end.
 
 pio_current_stacktrace() ->
     L = [begin
-	     {current_stacktrace,Stk} = process_info(P, current_stacktrace),
-	     {P,Stk}
+	     case process_info(P, current_stacktrace) of
+                 {current_stacktrace, Stk} -> {P,Stk};
+                 undefined -> {P, []}
+             end
 	 end || P <- processes()],
     [erlang:garbage_collect(P) || {P,_} <- L],
     erlang:garbage_collect(),
@@ -973,6 +983,106 @@ process_info_garbage_collection(_Config) ->
 gv(Key,List) ->
     proplists:get_value(Key,List).
 
+process_info_smoke_all_tester() ->
+    register(process_info_smoke_all_tester, self()),
+    put(ets_ref, ets:new(blupp, [])),
+    put(binary, [list_to_binary(lists:duplicate(1000, 1)),
+                 list_to_binary(lists:duplicate(1000, 2))]),
+    process_info_smoke_all_tester_loop().
+
+process_info_smoke_all_tester_loop() ->
+    receive
+        {other_process, Pid} ->
+            case get(procs) of
+                undefined -> put(procs, [Pid]);
+                Procs -> put(procs, [Pid|Procs])
+            end,
+            erlang:monitor(process, Pid),
+            link(Pid),
+            process_info_smoke_all_tester_loop()
+    end.
+
+process_info_smoke_all(Config) when is_list(Config) ->
+    AllPIOptions = [registered_name,
+                    current_function,
+                    initial_call,
+                    messages,
+                    message_queue_len,
+                    links,
+                    monitors,
+                    monitored_by,
+                    dictionary,
+                    trap_exit,
+                    error_handler,
+                    heap_size,
+                    stack_size,
+                    memory,
+                    garbage_collection,
+                    group_leader,
+                    reductions,
+                    priority,
+                    trace,
+                    binary,
+                    sequential_trace_token,
+                    catchlevel,
+                    backtrace,
+                    last_calls,
+                    total_heap_size,
+                    suspending,
+                    min_heap_size,
+                    min_bin_vheap_size,
+                    max_heap_size,
+                    current_location,
+                    current_stacktrace,
+                    message_queue_data,
+                    garbage_collection_info,
+                    magic_ref,
+                    fullsweep_after],
+
+    {ok, Node} = start_node(Config, ""),
+    RP = spawn_link(Node, fun process_info_smoke_all_tester/0),
+    LP = spawn_link(fun process_info_smoke_all_tester/0),
+    RP ! {other_process, LP},
+    LP ! {other_process, RP},
+    LP ! {other_process, self()},
+    LP ! ets:new(blapp, []),
+    LP ! ets:new(blipp, []),
+    LP ! list_to_binary(lists:duplicate(1000, 3)),
+    receive after 1000 -> ok end,
+    _MLP = erlang:monitor(process, LP),
+    true = is_process_alive(LP),
+    PI = process_info(LP, AllPIOptions),
+    io:format("~p~n", [PI]),
+    garbage_collect(),
+    unlink(RP),
+    unlink(LP),
+    exit(RP, kill),
+    exit(LP, kill),
+    false = is_process_alive(LP),
+    stop_node(Node),
+    ok.
+
+process_info_status_handled_signal(Config) when is_list(Config) ->
+    P = spawn_link(fun () ->
+                           receive after infinity -> ok end
+                   end),
+    wait_until(fun () ->
+                       process_info(P, status) == {status, waiting}
+               end),
+    %%
+    %% The 'messages' option will force a process-info-request
+    %% signal to be scheduled on the process. Ensure that status
+    %% 'waiting' is reported even though it is actually running
+    %% when handling the request. We want it to report the status
+    %% it would have had if it had not been handling the
+    %% process-info-request...
+    %%
+    [{status, waiting}, {messages, []}] = process_info(P, [status, messages]),
+    unlink(P),
+    exit(P, kill),
+    false = erlang:is_process_alive(P),
+    ok.
+
 %% Tests erlang:bump_reductions/1.
 bump_reductions(Config) when is_list(Config) ->
     erlang:garbage_collect(),