diff --git a/taskflow/engines/action_engine/graph_action.py b/taskflow/engines/action_engine/graph_action.py
index 0a21a0b2..914b0d22 100644
--- a/taskflow/engines/action_engine/graph_action.py
+++ b/taskflow/engines/action_engine/graph_action.py
@@ -41,28 +41,31 @@ class FutureGraphAction(object):
     def is_running(self):
         return self._storage.get_flow_state() == st.RUNNING
 
+    def _schedule(self, nodes):
+        """Schedule nodes for execution.
+
+        Returns list of futures.
+        """
+        futures = []
+        for node in nodes:
+            if isinstance(node, task.BaseTask):
+                future = self._schedule_task(node)
+            elif isinstance(node, r.Retry):
+                future = self._schedule_retry(node)
+            else:
+                raise TypeError("Unknown how to schedule node %s" % node)
+            if future is not None:
+                futures.append(future)
+            else:
+                next_nodes = self._analyzer.get_next_nodes(node)
+                futures.extend(self._schedule(next_nodes))
+        return futures
+
     def execute(self):
-
-        def schedule(nodes, not_done):
-            for node in nodes:
-                # Returns schedule function for current atom and
-                # executes scheduling
-                if isinstance(node, task.BaseTask):
-                    future = self._schedule_task(node)
-                elif isinstance(node, r.Retry):
-                    future = self._schedule_retry(node)
-                else:
-                    raise TypeError("Unknown how to schedule node %s" % node)
-                if future is not None:
-                    not_done.append(future)
-                else:
-                    schedule(self._analyzer.get_next_nodes(node), not_done)
-
-        not_done = []
         # Prepare flow to be resumed
         next_nodes = self._prepare_flow_for_resume()
         next_nodes.update(self._analyzer.get_next_nodes())
-        schedule(next_nodes, not_done)
+        not_done = self._schedule(next_nodes)
 
         failures = []
         while not_done:
@@ -85,7 +88,7 @@ class FutureGraphAction(object):
                 next_nodes.update(self._analyzer.get_next_nodes(node))
 
             if next_nodes and not failures and self.is_running():
-                schedule(next_nodes, not_done)
+                not_done.extend(self._schedule(next_nodes))
 
         if failures:
             misc.Failure.reraise_if_any(failures)