message: add TF_LOCKS_EXCLUDED to MutableDenseHashTable::MemoryUsed
diff: @@ -557,7 +557,7 @@ class MutableDenseHashTable final : public LookupInterface {
  TensorShape value_shape() const override { return value_shape_; }
  - int64 MemoryUsed() const override {
  + int64 MemoryUsed() const override TF_LOCKS_EXCLUDED(mu_) {
  tf_shared_lock l(mu_);
  return sizeof(MutableDenseHashTable) + key_buckets_.AllocatedBytes() +
  value_buckets_.AllocatedBytes() + empty_key_.AllocatedBytes();
  