fix: use correct type for _current_global_parameter_metas

Author: weixiao-huang

checkpoint_engine/ps.py

@@ -725,7 +725,12 @@ def gather_metas(self, checkpoint_name: str):
             if not self._global_device_uuids:
                 global_device_uuids.append(metas_buckets.device_uuid)
             if metas_buckets.memory_buffer_metas_list:
-                self._current_global_parameter_metas[i] = metas_buckets
+                # _current_global_parameter_metas value should be MemoryBufferMetaList, but metas_buckets is DataToGather
+                # so we need to convert it to MemoryBufferMetaList
+                self._current_global_parameter_metas[i] = MemoryBufferMetaList(
+                    memory_buffer_metas_list=metas_buckets.memory_buffer_metas_list,
+                    p2p_store_addr=metas_buckets.p2p_store_addr,
+                )
                 num_parameters += sum(len(x.metas) for x in metas_buckets.memory_buffer_metas_list)
         if not self._all_hosts:
             self._all_hosts = all_hosts