fix(core): Stop task process correctly in native Python runner (#20840)

packages/@n8n/task-runner-python/src/task_executor.py

@@ -160,6 +160,7 @@ class TaskExecutor:
 
             if process.is_alive():
                 process.kill()
+                process.join()
         except (ProcessLookupError, ConnectionError, BrokenPipeError):
             # subprocess is dead or unreachable
             pass

packages/@n8n/task-runner-python/src/task_runner.py

@@ -372,8 +372,7 @@ class TaskRunner:
 
         if task_state.status == TaskStatus.RUNNING:
             task_state.status = TaskStatus.ABORTING
-            self.executor.stop_process(task_state.process)
-
+            await asyncio.to_thread(self.executor.stop_process, task_state.process)
             self.logger.info(
                 LOG_TASK_CANCEL.format(task_id=task_id, **task_state.context())
             )