erts: Remove ets traversal yielding if heap fragment

Many heap fragments do no longer make the GC slow.

Even worse, we are not guaranteed that a yield will provoke a GC
removing the fragments, which might lead to a one-yield-per-bucket
scenario if the heap fragment(s) still remains after each yield.

3 files changed, 12 insertions, 25 deletions

diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 4050fb6146..43d99db0b2 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -4459,7 +4459,16 @@ BIF_RETTYPE erts_debug_set_internal_state_2(BIF_ALIST_2)
                                             refbin));
             }
         }
-
+        else if (ERTS_IS_ATOM_STR("mbuf", BIF_ARG_1)) {
+            Uint sz = size_object(BIF_ARG_2);
+            ErlHeapFragment* frag = new_message_buffer(sz);
+            Eterm *hp = frag->mem;
+            Eterm copy = copy_struct(BIF_ARG_2, sz, &hp, &frag->off_heap);
+            frag->next = BIF_P->mbuf;
+            BIF_P->mbuf = frag;
+            BIF_P->mbuf_sz += sz;
+            BIF_RET(copy);
+        }
     }
 
     BIF_ERROR(BIF_P, BADARG);
diff --git a/erts/emulator/beam/erl_db_hash.c b/erts/emulator/beam/erl_db_hash.c
index cf928a9035..47d304f860 100644
--- a/erts/emulator/beam/erl_db_hash.c
+++ b/erts/emulator/beam/erl_db_hash.c
@@ -1328,11 +1328,7 @@ static int match_traverse(Process* p, DbTableHash* tb,
                 unlock_hash_function(lck);
                 break;
             }
-            if (iterations_left <= 0 || MBUF(p)) {
-                /*
-                 * We have either reached our limit, or just created some heap fragments.
-                 * Since many heap fragments will make the GC slower, trap and GC now.
-                 */
+            if (iterations_left <= 0) {
                 unlock_hash_function(lck);
                 ret_value = on_trap(context_ptr, slot_ix, got, &mpi.mp, ret);
                 goto done;
@@ -1451,11 +1447,7 @@ static int match_traverse_continue(Process* p, DbTableHash* tb,
                 unlock_hash_function(lck);
                 break;
             }
-            if (iterations_left <= 0 || MBUF(p)) {
-                /*
-                 * We have either reached our limit, or just created some heap fragments.
-                 * Since many heap fragments will make the GC slower, trap and GC now.
-                 */
+            if (iterations_left <= 0) {
                 unlock_hash_function(lck);
                 ret_value = on_trap(context_ptr, slot_ix, got, mpp, ret);
                 goto done;
diff --git a/erts/emulator/beam/erl_db_tree.c b/erts/emulator/beam/erl_db_tree.c
index 7c80e92e50..f222ac45ae 100644
--- a/erts/emulator/beam/erl_db_tree.c
+++ b/erts/emulator/beam/erl_db_tree.c
@@ -3344,13 +3344,6 @@ static int doit_select(DbTableTree *tb, TreeDbTerm *this, void *ptr,
     if (is_value(ret)) {
 	sc->accum = CONS(hp, ret, sc->accum);
     }
-    if (MBUF(sc->p)) {
-	/*
-	 * Force a trap and GC if a heap fragment was created. Many heap fragments
-	 * make the GC slow.
-	 */
-	sc->max = 0;
-    }
     if (--(sc->max) <= 0) {
 	return 0;
     }
@@ -3407,13 +3400,6 @@ static int doit_select_chunk(DbTableTree *tb, TreeDbTerm *this, void *ptr,
 	++(sc->got);
 	sc->accum = CONS(hp, ret, sc->accum);
     }
-    if (MBUF(sc->p)) {
-	/*
-	 * Force a trap and GC if a heap fragment was created. Many heap fragments
-	 * make the GC slow.
-	 */
-	sc->max = 0;
-    }
     if (--(sc->max) <= 0 || sc->got == sc->chunk_size) {
 	return 0;
     }