DistArray::lazy_deleter waits for delayed sets

src/TiledArray/array_impl.h

@@ -632,6 +632,14 @@ class ArrayImpl : public TensorImpl<Policy> {
     return value;
   }
 
+  /// Reports the number of live DelayedSet requests for this object's
+  /// DistributedStorage
+
+  /// @return const reference to the atomic counter of live DelayedSet requests
+  const madness::AtomicInt& num_live_ds() const {
+    return data_.num_live_ds();
+  }
+
 };  // class ArrayImpl
 
 #ifndef TILEDARRAY_HEADER_ONLY

src/TiledArray/dist_array.h

@@ -142,6 +142,9 @@ class DistArray : public madness::archive::ParallelSerializableObject {
         const madness::uniqueidT id = pimpl->id();
         cleanup_counter_++;
 
+        // wait for all DelayedSet's to vanish
+        world.await([&]() { return (pimpl->num_live_ds() == 0); }, true);
+
         try {
           world.gop.lazy_sync(id, [pimpl]() {
             delete pimpl;

src/TiledArray/distributed_storage.h

@@ -293,6 +293,12 @@ class DistributedStorage : public madness::WorldObject<DistributedStorage<T> > {
     }
   }
 
+  /// Reports the number of live DelayedSet requests
+
+  /// @return const reference to the atomic counter of live DelayedSet requests
+  const madness::AtomicInt& num_live_ds() const {
+    return num_live_ds_;
+  }
 };  // class DistributedStorage
 
 }  // namespace detail