feat(workflow): add thread pool

api/core/workflow/graph_engine/graph_engine.py

@@ -1,3 +1,4 @@
+from concurrent.futures import ThreadPoolExecutor, wait
 import logging
 import queue
 import threading
@@ -64,6 +65,8 @@ class GraphEngine:
             max_execution_steps: int,
             max_execution_time: int
     ) -> None:
+        ## init thread pool
+        self.thread_pool = ThreadPoolExecutor(max_workers=10)
         self.graph = graph
         self.init_params = GraphInitParams(
             tenant_id=tenant_id,
@@ -368,7 +371,7 @@ class GraphEngine:
         q: queue.Queue = queue.Queue()
 
         # Create a list to store the threads
-        threads = []
+        futures = []
 
         # new thread
         for edge in edge_mappings:
@@ -378,17 +381,16 @@ class GraphEngine:
             ):
                 continue
 
-            thread = threading.Thread(target=self._run_parallel_node, kwargs={
-                'flask_app': current_app._get_current_object(),  # type: ignore[attr-defined]
-                'q': q,
-                'parallel_id': parallel_id,
-                'parallel_start_node_id': edge.target_node_id,
-                'parent_parallel_id': in_parallel_id,
-                'parent_parallel_start_node_id': parallel_start_node_id,
-            })
-
-            threads.append(thread)
-            thread.start()
+            futures.append(
+                self.thread_pool.submit(self._run_parallel_node, **{
+                    'flask_app': current_app._get_current_object(),  # type: ignore[attr-defined]
+                    'q': q,
+                    'parallel_id': parallel_id,
+                    'parallel_start_node_id': edge.target_node_id,
+                    'parent_parallel_id': in_parallel_id,
+                    'parent_parallel_start_node_id': parallel_start_node_id,
+                })
+            )
 
         succeeded_count = 0
         while True:
@@ -401,7 +403,7 @@ class GraphEngine:
                 if event.parallel_id == parallel_id:
                     if isinstance(event, ParallelBranchRunSucceededEvent):
                         succeeded_count += 1
-                        if succeeded_count == len(threads):
+                        if succeeded_count == len(futures):
                             q.put(None)
 
                         continue
@@ -410,9 +412,8 @@ class GraphEngine:
             except queue.Empty:
                 continue
         
-        # Join all threads
-        for thread in threads:
-            thread.join()
+        # wait all threads
+        wait(futures)
 
         # get final node id
         final_node_id = parallel.end_to_node_id