refactor: optimize buffer retrieval in document processing

Author: liuruibin

apps/application/flow/step_node/document_split_node/impl/base_document_split_node.py

@@ -47,9 +47,10 @@ def execute(self, document_list, knowledge_id, split_strategy, paragraph_title_r
         self.context['knowledge_id'] = knowledge_id
         file_list = self.workflow_manage.get_reference_field(document_list[0], document_list[1:])
         paragraph_list = []
-        get_buffer = FileBufferHandle().get_buffer
 
         for doc in file_list:
+            get_buffer = FileBufferHandle().get_buffer
+
             file_mem = bytes_to_uploaded_file(doc['content'].encode('utf-8'), doc['name'])
             result = default_split_handle.handle(file_mem, patterns, with_filter, limit, get_buffer, self._save_image)
             # 统一处理结果为列表