diff --git a/include/mimalloc.h b/include/mimalloc.h
index 7a58e54c..b0a20e9e 100644
--- a/include/mimalloc.h
+++ b/include/mimalloc.h
@@ -326,7 +326,13 @@ mi_decl_export void mi_heap_guarded_set_size_bound(mi_heap_t* heap, size_t min,
 //mi_decl_export void  mi_os_decommit(void* p, size_t size);
 
 mi_decl_export bool  mi_arena_unload(mi_arena_id_t arena_id, void** base, size_t* accessed_size, size_t* size);
-mi_decl_export bool  mi_arena_reload(void* start, size_t size, bool is_committed, bool is_large, bool is_zero, mi_arena_id_t* arena_id); 
+mi_decl_export bool  mi_arena_reload(void* start, size_t size, mi_arena_id_t* arena_id); 
+mi_decl_export bool  mi_heap_reload(mi_heap_t* heap, mi_arena_id_t arena);
+mi_decl_export void  mi_heap_unload(mi_heap_t* heap);
+
+// Is a pointer contained in the given arena area?
+mi_decl_export bool  mi_arena_contains(mi_arena_id_t arena_id, const void* p);
+
 
 // ------------------------------------------------------
 // Convenience
diff --git a/src/arena.c b/src/arena.c
index 869cba49..aa3c9175 100644
--- a/src/arena.c
+++ b/src/arena.c
@@ -492,7 +492,6 @@ void* _mi_arena_alloc_aligned( mi_subproc_t* subproc,
 
   // try to allocate in an arena if the alignment is small enough and the object is not too small (as for heap meta data)
   if (!mi_option_is_enabled(mi_option_disallow_arena_alloc) &&           // is arena allocation allowed?
-      req_arena == NULL &&                                               // not a specific arena?
       size >= MI_ARENA_MIN_OBJ_SIZE && size <= MI_ARENA_MAX_OBJ_SIZE &&  // and not too small/large
       alignment <= MI_ARENA_SLICE_ALIGN && align_offset == 0)            // and good alignment
   {
@@ -980,13 +979,21 @@ void _mi_arenas_collect(bool force_purge) {
   mi_arenas_try_purge(force_purge, force_purge /* visit all? */);
 }
 
+
+// Is a pointer contained in the given arena area?
+bool mi_arena_contains(mi_arena_id_t arena_id, const void* p) {
+  mi_arena_t* arena = _mi_arena_from_id(arena_id);
+  return (mi_arena_start(arena) <= (const uint8_t*)p &&
+          mi_arena_start(arena) + mi_size_of_slices(arena->slice_count) >(const uint8_t*)p);
+}
+
 // Is a pointer inside any of our arenas?
 bool _mi_arena_contains(const void* p) {
   mi_subproc_t* subproc = _mi_subproc();
   const size_t max_arena = mi_arenas_get_count(subproc);
   for (size_t i = 0; i < max_arena; i++) {
     mi_arena_t* arena = mi_atomic_load_ptr_acquire(mi_arena_t, &subproc->arenas[i]);
-    if (arena != NULL && mi_arena_start(arena) <= (const uint8_t*)p && mi_arena_start(arena) + mi_size_of_slices(arena->slice_count) >(const uint8_t*)p) {
+    if (arena != NULL && mi_arena_contains(arena,p)) {
       return true;
     }
   }
@@ -1636,7 +1643,7 @@ mi_decl_export bool mi_arena_unload(mi_arena_id_t arena_id, void** base, size_t*
   return true;
 }
 
-mi_decl_export bool mi_arena_reload(void* start, size_t size, bool is_committed, bool is_large, bool is_zero, mi_arena_id_t* arena_id) {
+mi_decl_export bool mi_arena_reload(void* start, size_t size, mi_arena_id_t* arena_id) {
   // assume the memory area is already containing the arena
   if (arena_id != NULL) { *arena_id = _mi_arena_id_none(); }
   if (start == NULL || size == 0) return false;
@@ -1658,13 +1665,10 @@ mi_decl_export bool mi_arena_reload(void* start, size_t size, bool is_committed,
     _mi_warning_message("the reloaded arena is not exclusive\n");
     return false;
   }
-  arena->memid.is_pinned = is_large;
-  arena->memid.initially_committed = is_committed;
-  arena->memid.initially_zero = is_zero;
+  
   arena->is_exclusive = true;
-  arena->is_large = is_large;
-  arena->subproc = NULL;
-  if (!mi_arena_add(_mi_subproc(), arena, arena_id)) {
+  arena->subproc = _mi_subproc();
+  if (!mi_arena_add(arena->subproc, arena, arena_id)) {
     return false;
   }
   mi_arena_pages_reregister(arena);
diff --git a/src/heap.c b/src/heap.c
index f47aaad9..03030b47 100644
--- a/src/heap.c
+++ b/src/heap.c
@@ -234,7 +234,7 @@ mi_heap_t* _mi_heap_create(int heap_tag, bool allow_destroy, mi_arena_id_t arena
   else {
     // heaps associated wita a specific arena are allocated in that arena
     // note: takes up at least one slice which is quite wasteful...
-    heap = (mi_heap_t*)_mi_arena_alloc(_mi_subproc(), sizeof(mi_heap_t), true, true, _mi_arena_from_id(arena_id), tld->thread_seq, &memid);
+    heap = (mi_heap_t*)_mi_arena_alloc(_mi_subproc(), _mi_align_up(sizeof(mi_heap_t),MI_ARENA_MIN_OBJ_SIZE), true, true, _mi_arena_from_id(arena_id), tld->thread_seq, &memid);
   }
   if (heap==NULL) {
     _mi_error_message(ENOMEM, "unable to allocate heap meta-data\n");
@@ -280,7 +280,7 @@ static void mi_heap_reset_pages(mi_heap_t* heap) {
 }
 
 // called from `mi_heap_destroy` and `mi_heap_delete` to free the internal heap resources.
-static void mi_heap_free(mi_heap_t* heap) {
+static void mi_heap_free(mi_heap_t* heap, bool do_free_mem) {
   mi_assert(heap != NULL);
   mi_assert_internal(mi_heap_is_initialized(heap));
   if (heap==NULL || !mi_heap_is_initialized(heap)) return;
@@ -307,7 +307,9 @@ static void mi_heap_free(mi_heap_t* heap) {
   mi_assert_internal(heap->tld->heaps != NULL);
 
   // and free the used memory
-  _mi_meta_free(heap, sizeof(*heap), heap->memid);
+  if (do_free_mem) {
+    _mi_meta_free(heap, sizeof(*heap), heap->memid);
+  }
 }
 
 // return a heap on the same thread as `heap` specialized for the specified tag (if it exists)
@@ -403,7 +405,7 @@ void mi_heap_destroy(mi_heap_t* heap) {
     #endif
     // free all pages
     _mi_heap_destroy_pages(heap);
-    mi_heap_free(heap);
+    mi_heap_free(heap,true);
   }
   #endif
 }
@@ -462,20 +464,11 @@ void mi_heap_delete(mi_heap_t* heap)
   mi_assert_expensive(mi_heap_is_valid(heap));
   if (heap==NULL || !mi_heap_is_initialized(heap)) return;
 
-  /*
-  mi_heap_t* bheap = heap->tld->heap_backing;
-  if (bheap != heap && mi_heaps_are_compatible(bheap,heap)) {
-    // transfer still used pages to the backing heap
-    mi_heap_absorb(bheap, heap);
-  }
-  else
-  */
-  {
-    // abandon all pages
-    _mi_heap_collect_abandon(heap);
-  }
+  // abandon all pages
+  _mi_heap_collect_abandon(heap);
+  
   mi_assert_internal(heap->page_count==0);
-  mi_heap_free(heap);
+  mi_heap_free(heap,true);
 }
 
 mi_heap_t* mi_heap_set_default(mi_heap_t* heap) {
@@ -489,7 +482,63 @@ mi_heap_t* mi_heap_set_default(mi_heap_t* heap) {
 }
 
 
+/* -----------------------------------------------------------
+  Load/unload heaps
+----------------------------------------------------------- */
+void mi_heap_unload(mi_heap_t* heap) {
+  mi_assert(mi_heap_is_initialized(heap));
+  mi_assert_expensive(mi_heap_is_valid(heap));
+  if (heap==NULL || !mi_heap_is_initialized(heap)) return;
+  if (heap->exclusive_arena == NULL) {
+    _mi_warning_message("cannot unload heaps that are not associated with an exclusive arena\n");
+    return;
+  }
+  
+  // abandon all pages so all thread'id in the pages are cleared
+  _mi_heap_collect_abandon(heap);
+  mi_assert_internal(heap->page_count==0);
 
+  // remove from heap list
+  mi_heap_free(heap, false /* but don't actually free the memory */);
+
+  // disassociate from the current thread-local and static state
+  heap->tld = NULL;
+  return;
+}
+
+bool mi_heap_reload(mi_heap_t* heap, mi_arena_id_t arena_id) {
+  mi_assert(mi_heap_is_initialized(heap));  
+  if (heap==NULL || !mi_heap_is_initialized(heap)) return false;
+  if (heap->exclusive_arena == NULL) {
+    _mi_warning_message("cannot reload heaps that were not associated with an exclusive arena\n");
+    return false;
+  }
+  if (heap->tld != NULL) {
+    _mi_warning_message("cannot reload heaps that were not unloaded first\n");
+    return false;
+  }
+  mi_arena_t* arena = _mi_arena_from_id(arena_id);
+  if (heap->exclusive_arena != arena) {
+    _mi_warning_message("trying to reload a heap at a different arena address: %p vs %p\n", heap->exclusive_arena, arena);
+    return false;
+  }
+
+  mi_assert_internal(heap->page_count==0);
+
+  // re-associate from the current thread-local and static state
+  heap->tld = _mi_tld();
+
+  // reinit direct pages (as we may be in a different process)
+  mi_assert_internal(heap->page_count == 0);
+  for (int i = 0; i < MI_PAGES_DIRECT; i++) {
+    heap->pages_free_direct[i] = (mi_page_t*)&_mi_page_empty;
+  }
+
+  // push on the thread local heaps list
+  heap->next = heap->tld->heaps;
+  heap->tld->heaps = heap;
+  return true;
+}
 
 /* -----------------------------------------------------------
   Analysis