diff --git a/api/configs/feature/__init__.py b/api/configs/feature/__init__.py
index 93475226e8e69e..e79401bdfdabed 100644
--- a/api/configs/feature/__init__.py
+++ b/api/configs/feature/__init__.py
@@ -443,6 +443,7 @@ class WorkflowNodeExecutionConfig(BaseSettings):
     """
     Configuration for workflow node execution
     """
+
     MAX_SUBMIT_COUNT: PositiveInt = Field(
         description="Maximum number of submitted thread count in a ThreadPool for parallel node execution",
         default=100,
diff --git a/api/core/workflow/graph_engine/graph_engine.py b/api/core/workflow/graph_engine/graph_engine.py
index 0274ec0c39dc64..034b4bd3992dcb 100644
--- a/api/core/workflow/graph_engine/graph_engine.py
+++ b/api/core/workflow/graph_engine/graph_engine.py
@@ -53,12 +53,12 @@
 
 class GraphEngineThreadPool(ThreadPoolExecutor):
     def __init__(
-        self, 
-        max_workers=None, 
+        self,
+        max_workers=None,
         thread_name_prefix="",
-        initializer=None, 
-        initargs=(), 
-        max_submit_count=dify_config.MAX_SUBMIT_COUNT
+        initializer=None,
+        initargs=(),
+        max_submit_count=dify_config.MAX_SUBMIT_COUNT,
     ) -> None:
         super().__init__(max_workers, thread_name_prefix, initializer, initargs)
         self.max_submit_count = max_submit_count
diff --git a/api/core/workflow/nodes/iteration/iteration_node.py b/api/core/workflow/nodes/iteration/iteration_node.py
index af88a882fbc6dd..d935228c16abe9 100644
--- a/api/core/workflow/nodes/iteration/iteration_node.py
+++ b/api/core/workflow/nodes/iteration/iteration_node.py
@@ -163,8 +163,9 @@ def _run(self) -> Generator[NodeEvent | InNodeEvent, None, None]:
             if self.node_data.is_parallel:
                 futures: list[Future] = []
                 q: Queue = Queue()
-                thread_pool = GraphEngineThreadPool(max_workers=self.node_data.parallel_nums, 
-                                                    max_submit_count=dify_config.MAX_SUBMIT_COUNT)
+                thread_pool = GraphEngineThreadPool(
+                    max_workers=self.node_data.parallel_nums, max_submit_count=dify_config.MAX_SUBMIT_COUNT
+                )
                 for index, item in enumerate(iterator_list_value):
                     future: Future = thread_pool.submit(
                         self._run_single_iter_parallel,