Merge branch 'bjorn/erts/persistent_terms/OTP-14669' into maint

* bjorn/erts/persistent_terms/OTP-14669:
  Implement a tab for persistent terms in crashdump viewer
  Add tests of persistent terms for crashdump_viewer
  Add a persistent term storage
  Refactor releasing of literals
  Extend the sharing-preserving routines to optionally copy literals

13 files changed, 1727 insertions, 44 deletions

diff --git a/erts/emulator/Makefile.in b/erts/emulator/Makefile.in
index 054692819e..d5ceb4b00b 100644
--- a/erts/emulator/Makefile.in
+++ b/erts/emulator/Makefile.in
@@ -633,21 +633,22 @@ GENERATE += $(TTF_DIR)/driver_tab.c
 # This list must be consistent with PRE_LOADED_MODULES in
 # erts/preloaded/src/Makefile.
 
-PRELOAD_BEAM =		$(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erts_code_purger.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/init.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/prim_buffer.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/prim_eval.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/prim_inet.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/prim_file.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/zlib.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/prim_zip.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erl_prim_loader.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erlang.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erts_internal.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erl_tracer.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erts_literal_area_collector.beam \
-			$(ERL_TOP)/erts/preloaded/ebin/erts_dirty_process_signal_handler.beam
+PRELOAD_BEAM =	$(ERL_TOP)/erts/preloaded/ebin/otp_ring0.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erts_code_purger.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/init.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/prim_buffer.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/prim_eval.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/prim_inet.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/prim_file.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/zlib.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/prim_zip.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erl_prim_loader.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erlang.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erts_internal.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erl_tracer.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erts_literal_area_collector.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/erts_dirty_process_signal_handler.beam \
+		$(ERL_TOP)/erts/preloaded/ebin/persistent_term.beam
 
 ifeq ($(TARGET),win32)
 # On windows the preloaded objects are in a resource object.
@@ -839,6 +840,7 @@ RUN_OBJS += \
 	$(OBJDIR)/erl_bif_ddll.o  	$(OBJDIR)/erl_bif_guard.o \
 	$(OBJDIR)/erl_bif_info.o	$(OBJDIR)/erl_bif_op.o \
 	$(OBJDIR)/erl_bif_os.o		$(OBJDIR)/erl_bif_lists.o \
+	$(OBJDIR)/erl_bif_persistent.o \
 	$(OBJDIR)/erl_bif_trace.o	$(OBJDIR)/erl_bif_unique.o \
 	$(OBJDIR)/erl_bif_wrap.o	$(OBJDIR)/erl_nfunc_sched.o \
 	$(OBJDIR)/erl_guard_bifs.o 	$(OBJDIR)/erl_dirty_bif_wrap.o \
diff --git a/erts/emulator/beam/atom.names b/erts/emulator/beam/atom.names
index 45b7540aeb..82bb620d62 100644
--- a/erts/emulator/beam/atom.names
+++ b/erts/emulator/beam/atom.names
@@ -182,6 +182,7 @@ atom control
 atom copy
 atom copy_literals
 atom counters
+atom count
 atom cpu
 atom cpu_timestamp
 atom cr
@@ -287,6 +288,7 @@ atom gc_minor_end
 atom gc_minor_start
 atom Ge='>='
 atom generational
+atom get_all_trap
 atom get_seq_token
 atom get_tcw
 atom gather_gc_info_result
@@ -325,6 +327,7 @@ atom index
 atom infinity
 atom info
 atom info_msg
+atom info_trap
 atom init
 atom initial_call
 atom input
diff --git a/erts/emulator/beam/beam_bif_load.c b/erts/emulator/beam/beam_bif_load.c
index d221e6aea6..bb1b2e5b27 100644
--- a/erts/emulator/beam/beam_bif_load.c
+++ b/erts/emulator/beam/beam_bif_load.c
@@ -1752,29 +1752,7 @@ BIF_RETTYPE erts_internal_purge_module_2(BIF_ALIST_2)
 	finalize_purge_operation(BIF_P, ret == am_true);
 
 	if (literals) {
-	    ErtsLiteralAreaRef *ref;
-            ErtsMessage *mp;
-	    ref = erts_alloc(ERTS_ALC_T_LITERAL_REF,
-			     sizeof(ErtsLiteralAreaRef));
-	    ref->literal_area = literals;
-	    ref->next = NULL;
-	    erts_mtx_lock(&release_literal_areas.mtx);
-	    if (release_literal_areas.last) {
-		release_literal_areas.last->next = ref;
-		release_literal_areas.last = ref;
-	    }
-	    else {
-		release_literal_areas.first = ref;
-		release_literal_areas.last = ref;
-	    }
-	    erts_mtx_unlock(&release_literal_areas.mtx);
-            mp = erts_alloc_message(0, NULL);
-            ERL_MESSAGE_TOKEN(mp) = am_undefined;
-	    erts_queue_proc_message(BIF_P,
-                               erts_literal_area_collector,
-			       0,
-			       mp,
-			       am_copy_literals);
+            erts_queue_release_literals(BIF_P, literals);
 	}
 
 	return ret;
@@ -1786,6 +1764,41 @@ BIF_RETTYPE erts_internal_purge_module_2(BIF_ALIST_2)
     }
 }
 
+void
+erts_queue_release_literals(Process* c_p, ErtsLiteralArea* literals)
+{
+    ErtsLiteralAreaRef *ref;
+    ErtsMessage *mp;
+    ref = erts_alloc(ERTS_ALC_T_LITERAL_REF,
+                     sizeof(ErtsLiteralAreaRef));
+    ref->literal_area = literals;
+    ref->next = NULL;
+    erts_mtx_lock(&release_literal_areas.mtx);
+    if (release_literal_areas.last) {
+        release_literal_areas.last->next = ref;
+        release_literal_areas.last = ref;
+    } else {
+        release_literal_areas.first = ref;
+        release_literal_areas.last = ref;
+    }
+    erts_mtx_unlock(&release_literal_areas.mtx);
+    mp = erts_alloc_message(0, NULL);
+    ERL_MESSAGE_TOKEN(mp) = am_undefined;
+    if (c_p == NULL) {
+        erts_queue_message(erts_literal_area_collector,
+                           0,
+                           mp,
+                           am_copy_literals,
+                           am_system);
+    } else {
+        erts_queue_proc_message(c_p,
+                                erts_literal_area_collector,
+                                0,
+                                mp,
+                                am_copy_literals);
+    }
+}
+
 /*
  * Move code from current to old and null all export entries for the module
  */
diff --git a/erts/emulator/beam/bif.tab b/erts/emulator/beam/bif.tab
index 7548924178..f1f34ae323 100644
--- a/erts/emulator/beam/bif.tab
+++ b/erts/emulator/beam/bif.tab
@@ -40,6 +40,7 @@
 # Note: Guards BIFs usually require special support in the compiler.
 #
 
+
 gcbif erlang:abs/1
 bif erlang:adler32/1
 bif erlang:adler32/2
@@ -698,3 +699,14 @@ ubif erlang:map_get/2
 ubif erlang:is_map_key/2
 bif ets:internal_delete_all/2
 bif ets:internal_select_delete/2
+
+#
+# New in 21.2
+#
+
+bif persistent_term:put/2
+bif persistent_term:get/1
+bif persistent_term:get/0
+bif persistent_term:erase/1
+bif persistent_term:info/0
+bif erts_internal:erase_persistent_terms/0
diff --git a/erts/emulator/beam/copy.c b/erts/emulator/beam/copy.c
index e7bfd04b73..e7bd046e18 100644
--- a/erts/emulator/beam/copy.c
+++ b/erts/emulator/beam/copy.c
@@ -1074,6 +1074,7 @@ Uint copy_shared_calculate(Eterm obj, erts_shcopy_t *info)
     Eterm* ptr;
     Eterm *lit_purge_ptr = info->lit_purge_ptr;
     Uint lit_purge_sz = info->lit_purge_sz;
+    int copy_literals = info->copy_literals;
 #ifdef DEBUG
     Eterm mypid = erts_get_current_pid();
 #endif
@@ -1119,7 +1120,7 @@ Uint copy_shared_calculate(Eterm obj, erts_shcopy_t *info)
 	    /* off heap list pointers are copied verbatim */
 	    if (erts_is_literal(obj,ptr)) {
 		VERBOSE(DEBUG_SHCOPY, ("[pid=%T] bypassed copying %p is %T\n", mypid, ptr, obj));
-                if (in_literal_purge_area(ptr))
+                if (copy_literals || in_literal_purge_area(ptr))
                     info->literal_size += size_object(obj);
 		goto pop_next;
 	    }
@@ -1170,7 +1171,7 @@ Uint copy_shared_calculate(Eterm obj, erts_shcopy_t *info)
 	    /* off heap pointers to boxes are copied verbatim */
 	    if (erts_is_literal(obj,ptr)) {
 		VERBOSE(DEBUG_SHCOPY, ("[pid=%T] bypassed copying %p is %T\n", mypid, ptr, obj));
-                if (in_literal_purge_area(ptr))
+                if (copy_literals || in_literal_purge_area(ptr))
                     info->literal_size += size_object(obj);
 		goto pop_next;
 	    }
@@ -1338,6 +1339,7 @@ Uint copy_shared_perform(Eterm obj, Uint size, erts_shcopy_t *info,
     unsigned remaining;
     Eterm *lit_purge_ptr = info->lit_purge_ptr;
     Uint lit_purge_sz = info->lit_purge_sz;
+    int copy_literals = info->copy_literals;
 #ifdef DEBUG
     Eterm mypid = erts_get_current_pid();
     Eterm saved_obj = obj;
@@ -1387,7 +1389,7 @@ Uint copy_shared_perform(Eterm obj, Uint size, erts_shcopy_t *info,
 	    ptr = list_val(obj);
 	    /* off heap list pointers are copied verbatim */
 	    if (erts_is_literal(obj,ptr)) {
-                if (!in_literal_purge_area(ptr)) {
+                if (!(copy_literals || in_literal_purge_area(ptr))) {
                     *resp = obj;
                 } else {
                     Uint bsz = 0;
@@ -1455,7 +1457,7 @@ Uint copy_shared_perform(Eterm obj, Uint size, erts_shcopy_t *info,
 	    ptr = boxed_val(obj);
 	    /* off heap pointers to boxes are copied verbatim */
 	    if (erts_is_literal(obj,ptr)) {
-                if (!in_literal_purge_area(ptr)) {
+                if (!(copy_literals || in_literal_purge_area(ptr))) {
                     *resp = obj;
                 } else {
                     Uint bsz = 0;
diff --git a/erts/emulator/beam/erl_alloc.types b/erts/emulator/beam/erl_alloc.types
index 98ba0e5f07..3fc036a13c 100644
--- a/erts/emulator/beam/erl_alloc.types
+++ b/erts/emulator/beam/erl_alloc.types
@@ -278,6 +278,9 @@ type    LIST_TRAP       SHORT_LIVED     PROCESSES       list_bif_trap_state
 
 type	ENVIRONMENT	SYSTEM		SYSTEM		environment
 
+type	PERSISTENT_TERM	LONG_LIVED	CODE		persisten_term
+type	PERSISTENT_LOCK_Q SHORT_LIVED	SYSTEM		persistent_lock_q
+
 #
 # Types used for special emulators
 #
diff --git a/erts/emulator/beam/erl_bif_persistent.c b/erts/emulator/beam/erl_bif_persistent.c
new file mode 100644
index 0000000000..9dca768a18
--- /dev/null
+++ b/erts/emulator/beam/erl_bif_persistent.c
@@ -0,0 +1,983 @@
+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2018. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+/*
+ * Purpose: Implement persistent term storage.
+ */
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+#include "sys.h"
+#include "erl_vm.h"
+#include "global.h"
+#include "erl_process.h"
+#include "error.h"
+#include "erl_driver.h"
+#include "bif.h"
+#include "erl_map.h"
+#include "erl_binary.h"
+
+/*
+ * The limit for the number of persistent terms before
+ * a warning is issued.
+ */
+
+#define WARNING_LIMIT 20000
+#define XSTR(s) STR(s)
+#define STR(s) #s
+
+/*
+ * Parameters for the hash table.
+ */
+#define INITIAL_SIZE 8
+#define LOAD_FACTOR ((Uint)50)
+#define MUST_GROW(t) (((Uint)100) * t->num_entries >= LOAD_FACTOR * t->allocated)
+#define MUST_SHRINK(t) (((Uint)200) * t->num_entries <= LOAD_FACTOR * t->allocated && \
+                        t->allocated > INITIAL_SIZE)
+
+typedef struct hash_table {
+    Uint allocated;
+    Uint num_entries;
+    Uint mask;
+    Uint first_to_delete;
+    Uint num_to_delete;
+    erts_atomic_t refc;
+    struct hash_table* delete_next;
+    ErtsThrPrgrLaterOp thr_prog_op;
+    Eterm term[1];
+} HashTable;
+
+typedef struct trap_data {
+    HashTable* table;
+    Uint idx;
+    Uint remaining;
+    Uint memory;    /* Used by info/0 to count used memory */
+} TrapData;
+
+/*
+ * Declarations of local functions.
+ */
+
+static HashTable* create_initial_table(void);
+static Uint lookup(HashTable* hash_table, Eterm key);
+static HashTable* copy_table(HashTable* old_table, Uint new_size, int rehash);
+static HashTable* tmp_table_copy(HashTable* old_table);
+static int try_seize_update_permission(Process* c_p);
+static void release_update_permission(int release_updater);
+static void table_updater(void* table);
+static void table_deleter(void* hash_table);
+static void dec_table_refc(Process* c_p, HashTable* old_table);
+static void delete_table(Process* c_p, HashTable* table);
+static void mark_for_deletion(HashTable* hash_table, Uint entry_index);
+static ErtsLiteralArea* term_to_area(Eterm tuple);
+static void suspend_updater(Process* c_p);
+static Eterm do_get_all(Process* c_p, TrapData* trap_data, Eterm res);
+static Eterm do_info(Process* c_p, TrapData* trap_data);
+static void append_to_delete_queue(HashTable* table);
+static HashTable* next_to_delete(void);
+static Eterm alloc_trap_data(Process* c_p);
+static int cleanup_trap_data(Binary *bp);
+
+/*
+ * Traps
+ */
+
+static Export persistent_term_get_all_export;
+static BIF_RETTYPE persistent_term_get_all_trap(BIF_ALIST_2);
+static Export persistent_term_info_export;
+static BIF_RETTYPE persistent_term_info_trap(BIF_ALIST_1);
+
+/*
+ * Pointer to the current hash table.
+ */
+
+static erts_atomic_t the_hash_table;
+
+/*
+ * Queue of processes waiting to update the hash table.
+ */
+
+struct update_queue_item {
+    Process *p;
+    struct update_queue_item* next;
+};
+
+static erts_mtx_t update_table_permission_mtx;
+static struct update_queue_item* update_queue = NULL;
+static Process* updater_process = NULL;
+
+/* Protected by update_table_permission_mtx */
+static ErtsThrPrgrLaterOp thr_prog_op;
+static int issued_warning = 0;
+
+/*
+ * Queue of hash tables to be deleted.
+ */
+
+static erts_mtx_t delete_queue_mtx;
+static HashTable* delete_queue_head = NULL;
+static HashTable** delete_queue_tail = &delete_queue_head;
+
+/*
+ * The following variables are only used during crash dumping. They
+ * are intialized by erts_init_persistent_dumping().
+ */
+
+ErtsLiteralArea** erts_persistent_areas;
+Uint erts_num_persistent_areas;
+
+void erts_init_bif_persistent_term(void)
+{
+    HashTable* hash_table;
+
+    /*
+     * Initialize the mutex protecting updates.
+     */
+
+    erts_mtx_init(&update_table_permission_mtx,
+                  "update_persistent_term_permission",
+                  NIL,
+                  ERTS_LOCK_FLAGS_PROPERTY_STATIC |
+                  ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
+
+    /*
+     * Initialize delete queue.
+     */
+
+    erts_mtx_init(&delete_queue_mtx,
+                  "persistent_term_delete_permission",
+                  NIL,
+                  ERTS_LOCK_FLAGS_PROPERTY_STATIC |
+                  ERTS_LOCK_FLAGS_CATEGORY_GENERIC);
+
+    /*
+     * Allocate a small initial hash table.
+     */
+
+    hash_table = create_initial_table();
+    erts_atomic_init_nob(&the_hash_table, (erts_aint_t)hash_table);
+
+    /*
+     * Initialize export entry for traps
+     */
+
+    erts_init_trap_export(&persistent_term_get_all_export,
+			  am_persistent_term, am_get_all_trap, 2,
+			  &persistent_term_get_all_trap);
+    erts_init_trap_export(&persistent_term_info_export,
+			  am_persistent_term, am_info_trap, 1,
+			  &persistent_term_info_trap);
+}
+
+BIF_RETTYPE persistent_term_put_2(BIF_ALIST_2)
+{
+    Eterm key;
+    Eterm term;
+    Eterm heap[3];
+    Eterm tuple;
+    HashTable* hash_table;
+    Uint term_size;
+    Uint lit_area_size;
+    ErlOffHeap code_off_heap;
+    ErtsLiteralArea* literal_area;
+    erts_shcopy_t info;
+    Eterm* ptr;
+    Uint entry_index;
+
+    if (!try_seize_update_permission(BIF_P)) {
+	ERTS_BIF_YIELD2(bif_export[BIF_persistent_term_put_2],
+                        BIF_P, BIF_ARG_1, BIF_ARG_2);
+    }
+
+    hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+
+    key = BIF_ARG_1;
+    term = BIF_ARG_2;
+
+    entry_index = lookup(hash_table, key);
+
+    heap[0] = make_arityval(2);
+    heap[1] = key;
+    heap[2] = term;
+    tuple = make_tuple(heap);
+
+    if (is_nil(hash_table->term[entry_index])) {
+        Uint size = hash_table->allocated;
+        if (MUST_GROW(hash_table)) {
+            size *= 2;
+        }
+        hash_table = copy_table(hash_table, size, 0);
+        entry_index = lookup(hash_table, key);
+        hash_table->num_entries++;
+    } else {
+        Eterm tuple = hash_table->term[entry_index];
+        Eterm old_term;
+
+        ASSERT(is_tuple_arity(tuple, 2));
+        old_term = boxed_val(tuple)[2];
+        if (EQ(term, old_term)) {
+            /* Same value. No need to update anything. */
+            release_update_permission(0);
+            BIF_RET(am_ok);
+        } else {
+            /* Mark the old term for deletion. */
+            mark_for_deletion(hash_table, entry_index);
+            hash_table = copy_table(hash_table, hash_table->allocated, 0);
+        }
+    }
+
+    /*
+     * Preserve internal sharing in the term by using the
+     * sharing-preserving functions. However, literals must
+     * be copied in case the module holding them are unloaded.
+     */
+    INITIALIZE_SHCOPY(info);
+    info.copy_literals = 1;
+    term_size = copy_shared_calculate(tuple, &info);
+    ERTS_INIT_OFF_HEAP(&code_off_heap);
+    lit_area_size = ERTS_LITERAL_AREA_ALLOC_SIZE(term_size);
+    literal_area = erts_alloc(ERTS_ALC_T_LITERAL, lit_area_size);
+    ptr = &literal_area->start[0];
+    literal_area->end = ptr + term_size;
+    tuple = copy_shared_perform(tuple, term_size, &info, &ptr, &code_off_heap);
+    ASSERT(tuple_val(tuple) == literal_area->start);
+    literal_area->off_heap = code_off_heap.first;
+    DESTROY_SHCOPY(info);
+    erts_set_literal_tag(&tuple, literal_area->start, term_size);
+    hash_table->term[entry_index] = tuple;
+
+    erts_schedule_thr_prgr_later_op(table_updater, hash_table, &thr_prog_op);
+    suspend_updater(BIF_P);
+
+    /*
+     * Issue a warning once if the warning limit has been exceeded.
+     */
+
+    if (hash_table->num_entries > WARNING_LIMIT && issued_warning == 0) {
+        static char w[] =
+            "More than " XSTR(WARNING_LIMIT) " persistent terms "
+            "have been created.\n"
+            "It is recommended to avoid creating an excessive number of\n"
+            "persistent terms, as creation and deletion of persistent terms\n"
+            "will be slower as the number of persistent terms increases.\n";
+        issued_warning = 1;
+	erts_send_warning_to_logger_str(BIF_P->group_leader, w);
+    }
+
+    ERTS_BIF_YIELD_RETURN(BIF_P, am_ok);
+}
+
+BIF_RETTYPE persistent_term_get_0(BIF_ALIST_0)
+{
+    HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    TrapData* trap_data;
+    Eterm res = NIL;
+    Eterm magic_ref;
+    Binary* mbp;
+
+    magic_ref = alloc_trap_data(BIF_P);
+    mbp = erts_magic_ref2bin(magic_ref);
+    trap_data = ERTS_MAGIC_BIN_DATA(mbp);
+    trap_data->table = hash_table;
+    trap_data->idx = 0;
+    trap_data->remaining = hash_table->num_entries;
+    res = do_get_all(BIF_P, trap_data, res);
+    if (trap_data->remaining == 0) {
+        BUMP_REDS(BIF_P, hash_table->num_entries);
+        trap_data->table = NULL; /* Prevent refc decrement */
+        BIF_RET(res);
+    } else {
+        /*
+         * Increment the ref counter to prevent an update operation (by put/2
+         * or erase/1) to delete this hash table.
+         */
+        erts_atomic_inc_nob(&hash_table->refc);
+        BUMP_ALL_REDS(BIF_P);
+        BIF_TRAP2(&persistent_term_get_all_export, BIF_P, magic_ref, res);
+    }
+}
+
+BIF_RETTYPE persistent_term_get_1(BIF_ALIST_1)
+{
+    Eterm key = BIF_ARG_1;
+    HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    Uint entry_index;
+    Eterm term;
+
+    entry_index = lookup(hash_table, key);
+    term = hash_table->term[entry_index];
+    if (is_boxed(term)) {
+        ASSERT(is_tuple_arity(term, 2));
+        BIF_RET(tuple_val(term)[2]);
+    }
+    BIF_ERROR(BIF_P, BADARG);
+}
+
+BIF_RETTYPE persistent_term_erase_1(BIF_ALIST_1)
+{
+    Eterm key = BIF_ARG_1;
+    HashTable* old_table;
+    HashTable* new_table;
+    Uint entry_index;
+    Eterm old_term;
+
+    if (!try_seize_update_permission(BIF_P)) {
+	ERTS_BIF_YIELD1(bif_export[BIF_persistent_term_erase_1],
+                        BIF_P, BIF_ARG_1);
+    }
+
+    old_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    entry_index = lookup(old_table, key);
+    old_term = old_table->term[entry_index];
+    if (is_boxed(old_term)) {
+        Uint new_size;
+        HashTable* tmp_table;
+
+        /*
+         * Since we don't use any delete markers, we must rehash
+         * the table when deleting terms to ensure that all terms
+         * can still be reached if there are hash collisions.
+         * We can't rehash in place and it would not be safe to modify
+         * the old table yet, so we will first need a new
+         * temporary table copy of the same size as the old one.
+         */
+
+        ASSERT(is_tuple_arity(old_term, 2));
+        tmp_table = tmp_table_copy(old_table);
+
+        /*
+         * Delete the term from the temporary table. Then copy the
+         * temporary table to a new table, rehashing the entries
+         * while copying.
+         */
+
+        tmp_table->term[entry_index] = NIL;
+        tmp_table->num_entries--;
+        new_size = tmp_table->allocated;
+        if (MUST_SHRINK(tmp_table)) {
+            new_size /= 2;
+        }
+        new_table = copy_table(tmp_table, new_size, 1);
+        erts_free(ERTS_ALC_T_TMP, tmp_table);
+
+        mark_for_deletion(old_table, entry_index);
+        erts_schedule_thr_prgr_later_op(table_updater, new_table, &thr_prog_op);
+        suspend_updater(BIF_P);
+        ERTS_BIF_YIELD_RETURN(BIF_P, am_true);
+    }
+
+    /*
+     * Key is not present. Nothing to do.
+     */
+
+    ASSERT(is_nil(old_term));
+    release_update_permission(0);
+    BIF_RET(am_false);
+}
+
+BIF_RETTYPE erts_internal_erase_persistent_terms_0(BIF_ALIST_0)
+{
+    HashTable* old_table;
+    HashTable* new_table;
+
+    if (!try_seize_update_permission(BIF_P)) {
+	ERTS_BIF_YIELD0(bif_export[BIF_erts_internal_erase_persistent_terms_0],
+                        BIF_P);
+    }
+    old_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    old_table->first_to_delete = 0;
+    old_table->num_to_delete = old_table->allocated;
+    new_table = create_initial_table();
+    erts_schedule_thr_prgr_later_op(table_updater, new_table, &thr_prog_op);
+    suspend_updater(BIF_P);
+    ERTS_BIF_YIELD_RETURN(BIF_P, am_true);
+}
+
+BIF_RETTYPE persistent_term_info_0(BIF_ALIST_0)
+{
+    HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    TrapData* trap_data;
+    Eterm res = NIL;
+    Eterm magic_ref;
+    Binary* mbp;
+
+    magic_ref = alloc_trap_data(BIF_P);
+    mbp = erts_magic_ref2bin(magic_ref);
+    trap_data = ERTS_MAGIC_BIN_DATA(mbp);
+    trap_data->table = hash_table;
+    trap_data->idx = 0;
+    trap_data->remaining = hash_table->num_entries;
+    trap_data->memory = 0;
+    res = do_info(BIF_P, trap_data);
+    if (trap_data->remaining == 0) {
+        BUMP_REDS(BIF_P, hash_table->num_entries);
+        trap_data->table = NULL; /* Prevent refc decrement */
+        BIF_RET(res);
+    } else {
+        /*
+         * Increment the ref counter to prevent an update operation (by put/2
+         * or erase/1) to delete this hash table.
+         */
+        erts_atomic_inc_nob(&hash_table->refc);
+        BUMP_ALL_REDS(BIF_P);
+        BIF_TRAP2(&persistent_term_info_export, BIF_P, magic_ref, res);
+    }
+}
+
+Uint
+erts_persistent_term_count(void)
+{
+    HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    return hash_table->num_entries;
+}
+
+void
+erts_init_persistent_dumping(void)
+{
+    HashTable* hash_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    ErtsLiteralArea** area_p;
+    Uint i;
+
+    /*
+     * Overwrite the array of Eterms in the current hash table
+     * with pointers to literal areas.
+     */
+
+    erts_persistent_areas = (ErtsLiteralArea **) hash_table->term;
+    erts_num_persistent_areas = hash_table->num_entries;
+    area_p = erts_persistent_areas;
+    for (i = 0; i < hash_table->allocated; i++) {
+        Eterm term = hash_table->term[i];
+
+        if (is_boxed(term)) {
+            *area_p++ = term_to_area(term);
+        }
+    }
+}
+
+/*
+ * Local functions.
+ */
+
+static HashTable*
+create_initial_table(void)
+{
+    HashTable* hash_table;
+    int i;
+
+    hash_table = (HashTable *) erts_alloc(ERTS_ALC_T_PERSISTENT_TERM,
+                                          sizeof(HashTable)+sizeof(Eterm) *
+                                          (INITIAL_SIZE-1));
+    hash_table->allocated = INITIAL_SIZE;
+    hash_table->num_entries = 0;
+    hash_table->mask = INITIAL_SIZE-1;
+    hash_table->first_to_delete = 0;
+    hash_table->num_to_delete = 0;
+    erts_atomic_init_nob(&hash_table->refc, (erts_aint_t)1);
+    for (i = 0; i < INITIAL_SIZE; i++) {
+        hash_table->term[i] = NIL;
+    }
+    return hash_table;
+}
+
+static BIF_RETTYPE
+persistent_term_get_all_trap(BIF_ALIST_2)
+{
+    TrapData* trap_data;
+    Eterm res = BIF_ARG_2;
+    Uint bump_reds;
+    Binary* mbp;
+
+    ASSERT(is_list(BIF_ARG_2));
+    mbp = erts_magic_ref2bin(BIF_ARG_1);
+    trap_data = ERTS_MAGIC_BIN_DATA(mbp);
+    bump_reds = trap_data->remaining;
+    res = do_get_all(BIF_P, trap_data, res);
+    ASSERT(is_list(res));
+    if (trap_data->remaining > 0) {
+        BUMP_ALL_REDS(BIF_P);
+        BIF_TRAP2(&persistent_term_get_all_export, BIF_P, BIF_ARG_1, res);
+    } else {
+        /*
+         * Decrement ref count (and possibly delete the hash table
+         * and associated literal area).
+         */
+        dec_table_refc(BIF_P, trap_data->table);
+        trap_data->table = NULL; /* Prevent refc decrement */
+        BUMP_REDS(BIF_P, bump_reds);
+        BIF_RET(res);
+    }
+}
+
+static Eterm
+do_get_all(Process* c_p, TrapData* trap_data, Eterm res)
+{
+    HashTable* hash_table;
+    Uint remaining;
+    Uint idx;
+    Uint max_iter;
+    Uint i;
+    Eterm* hp;
+    Uint heap_size;
+    struct copy_term {
+        Uint key_size;
+        Eterm* tuple_ptr;
+    } *copy_data;
+
+    hash_table = trap_data->table;
+    idx = trap_data->idx;
+#if defined(DEBUG) || defined(VALGRIND)
+    max_iter = 50;
+#else
+    max_iter = ERTS_BIF_REDS_LEFT(c_p);
+#endif
+    remaining = trap_data->remaining < max_iter ?
+        trap_data->remaining : max_iter;
+    trap_data->remaining -= remaining;
+
+    copy_data = (struct copy_term *) erts_alloc(ERTS_ALC_T_TMP,
+                                                remaining *
+                                                sizeof(struct copy_term));
+    i = 0;
+    heap_size = (2 + 3) * remaining;
+    while (remaining != 0) {
+        Eterm term = hash_table->term[idx];
+        if (is_tuple(term)) {
+            Uint key_size;
+            Eterm* tup_val;
+
+            ASSERT(is_tuple_arity(term, 2));
+            tup_val = tuple_val(term);
+            key_size = size_object(tup_val[1]);
+            copy_data[i].key_size = key_size;
+            copy_data[i].tuple_ptr = tup_val;
+            heap_size += key_size;
+            i++;
+            remaining--;
+        }
+        idx++;
+    }
+    trap_data->idx = idx;
+
+    hp = HAlloc(c_p, heap_size);
+    remaining = i;
+    for (i = 0; i < remaining; i++) {
+        Eterm* tuple_ptr;
+        Uint key_size;
+        Eterm key;
+        Eterm tup;
+
+        tuple_ptr = copy_data[i].tuple_ptr;
+        key_size = copy_data[i].key_size;
+        key = copy_struct(tuple_ptr[1], key_size, &hp, &c_p->off_heap);
+        tup = TUPLE2(hp, key, tuple_ptr[2]);
+        hp += 3;
+        res = CONS(hp, tup, res);
+        hp += 2;
+    }
+    erts_free(ERTS_ALC_T_TMP, copy_data);
+    return res;
+}
+
+static BIF_RETTYPE
+persistent_term_info_trap(BIF_ALIST_1)
+{
+    TrapData* trap_data = (TrapData *) BIF_ARG_1;
+    Eterm res;
+    Uint bump_reds;
+    Binary* mbp;
+
+    mbp = erts_magic_ref2bin(BIF_ARG_1);
+    trap_data = ERTS_MAGIC_BIN_DATA(mbp);
+    bump_reds = trap_data->remaining;
+    res = do_info(BIF_P, trap_data);
+    if (trap_data->remaining > 0) {
+        ASSERT(res == am_ok);
+        BUMP_ALL_REDS(BIF_P);
+        BIF_TRAP1(&persistent_term_info_export, BIF_P, BIF_ARG_1);
+    } else {
+        /*
+         * Decrement ref count (and possibly delete the hash table
+         * and associated literal area).
+         */
+        dec_table_refc(BIF_P, trap_data->table);
+        trap_data->table = NULL; /* Prevent refc decrement */
+        BUMP_REDS(BIF_P, bump_reds);
+        ASSERT(is_map(res));
+        BIF_RET(res);
+    }
+}
+
+#define DECL_AM(S) Eterm AM_ ## S = am_atom_put(#S, sizeof(#S) - 1)
+
+static Eterm
+do_info(Process* c_p, TrapData* trap_data)
+{
+    HashTable* hash_table;
+    Uint remaining;
+    Uint idx;
+    Uint max_iter;
+
+    hash_table = trap_data->table;
+    idx = trap_data->idx;
+#if defined(DEBUG) || defined(VALGRIND)
+    max_iter = 50;
+#else
+    max_iter = ERTS_BIF_REDS_LEFT(c_p);
+#endif
+    remaining = trap_data->remaining < max_iter ? trap_data->remaining : max_iter;
+    trap_data->remaining -= remaining;
+    while (remaining != 0) {
+        if (is_boxed(hash_table->term[idx])) {
+            ErtsLiteralArea* area;
+            area = term_to_area(hash_table->term[idx]);
+            trap_data->memory += sizeof(ErtsLiteralArea) +
+                sizeof(Eterm) * (area->end - area->start - 1);
+            remaining--;
+        }
+        idx++;
+    }
+    trap_data->idx = idx;
+    if (trap_data->remaining > 0) {
+        return am_ok;           /* Dummy return value */
+    } else {
+        Eterm* hp;
+        Eterm count_term;
+        Eterm memory_term;
+        Eterm res;
+        Uint memory;
+        Uint hsz = MAP_SZ(2);
+
+        memory = sizeof(HashTable) + (trap_data->table->allocated-1) *
+            sizeof(Eterm) + trap_data->memory;
+        (void) erts_bld_uint(NULL, &hsz, hash_table->num_entries);
+        (void) erts_bld_uint(NULL, &hsz, memory);
+        hp = HAlloc(c_p, hsz);
+	count_term = erts_bld_uint(&hp, NULL, hash_table->num_entries);
+	memory_term = erts_bld_uint(&hp, NULL, memory);
+        res = MAP2(hp, am_count, count_term, am_memory, memory_term);
+        return res;
+    }
+}
+
+#undef DECL_AM
+
+static Eterm
+alloc_trap_data(Process* c_p)
+{
+    Binary* mbp = erts_create_magic_binary(sizeof(TrapData),
+                                           cleanup_trap_data);
+    Eterm* hp;
+
+    hp = HAlloc(c_p, ERTS_MAGIC_REF_THING_SIZE);
+    return erts_mk_magic_ref(&hp, &MSO(c_p), mbp);
+}
+
+static int
+cleanup_trap_data(Binary *bp)
+{
+    TrapData* trap_data = ERTS_MAGIC_BIN_DATA(bp);
+
+    if (trap_data->table) {
+        /*
+         * The process has been killed and is now exiting.
+         * Decrement the reference counter for the table.
+         */
+        dec_table_refc(NULL, trap_data->table);
+    }
+    return 1;
+}
+
+static Uint
+lookup(HashTable* hash_table, Eterm key)
+{
+    Uint mask = hash_table->mask;
+    Eterm* table = hash_table->term;
+    Uint32 idx = make_internal_hash(key, 0);
+    Eterm term;
+
+    do {
+        idx++;
+        term = table[idx & mask];
+    } while (is_boxed(term) && !EQ(key, (tuple_val(term))[1]));
+    return idx & mask;
+}
+
+static HashTable*
+tmp_table_copy(HashTable* old_table)
+{
+    Uint size = old_table->allocated;
+    HashTable* tmp_table;
+    Uint i;
+
+    tmp_table = (HashTable *) erts_alloc(ERTS_ALC_T_TMP,
+                                         sizeof(HashTable) +
+                                         sizeof(Eterm) * (size-1));
+    *tmp_table = *old_table;
+    for (i = 0; i < size; i++) {
+        tmp_table->term[i] = old_table->term[i];
+    }
+    return tmp_table;
+}
+
+static HashTable*
+copy_table(HashTable* old_table, Uint new_size, int rehash)
+{
+    HashTable* new_table;
+    Uint old_size = old_table->allocated;
+    Uint i;
+
+    new_table = (HashTable *) erts_alloc(ERTS_ALC_T_PERSISTENT_TERM,
+                                         sizeof(HashTable) +
+                                         sizeof(Eterm) * (new_size-1));
+    if (old_table->allocated == new_size && !rehash) {
+        /*
+         * Same size and no key deleted. Make an exact copy of the table.
+         */
+        *new_table = *old_table;
+        for (i = 0; i < new_size; i++) {
+            new_table->term[i] = old_table->term[i];
+        }
+    } else {
+        /*
+         * The size of the table has changed or an element has been
+         * deleted. Must rehash, by inserting all old terms into the
+         * new (empty) table.
+         */
+        new_table->allocated = new_size;
+        new_table->num_entries = old_table->num_entries;
+        new_table->mask = new_size - 1;
+        for (i = 0; i < new_size; i++) {
+            new_table->term[i] = NIL;
+        }
+        for (i = 0; i < old_size; i++) {
+            if (is_tuple(old_table->term[i])) {
+                Eterm key = tuple_val(old_table->term[i])[1];
+                Uint entry_index = lookup(new_table, key);
+                ASSERT(is_nil(new_table->term[entry_index]));
+                new_table->term[entry_index] = old_table->term[i];
+            }
+        }
+    }
+    new_table->first_to_delete = 0;
+    new_table->num_to_delete = 0;
+    erts_atomic_init_nob(&new_table->refc, (erts_aint_t)1);
+    return new_table;
+}
+
+static void
+mark_for_deletion(HashTable* hash_table, Uint entry_index)
+{
+    hash_table->first_to_delete = entry_index;
+    hash_table->num_to_delete = 1;
+}
+
+static ErtsLiteralArea*
+term_to_area(Eterm tuple)
+{
+    ASSERT(is_tuple_arity(tuple, 2));
+    return (ErtsLiteralArea *) (((char *) tuple_val(tuple)) -
+                                offsetof(ErtsLiteralArea, start));
+}
+
+static void
+table_updater(void* data)
+{
+    HashTable* old_table;
+    HashTable* new_table;
+
+    old_table = (HashTable *) erts_atomic_read_nob(&the_hash_table);
+    new_table = (HashTable *) data;
+    ASSERT(new_table->num_to_delete == 0);
+    erts_atomic_set_nob(&the_hash_table, (erts_aint_t)new_table);
+    append_to_delete_queue(old_table);
+    erts_schedule_thr_prgr_later_op(table_deleter,
+                                    old_table,
+                                    &old_table->thr_prog_op);
+    release_update_permission(1);
+}
+
+static void
+table_deleter(void* data)
+{
+    HashTable* old_table = (HashTable *) data;
+
+    dec_table_refc(NULL, old_table);
+}
+
+static void
+dec_table_refc(Process* c_p, HashTable* old_table)
+{
+    erts_aint_t refc = erts_atomic_dec_read_nob(&old_table->refc);
+
+    if (refc == 0) {
+        HashTable* to_delete;
+
+        while ((to_delete = next_to_delete()) != NULL) {
+            delete_table(c_p, to_delete);
+        }
+    }
+}
+
+static void
+delete_table(Process* c_p, HashTable* table)
+{
+    Uint idx = table->first_to_delete;
+    Uint n = table->num_to_delete;
+
+    /*
+     * There are no longer any references to this hash table.
+     *
+     * Any literals pointed for deletion can be queued for
+     * deletion and the table itself can be deallocated.
+     */
+
+#ifdef DEBUG
+    if (n == 1) {
+        ASSERT(is_tuple_arity(table->term[idx], 2));
+    }
+#endif
+
+    while (n > 0) {
+        Eterm term = table->term[idx];
+
+        if (is_tuple_arity(term, 2)) {
+            if (is_immed(tuple_val(term)[2])) {
+                erts_release_literal_area(term_to_area(term));
+            } else {
+                erts_queue_release_literals(c_p, term_to_area(term));
+            }
+        }
+        idx++, n--;
+    }
+    erts_free(ERTS_ALC_T_PERSISTENT_TERM, table);
+}
+
+/*
+ * Caller *must* yield if this function returns 0.
+ */
+
+static int
+try_seize_update_permission(Process* c_p)
+{
+    int success;
+
+    ASSERT(!erts_thr_progress_is_blocking()); /* to avoid deadlock */
+    ASSERT(c_p != NULL);
+
+    erts_mtx_lock(&update_table_permission_mtx);
+    ASSERT(updater_process != c_p);
+    success = (updater_process == NULL);
+    if (success) {
+        updater_process = c_p;
+    } else {
+        struct update_queue_item* qitem;
+        qitem = erts_alloc(ERTS_ALC_T_PERSISTENT_LOCK_Q, sizeof(*qitem));
+        qitem->p = c_p;
+        erts_proc_inc_refc(c_p);
+        qitem->next = update_queue;
+        update_queue = qitem;
+        erts_suspend(c_p, ERTS_PROC_LOCK_MAIN, NULL);
+    }
+    erts_mtx_unlock(&update_table_permission_mtx);
+    return success;
+}
+
+static void
+release_update_permission(int release_updater)
+{
+    erts_mtx_lock(&update_table_permission_mtx);
+    ASSERT(updater_process != NULL);
+
+    if (release_updater) {
+        erts_proc_lock(updater_process, ERTS_PROC_LOCK_STATUS);
+        if (!ERTS_PROC_IS_EXITING(updater_process)) {
+            erts_resume(updater_process, ERTS_PROC_LOCK_STATUS);
+        }
+        erts_proc_unlock(updater_process, ERTS_PROC_LOCK_STATUS);
+    }
+    updater_process = NULL;
+
+    while (update_queue != NULL) { /* Unleash the entire herd */
+	struct update_queue_item* qitem = update_queue;
+	erts_proc_lock(qitem->p, ERTS_PROC_LOCK_STATUS);
+	if (!ERTS_PROC_IS_EXITING(qitem->p)) {
+	    erts_resume(qitem->p, ERTS_PROC_LOCK_STATUS);
+	}
+	erts_proc_unlock(qitem->p, ERTS_PROC_LOCK_STATUS);
+	update_queue = qitem->next;
+	erts_proc_dec_refc(qitem->p);
+	erts_free(ERTS_ALC_T_PERSISTENT_LOCK_Q, qitem);
+    }
+    erts_mtx_unlock(&update_table_permission_mtx);
+}
+
+static void
+suspend_updater(Process* c_p)
+{
+#ifdef DEBUG
+    ASSERT(c_p != NULL);
+    erts_mtx_lock(&update_table_permission_mtx);
+    ASSERT(updater_process == c_p);
+    erts_mtx_unlock(&update_table_permission_mtx);
+#endif
+    erts_suspend(c_p, ERTS_PROC_LOCK_MAIN, NULL);
+}
+
+static void
+append_to_delete_queue(HashTable* table)
+{
+    erts_mtx_lock(&delete_queue_mtx);
+    table->delete_next = NULL;
+    *delete_queue_tail = table;
+    delete_queue_tail = &table->delete_next;
+    erts_mtx_unlock(&delete_queue_mtx);
+}
+
+static HashTable*
+next_to_delete(void)
+{
+    HashTable* table;
+
+    erts_mtx_lock(&delete_queue_mtx);
+    table = delete_queue_head;
+    if (table) {
+        if (erts_atomic_read_nob(&table->refc)) {
+            /*
+             * This hash table is still referenced. Hash tables
+             * must be deleted in order, so we return a NULL
+             * pointer.
+             */
+            table = NULL;
+        } else {
+            /*
+             * Remove the first hash table from the queue.
+             */
+            delete_queue_head = table->delete_next;
+            if (delete_queue_head == NULL) {
+                delete_queue_tail = &delete_queue_head;
+            }
+        }
+    }
+    erts_mtx_unlock(&delete_queue_mtx);
+    return table;
+}
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index 57c6c10c7f..f687dcf335 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -354,6 +354,7 @@ erl_init(int ncpu,
     erts_init_bif();
     erts_init_bif_chksum();
     erts_init_bif_binary();
+    erts_init_bif_persistent_term();
     erts_init_bif_re();
     erts_init_unicode(); /* after RE to get access to PCRE unicode */
     erts_init_external();
diff --git a/erts/emulator/beam/erl_lock_check.c b/erts/emulator/beam/erl_lock_check.c
index 463ae898a3..1416c5f96c 100644
--- a/erts/emulator/beam/erl_lock_check.c
+++ b/erts/emulator/beam/erl_lock_check.c
@@ -97,6 +97,8 @@ static erts_lc_lock_order_t erts_lock_order[] = {
     {	"proc_btm",				"pid"			},
     {	"dist_entry",				"address"		},
     {	"dist_entry_links",			"address"		},
+    {   "update_persistent_term_permission",    NULL                    },
+    {   "persistent_term_delete_permission",    NULL                    },
     {   "code_write_permission",                NULL                    },
     {	"purge_state",		      		NULL			},
     {	"proc_status",				"pid"			},
diff --git a/erts/emulator/beam/erl_process_dump.c b/erts/emulator/beam/erl_process_dump.c
index 243db4c734..ac5054ea10 100644
--- a/erts/emulator/beam/erl_process_dump.c
+++ b/erts/emulator/beam/erl_process_dump.c
@@ -58,6 +58,7 @@ static void dump_externally(fmtfn_t to, void *to_arg, Eterm term);
 static void mark_literal(Eterm* ptr);
 static void init_literal_areas(void);
 static void dump_literals(fmtfn_t to, void *to_arg);
+static void dump_persistent_terms(fmtfn_t to, void *to_arg);
 static void dump_module_literals(fmtfn_t to, void *to_arg,
                                  ErtsLiteralArea* lit_area);
 
@@ -74,6 +75,7 @@ erts_deep_process_dump(fmtfn_t to, void *to_arg)
 
     all_binaries = NULL;
     init_literal_areas();
+    erts_init_persistent_dumping();
 
     for (i = 0; i < max; i++) {
 	Process *p = erts_pix2proc(i);
@@ -93,6 +95,7 @@ erts_deep_process_dump(fmtfn_t to, void *to_arg)
        }
     }
 
+    dump_persistent_terms(to, to_arg);
     dump_literals(to, to_arg);
     dump_binaries(to, to_arg, all_binaries);
 }
@@ -775,6 +778,9 @@ init_literal_areas(void)
     qsort(lit_areas, num_lit_areas, sizeof(ErtsLiteralArea *),
           compare_areas);
 
+    qsort(erts_persistent_areas, erts_num_persistent_areas,
+          sizeof(ErtsLiteralArea *), compare_areas);
+
     erts_runlock_old_code(code_ix);
 }
 
@@ -796,6 +802,13 @@ static void mark_literal(Eterm* ptr)
 
     ap = bsearch(ptr, lit_areas, num_lit_areas, sizeof(ErtsLiteralArea*),
                  search_areas);
+    if (ap == 0) {
+        ap = bsearch(ptr, erts_persistent_areas,
+                     erts_num_persistent_areas,
+                     sizeof(ErtsLiteralArea*),
+                     search_areas);
+    }
+
 
     /*
      * If the literal was created by native code, this search will not
@@ -807,12 +820,12 @@ static void mark_literal(Eterm* ptr)
     }
 }
 
-
 static void
 dump_literals(fmtfn_t to, void *to_arg)
 {
     ErtsCodeIndex code_ix;
     int i;
+    Uint idx;
 
     code_ix = erts_active_code_ix();
     erts_rlock_old_code(code_ix);
@@ -825,6 +838,28 @@ dump_literals(fmtfn_t to, void *to_arg)
     }
 
     erts_runlock_old_code(code_ix);
+
+    for (idx = 0; idx < erts_num_persistent_areas; idx++) {
+        dump_module_literals(to, to_arg, erts_persistent_areas[idx]);
+    }
+}
+
+static void
+dump_persistent_terms(fmtfn_t to, void *to_arg)
+{
+    Uint idx;
+
+    erts_print(to, to_arg, "=persistent_terms\n");
+
+    for (idx = 0; idx < erts_num_persistent_areas; idx++) {
+        ErtsLiteralArea* ap = erts_persistent_areas[idx];
+        Eterm tuple = make_tuple(ap->start);
+        Eterm* tup_val = tuple_val(tuple);
+
+	dump_element(to, to_arg, tup_val[1]);
+        erts_putc(to, to_arg, '|');
+	dump_element_nl(to, to_arg, tup_val[2]);
+    }
 }
 
 static void
@@ -963,7 +998,8 @@ dump_module_literals(fmtfn_t to, void *to_arg, ErtsLiteralArea* lit_area)
                     }
                     erts_putc(to, to_arg, '\n');
                 }
-            } else if (is_export_header(w)) {
+            } else {
+                /* Dump everything else in the external format */
                 dump_externally(to, to_arg, term);
                 erts_putc(to, to_arg, '\n');
             }
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 21ae205237..0631404599 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -906,6 +906,8 @@ typedef struct ErtsLiteralArea_ {
     Eterm start[1]; /* beginning of area */
 } ErtsLiteralArea;
 
+void erts_queue_release_literals(Process *c_p, ErtsLiteralArea* literals);
+
 #define ERTS_LITERAL_AREA_ALLOC_SIZE(N) \
     (sizeof(ErtsLiteralArea) + sizeof(Eterm)*((N) - 1))
 
@@ -1001,6 +1003,7 @@ typedef struct {
     Uint literal_size;
     Eterm *lit_purge_ptr;
     Uint lit_purge_sz;
+    int copy_literals;
 } erts_shcopy_t;
 
 #define INITIALIZE_SHCOPY(info)						\
@@ -1010,6 +1013,7 @@ typedef struct {
 	info.bitstore_start = info.bitstore_default;			\
 	info.shtable_start = info.shtable_default;			\
 	info.literal_size = 0;						\
+	info.copy_literals = 0;						\
 	if (larea__) {							\
 	    info.lit_purge_ptr = &larea__->start[0];			\
 	    info.lit_purge_sz = larea__->end - info.lit_purge_ptr;	\
@@ -1238,6 +1242,13 @@ Sint erts_re_set_loop_limit(Sint limit);
 void erts_init_bif_binary(void);
 Sint erts_binary_set_loop_limit(Sint limit);
 
+/* erl_bif_persistent.c */
+void erts_init_bif_persistent_term(void);
+Uint erts_persistent_term_count(void);
+void erts_init_persistent_dumping(void);
+extern ErtsLiteralArea** erts_persistent_areas;
+extern Uint erts_num_persistent_areas;
+
 /* external.c */
 void erts_init_external(void);
 
diff --git a/erts/emulator/test/Makefile b/erts/emulator/test/Makefile
index bf00de2204..d201ea6ee1 100644
--- a/erts/emulator/test/Makefile
+++ b/erts/emulator/test/Makefile
@@ -92,6 +92,7 @@ MODULES= \
 	port_SUITE \
 	port_bif_SUITE \
 	prim_eval_SUITE \
+	persistent_term_SUITE \
 	process_SUITE \
 	pseudoknot_SUITE \
 	receive_SUITE \
diff --git a/erts/emulator/test/persistent_term_SUITE.erl b/erts/emulator/test/persistent_term_SUITE.erl
new file mode 100644
index 0000000000..58cd3276b0
--- /dev/null
+++ b/erts/emulator/test/persistent_term_SUITE.erl
@@ -0,0 +1,614 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2017. All Rights Reserved.
+%%
+%% Licensed under the Apache License, Version 2.0 (the "License");
+%% you may not use this file except in compliance with the License.
+%% You may obtain a copy of the License at
+%5
+%%     http://www.apache.org/licenses/LICENSE-2.0
+%%
+%% Unless required by applicable law or agreed to in writing, software
+%% distributed under the License is distributed on an "AS IS" BASIS,
+%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+%% See the License for the specific language governing permissions and
+%% limitations under the License.
+%%
+%% %CopyrightEnd%
+%%
+
+-module(persistent_term_SUITE).
+-include_lib("common_test/include/ct.hrl").
+
+-export([all/0,suite/0,
+	 basic/1,purging/1,sharing/1,get_trapping/1,
+         info/1,info_trapping/1,killed_while_trapping/1,
+         off_heap_values/1,keys/1,collisions/1,
+         init_restart/1]).
+
+%%
+-export([test_init_restart_cmd/1]).
+
+suite() ->
+    [{ct_hooks,[ts_install_cth]},
+     {timetrap,{minutes,10}}].
+
+all() ->
+    [basic,purging,sharing,get_trapping,info,info_trapping,
+     killed_while_trapping,off_heap_values,keys,collisions,
+     init_restart].
+
+basic(_Config) ->
+    Chk = chk(),
+    N = 777,
+    Seq = lists:seq(1, N),
+    par(2, N, Seq),
+    seq(3, Seq),
+    seq(3, Seq),                                %Same values.
+    _ = [begin
+             Key = {?MODULE,{key,I}},
+             true = persistent_term:erase(Key),
+             false = persistent_term:erase(Key),
+             {'EXIT',{badarg,_}} = (catch persistent_term:get(Key))
+         end || I <- Seq],
+    [] = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    chk(Chk).
+
+par(C, N, Seq) ->
+    _ = [spawn_link(fun() ->
+                            ok = persistent_term:put({?MODULE,{key,I}},
+                                                     {value,C*I})
+                    end) || I <- Seq],
+    Result = wait(N),
+    _ = [begin
+             Double = C*I,
+             {{?MODULE,{key,I}},{value,Double}} = Res
+         end || {I,Res} <- lists:zip(Seq, Result)],
+    ok.
+
+seq(C, Seq) ->
+    _ = [ok = persistent_term:put({?MODULE,{key,I}}, {value,C*I}) ||
+            I <- Seq],
+    All = persistent_term:get(),
+    All = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    All = [{Key,persistent_term:get(Key)} || {Key,_} <- All],
+    Result = lists:sort(All),
+    _ = [begin
+             Double = C*I,
+             {{?MODULE,{key,I}},{value,Double}} = Res
+         end || {I,Res} <- lists:zip(Seq, Result)],
+    ok.
+
+wait(N) ->
+    All = [P || {{?MODULE,_},_}=P <- persistent_term:get()],
+    case length(All) of
+        N ->
+            All = [{Key,persistent_term:get(Key)} || {Key,_} <- All],
+            lists:sort(All);
+        _ ->
+            receive after 10 -> ok end,
+            wait(N)
+    end.
+
+%% Make sure that terms that have been erased are copied into all
+%% processes that still hold a pointer to them.
+
+purging(_Config) ->
+    Chk = chk(),
+    do_purging(fun(K) -> persistent_term:put(K, {?MODULE,new}) end,
+               replaced),
+    do_purging(fun persistent_term:erase/1, erased),
+    chk(Chk).
+
+do_purging(Eraser, Type) ->
+    Parent = self(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, {term,[<<"abc",0:777/unit:8>>]}),
+    Ps0 = [spawn_monitor(fun() -> purging_tester(Parent, Key) end) ||
+              _ <- lists:seq(1, 50)],
+    Ps = maps:from_list(Ps0),
+    purging_recv(gotten, Ps),
+    Eraser(Key),
+    _ = [P ! {Parent,Type} || P <- maps:keys(Ps)],
+    purging_wait(Ps).
+
+purging_recv(Tag, Ps) when map_size(Ps) > 0 ->
+    receive
+        {Pid,Tag} ->
+            true = is_map_key(Pid, Ps),
+            purging_recv(Tag, maps:remove(Pid, Ps))
+    end;
+purging_recv(_, _) -> ok.
+
+purging_wait(Ps) when map_size(Ps) > 0 ->
+    receive
+        {'DOWN',Ref,process,Pid,Reason} ->
+            normal = Reason,
+            Ref = map_get(Pid, Ps),
+            purging_wait(maps:remove(Pid, Ps))
+    end;
+purging_wait(_) -> ok.
+
+purging_tester(Parent, Key) ->
+    Term = persistent_term:get(Key),
+    purging_check_term(Term),
+    0 = erts_debug:size_shared(Term),
+    Parent ! {self(),gotten},
+    receive
+        {Parent,erased} ->
+            {'EXIT',{badarg,_}} = (catch persistent_term:get(Key)),
+            purging_tester_1(Term);
+        {Parent,replaced} ->
+            {?MODULE,new} = persistent_term:get(Key),
+            purging_tester_1(Term)
+    end.
+
+%% Wait for the term to be copied into this process.
+purging_tester_1(Term) ->
+    purging_check_term(Term),
+    receive after 1 -> ok end,
+    case erts_debug:size_shared(Term) of
+        0 ->
+            purging_tester_1(Term);
+        Size ->
+            %% The term has been copied into this process.
+            purging_check_term(Term),
+            Size = erts_debug:size(Term)
+    end.
+
+purging_check_term({term,[<<"abc",0:777/unit:8>>]}) ->
+    ok.
+
+%% Test that sharing is preserved when storing terms.
+
+sharing(_Config) ->
+    Chk = chk(),
+    Depth = 10,
+    Size = 2*Depth,
+    Shared = lists:foldl(fun(_, A) -> [A|A] end,
+                         [], lists:seq(1, Depth)),
+    Size = erts_debug:size(Shared),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, Shared),
+    SharedStored = persistent_term:get(Key),
+    Size = erts_debug:size(SharedStored),
+    0 = erts_debug:size_shared(SharedStored),
+
+    {Pid,Ref} = spawn_monitor(fun() ->
+                                      Term = persistent_term:get(Key),
+                                      Size = erts_debug:size(Term),
+                                      0 = erts_debug:size_shared(Term),
+                                      true = Term =:= SharedStored
+                              end),
+    receive
+        {'DOWN',Ref,process,Pid,normal} ->
+            true = persistent_term:erase(Key),
+            Size = erts_debug:size(SharedStored),
+            chk(Chk)
+    end.
+
+%% Test trapping of persistent_term:get/0.
+
+get_trapping(_Config) ->
+    Chk = chk(),
+
+    %% Assume that the get/0 traps after 4000 iterations
+    %% in a non-debug emulator.
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 10000;
+            _ -> 1000
+        end,
+    spawn_link(fun() -> get_trapping_create(N) end),
+    All = do_get_trapping(N, []),
+    N = get_trapping_check_result(lists:sort(All), 1),
+    erlang:garbage_collect(),
+    get_trapping_erase(N),
+    chk(Chk).
+
+do_get_trapping(N, Prev) ->
+    case persistent_term:get() of
+        Prev when length(Prev) >= N ->
+            All = [P || {{?MODULE,{get_trapping,_}},_}=P <- Prev],
+            case length(All) of
+                N -> All;
+                _ -> do_get_trapping(N, Prev)
+            end;
+        New ->
+            receive after 1 -> ok end,
+            do_get_trapping(N, New)
+    end.
+
+get_trapping_create(0) ->
+    ok;
+get_trapping_create(N) ->
+    ok = persistent_term:put({?MODULE,{get_trapping,N}}, N),
+    get_trapping_create(N-1).
+
+get_trapping_check_result([{{?MODULE,{get_trapping,N}},N}|T], N) ->
+    get_trapping_check_result(T, N+1);
+get_trapping_check_result([], N) -> N-1.
+
+get_trapping_erase(0) ->
+    ok;
+get_trapping_erase(N) ->
+    true = persistent_term:erase({?MODULE,{get_trapping,N}}),
+    get_trapping_erase(N-1).
+
+%% Test retrieving information about persistent terms.
+
+info(_Config) ->
+    Chk = chk(),
+
+    %% White box test of info/0.
+    N = 100,
+    try
+        Overhead = info_literal_area_overhead(),
+        io:format("Overhead = ~p\n", [Overhead]),
+        info_wb(N, Overhead, info_info())
+    after
+        _ = [_ = persistent_term:erase({?MODULE,I}) ||
+                I <- lists:seq(1, N)]
+    end,
+
+    chk(Chk).
+
+%% White box test of persistent_term:info/0. We take into account
+%% that there might already exist persistent terms (created by the
+%% OTP standard libraries), but we assume that they are not
+%% changed during the execution of this test case.
+
+info_wb(0, _, _) ->
+    ok;
+info_wb(N, Overhead, {BaseCount,BaseMemory}) ->
+    Key = {?MODULE,N},
+    Value = lists:seq(1, N),
+    ok = persistent_term:put(Key, Value),
+
+    %% Calculate the extra memory needed for this term.
+    WordSize = erlang:system_info(wordsize),
+    ExtraMemory = Overhead + 2 * N * WordSize,
+
+    %% Call persistent_term:info/0.
+    {Count,Memory} = info_info(),
+
+    %% There should be one more persistent term.
+    Count = BaseCount + 1,
+
+    %% Verify that the amount of memory is correct.
+    case BaseMemory + ExtraMemory of
+        Memory ->
+            %% Exactly right. The size of the hash table was not changed.
+            ok;
+        Expected ->
+            %% The size of the hash table has been doubled to avoid filling
+            %% the table to more than 50 percent. The previous number
+            %% of entries must have been exactly half the size of the
+            %% hash table. The expected number of extra words added by
+            %% the resizing will be twice that number.
+            ExtraWords = BaseCount * 2,
+            true = ExtraWords * WordSize =:= (Memory - Expected)
+    end,
+    info_wb(N-1, Overhead, {Count,Memory}).
+
+info_info() ->
+    #{count:=Count,memory:=Memory} = persistent_term:info(),
+    true = is_integer(Count) andalso Count >= 0,
+    true = is_integer(Memory) andalso Memory >= 0,
+    {Count,Memory}.
+
+%% Calculate the number of extra bytes needed for storing each term in
+%% the literal, assuming that the key is a tuple of size 2 with
+%% immediate elements. The calculated number is the size of the
+%% ErtsLiteralArea struct excluding the storage for the literal term
+%% itself.
+
+info_literal_area_overhead() ->
+    Key1 = {?MODULE,1},
+    Key2 = {?MODULE,2},
+    #{memory:=Mem0} = persistent_term:info(),
+    ok = persistent_term:put(Key1, literal),
+    #{memory:=Mem1} = persistent_term:info(),
+    ok = persistent_term:put(Key2, literal),
+    #{memory:=Mem2} = persistent_term:info(),
+    true = persistent_term:erase(Key1),
+    true = persistent_term:erase(Key2),
+
+    %% The size of the hash table may have doubled when inserting
+    %% one of the keys. To avoiding counting the change in the hash
+    %% table size, take the smaller size increase.
+    min(Mem2-Mem1, Mem1-Mem0).
+
+%% Test trapping of persistent_term:info/0.
+
+info_trapping(_Config) ->
+    Chk = chk(),
+
+    %% Assume that the info/0 traps after 4000 iterations
+    %% in a non-debug emulator.
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 10000;
+            _ -> 1000
+        end,
+    spawn_link(fun() -> info_trapping_create(N) end),
+    All = do_info_trapping(N, 0),
+    N = info_trapping_check_result(lists:sort(All), 1),
+    erlang:garbage_collect(),
+    info_trapping_erase(N),
+    chk(Chk).
+
+do_info_trapping(N, PrevMem) ->
+    case info_info() of
+        {N,Mem} ->
+            true = Mem >= PrevMem,
+            All = [P || {{?MODULE,{info_trapping,_}},_}=P <- persistent_term:get()],
+            case length(All) of
+                N -> All;
+                _ -> do_info_trapping(N, PrevMem)
+            end;
+        {_,Mem} ->
+            true = Mem >= PrevMem,
+            receive after 1 -> ok end,
+            do_info_trapping(N, Mem)
+    end.
+
+info_trapping_create(0) ->
+    ok;
+info_trapping_create(N) ->
+    ok = persistent_term:put({?MODULE,{info_trapping,N}}, N),
+    info_trapping_create(N-1).
+
+info_trapping_check_result([{{?MODULE,{info_trapping,N}},N}|T], N) ->
+    info_trapping_check_result(T, N+1);
+info_trapping_check_result([], N) -> N-1.
+
+info_trapping_erase(0) ->
+    ok;
+info_trapping_erase(N) ->
+    true = persistent_term:erase({?MODULE,{info_trapping,N}}),
+    info_trapping_erase(N-1).
+
+%% Test that hash tables are deallocated if a process running
+%% persistent_term:get/0 is killed.
+
+killed_while_trapping(_Config) ->
+    Chk = chk(),
+    N = case test_server:timetrap_scale_factor() of
+            1 -> 20000;
+            _ -> 2000
+        end,
+    kwt_put(N),
+    kwt_spawn(10),
+    kwt_erase(N),
+    chk(Chk).
+
+kwt_put(0) ->
+    ok;
+kwt_put(N) ->
+    ok = persistent_term:put({?MODULE,{kwt,N}}, N),
+    kwt_put(N-1).
+
+kwt_spawn(0) ->
+    ok;
+kwt_spawn(N) ->
+    Pids = [spawn(fun kwt_getter/0) || _ <- lists:seq(1, 20)],
+    erlang:yield(),
+    _ = [exit(Pid, kill) || Pid <- Pids],
+    kwt_spawn(N-1).
+
+kwt_getter() ->
+    _ = persistent_term:get(),
+    kwt_getter().
+
+kwt_erase(0) ->
+    ok;
+kwt_erase(N) ->
+    true = persistent_term:erase({?MODULE,{kwt,N}}),
+    kwt_erase(N-1).
+
+%% Test storing off heap values (such as ref-counted binaries).
+
+off_heap_values(_Config) ->
+    Chk = chk(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    Val = {a,list_to_binary(lists:seq(0, 255)),make_ref(),fun() -> ok end},
+    ok = persistent_term:put(Key, Val),
+    FetchedVal = persistent_term:get(Key),
+    Val = FetchedVal,
+    true = persistent_term:erase(Key),
+    off_heap_values_wait(FetchedVal, Val),
+    chk(Chk).
+
+off_heap_values_wait(FetchedVal, Val) ->
+    case erts_debug:size_shared(FetchedVal) of
+        0 ->
+            Val = FetchedVal,
+            ok;
+        _ ->
+            erlang:yield(),
+            off_heap_values_wait(FetchedVal, Val)
+    end.
+
+%% Test some more data types as keys. Use the module name as a key
+%% to minimize the risk of collision with any key used
+%% by the OTP libraries.
+
+keys(_Config) ->
+    Chk = chk(),
+    do_key(?MODULE),
+    do_key([?MODULE]),
+    do_key(?MODULE_STRING),
+    do_key(list_to_binary(?MODULE_STRING)),
+    chk(Chk).
+
+do_key(Key) ->
+    Val = term_to_binary(Key),
+    ok = persistent_term:put(Key, Val),
+    StoredVal = persistent_term:get(Key),
+    Val = StoredVal,
+    true = persistent_term:erase(Key).
+
+%% Create persistent terms with keys that are known to collide.
+%% Delete them in random order, making sure that all others
+%% terms can still be found.
+
+collisions(_Config) ->
+    Chk = chk(),
+
+    %% Create persistent terms with random keys.
+    Keys = lists:flatten(colliding_keys()),
+    Kvs = [{K,rand:uniform(1000)} || K <- Keys],
+    _ = [ok = persistent_term:put(K, V) || {K,V} <- Kvs],
+    _ = [V = persistent_term:get(K) || {K,V} <- Kvs],
+
+    %% Now delete the persistent terms in random order.
+    collisions_delete(lists:keysort(2, Kvs)),
+
+    chk(Chk).
+
+collisions_delete([{Key,Val}|Kvs]) ->
+    Val = persistent_term:get(Key),
+    true = persistent_term:erase(Key),
+    true = lists:sort(persistent_term:get()) =:= lists:sort(Kvs),
+    _ = [V = persistent_term:get(K) || {K,V} <- Kvs],
+    collisions_delete(Kvs);
+collisions_delete([]) ->
+    ok.
+
+colliding_keys() ->
+    %% Collisions found by Jesper L. Andersen for breaking maps.
+    L = [[764492191,2361333849],
+         [49527266765044,90940896816021,20062927283041,267080852079651],
+         [249858369443708,206247021789428,20287304470696,25847120931175],
+         [10645228898670,224705626119556,267405565521452,258214397180678],
+         [264783762221048,166955943492306,98802957003141,102012488332476],
+         [69425677456944,177142907243411,137138950917722,228865047699598],
+         [116031213307147,29203342183358,37406949328742,255198080174323],
+         [200358182338308,235207156008390,120922906095920,116215987197289],
+         [58728890318426,68877471005069,176496507286088,221041411345780],
+         [91094120814795,50665258299931,256093108116737,19777509566621],
+         [74646746200247,98350487270564,154448261001199,39881047281135],
+         [23408943649483,164410325820923,248161749770122,274558342231648],
+         [169531547115055,213630535746863,235098262267796,200508473898303],
+         [235098564415817,85039146398174,51721575960328,173069189684390],
+         [176136386396069,155368359051606,147817099696487,265419485459634],
+         [137542881551462,40028925519736,70525669519846,63445773516557],
+         [173854695142814,114282444507812,149945832627054,99605565798831],
+         [177686773562184,127158716984798,132495543008547],
+         [227073396444896,139667311071766,158915951283562],
+         [26212438434289,94902985796531,198145776057315],
+         [266279278943923,58550737262493,74297973216378],
+         [32373606512065,131854353044428,184642643042326],
+         [34335377662439,85341895822066,273492717750246]],
+
+    %% Verify that the keys still collide (this will fail if the
+    %% internal hash function has been changed).
+    erts_debug:set_internal_state(available_internal_state, true),
+    try
+        case erlang:system_info(wordsize) of
+            8 ->
+                verify_colliding_keys(L);
+            4 ->
+                %% Not guaranteed to collide on a 32-bit system.
+                ok
+        end
+    after
+        erts_debug:set_internal_state(available_internal_state, false)
+    end,
+
+    L.
+
+verify_colliding_keys([[K|Ks]|Gs]) ->
+    Hash = internal_hash(K),
+    [Hash] = lists:usort([internal_hash(Key) || Key <- Ks]),
+    verify_colliding_keys(Gs);
+verify_colliding_keys([]) ->
+    ok.
+
+internal_hash(Term) ->
+    erts_debug:get_internal_state({internal_hash,Term}).
+
+%% Test that all persistent terms are erased by init:restart/0.
+
+init_restart(_Config) ->
+    File = "command_file",
+    ok = file:write_file(File, term_to_binary(restart)),
+    {ok,[[Erl]]} = init:get_argument(progname),
+    ModPath = filename:dirname(code:which(?MODULE)),
+    Cmd = Erl ++ " -pa " ++ ModPath ++ " -noshell "
+        "-run " ++ ?MODULE_STRING ++ " test_init_restart_cmd " ++
+        File,
+    io:format("~s\n", [Cmd]),
+    Expected = "12ok",
+    case os:cmd(Cmd) of
+        Expected ->
+            ok;
+        Actual ->
+            io:format("Expected: ~s", [Expected]),
+            io:format("Actual:   ~s\n", [Actual]),
+            ct:fail(unexpected_output)
+    end.
+
+test_init_restart_cmd([File]) ->
+    try
+        do_test_init_restart_cmd(File)
+    catch
+        C:R ->
+            io:format("\n~p ~p\n", [C,R]),
+            halt()
+    end,
+    receive
+        _ -> ok
+    end.
+
+do_test_init_restart_cmd(File) ->
+    {ok,Bin} = file:read_file(File),
+    Seq = lists:seq(1, 50),
+    case binary_to_term(Bin) of
+        restart ->
+            _ = [persistent_term:put({?MODULE,I}, {value,I}) ||
+                    I <- Seq],
+            ok = file:write_file(File, term_to_binary(was_restarted)),
+            io:put_chars("1"),
+            init:restart(),
+            receive
+                _ -> ok
+            end;
+        was_restarted ->
+            io:put_chars("2"),
+            ok = file:delete(File),
+            _ = [begin
+                     Key = {?MODULE,I},
+                     {'EXIT',{badarg,_}} = (catch persistent_term:get(Key))
+                 end || I <- Seq],
+            io:put_chars("ok"),
+            init:stop()
+    end.
+
+%% Check that there is the same number of persistents terms before
+%% and after each test case.
+
+chk() ->
+    persistent_term:info().
+
+chk(Chk) ->
+    Chk = persistent_term:info(),
+    Key = {?MODULE,?FUNCTION_NAME},
+    ok = persistent_term:put(Key, {term,Chk}),
+    Term = persistent_term:get(Key),
+    true = persistent_term:erase(Key),
+    chk_not_stuck(Term),
+    ok.
+
+chk_not_stuck(Term) ->
+    %% Hash tables to be deleted are put onto a queue.
+    %% Make sure that the queue isn't stuck by a table with
+    %% a non-zero ref count.
+
+    case erts_debug:size_shared(Term) of
+        0 ->
+            erlang:yield(),
+            chk_not_stuck(Term);
+        _ ->
+            ok
+    end.