diff --git a/src/server/async/socket_server.cc b/src/server/async/socket_server.cc
index 9e17b6521..3c6b40ec0 100644
--- a/src/server/async/socket_server.cc
+++ b/src/server/async/socket_server.cc
@@ -574,7 +574,7 @@ bool SocketConnection::doGetBuffers(const json& root) {
   RESPONSE_ON_ERROR(bulk_store_->GetUnsafe(ids, unsafe, objects));
   VINEYARD_CHECK_OK(bulk_store_->MarkAsCold(ids, objects));
   for (size_t i = 0; i < objects.size(); ++i) {
-    if (objects[i]->pointer == nullptr) {
+    if (objects[i]->pointer == nullptr && objects[i]->data_size > 0) {
       VINEYARD_CHECK_OK(
           bulk_store_->ReloadColdObject(ids[i], objects[i], false));
       VINEYARD_CHECK_OK(bulk_store_->MarkAsCold(ids[i], objects[i]));
@@ -802,7 +802,7 @@ bool SocketConnection::doGetRemoteBuffers(const json& root) {
   RESPONSE_ON_ERROR(bulk_store_->GetUnsafe(ids, unsafe, objects));
   VINEYARD_CHECK_OK(bulk_store_->MarkAsCold(ids, objects));
   for (size_t i = 0; i < objects.size(); ++i) {
-    if (objects[i]->pointer == nullptr) {
+    if (objects[i]->pointer == nullptr && objects[i]->data_size > 0) {
       VINEYARD_CHECK_OK(
           bulk_store_->ReloadColdObject(ids[i], objects[i], false));
       VINEYARD_CHECK_OK(bulk_store_->MarkAsCold(ids[i], objects[i]));
diff --git a/src/server/memory/usage.h b/src/server/memory/usage.h
index ecbff4d98..e36e7c408 100644
--- a/src/server/memory/usage.h
+++ b/src/server/memory/usage.h
@@ -396,6 +396,7 @@ class ColdObjectTracker
     lru_map_t map_;
     lru_list_t list_;
     ska::flat_hash_map<ID, std::shared_ptr<P>> spilled_obj_;
+    friend class ColdObjectTracker;
   };
 
  public:
@@ -556,7 +557,8 @@ class ColdObjectTracker
    */
   uint8_t* AllocateMemoryWithSpill(const size_t size, int* fd,
                                    int64_t* map_size, ptrdiff_t* offset) {
-    std::lock_guard<std::mutex> locked(allocate_memory_mu_);
+    // std::lock_guard<std::mutex> locked(allocate_memory_mu_);
+    std::lock_guard<decltype(cold_obj_lru_.mu_)> locked(cold_obj_lru_.mu_);
     uint8_t* pointer = nullptr;
     std::cout << "Thread " << std::this_thread::get_id()
               << " before AllocateMemoryWithSpill;" << "size:" << size
@@ -574,7 +576,7 @@ class ColdObjectTracker
     //  2. memory usage is above upper bound
     if (pointer == nullptr ||
         BulkAllocator::Allocated() >= self().mem_spill_upper_bound_) {
-      //std::unique_lock<std::mutex> locked(spill_mu_);
+      // std::unique_lock<std::mutex> locked(spill_mu_);
 
       int64_t min_spill_size = 0;
       if (pointer == nullptr) {