Revert "Fix: iteration not in main thread pool" (#11358)

api/core/workflow/nodes/iteration/iteration_node.py

@@ -116,7 +116,7 @@ class IterationNode(BaseNode[IterationNodeData]):
         variable_pool.add([self.node_id, "item"], iterator_list_value[0])
 
         # init graph engine
-        from core.workflow.graph_engine.graph_engine import GraphEngine
+        from core.workflow.graph_engine.graph_engine import GraphEngine, GraphEngineThreadPool
 
         graph_engine = GraphEngine(
             tenant_id=self.tenant_id,
@@ -162,8 +162,7 @@ class IterationNode(BaseNode[IterationNodeData]):
             if self.node_data.is_parallel:
                 futures: list[Future] = []
                 q = Queue()
-                thread_pool = graph_engine.workflow_thread_pool_mapping[graph_engine.thread_pool_id]
-                thread_pool._max_workers = self.node_data.parallel_nums
+                thread_pool = GraphEngineThreadPool(max_workers=self.node_data.parallel_nums, max_submit_count=100)
                 for index, item in enumerate(iterator_list_value):
                     future: Future = thread_pool.submit(
                         self._run_single_iter_parallel,