[GitHub] [airflow] XD-DENG commented on a change in pull request #12815: Cleanup & improvements around scheduling

[GitBox <gi...@apache.org>]

XD-DENG commented on a change in pull request #12815:
URL: https://github.com/apache/airflow/pull/12815#discussion_r536281388



##########
File path: airflow/models/dagrun.py
##########
@@ -718,19 +718,20 @@ def schedule_tis(self, schedulable_tis: Iterable[TI], session: Session = None) -
         All the TIs should belong to this DagRun, but this code is in the hot-path, this is not checked -- it
         is the caller's responsibility to call this function only with TIs from a single dag run.
         """
-        # Get list of TIs that do not need to executed, these are
+        # Get list of TI IDs that do not need to executed, these are
         # tasks using DummyOperator and without on_execute_callback / on_success_callback
-        dummy_tis = {
-            ti
-            for ti in schedulable_tis
+        dummy_ti_ids = []
+        schedulable_ti_ids = []
+        for ti in schedulable_tis:
             if (
                 ti.task.inherits_from_dummy_operator
                 and not ti.task.on_execute_callback
                 and not ti.task.on_success_callback
-            )
-        }
+            ):
+                dummy_ti_ids.append(ti.task_id)
+            else:
+                schedulable_ti_ids.append(ti.task_id)
 
-        schedulable_ti_ids = [ti.task_id for ti in schedulable_tis if ti not in dummy_tis]
         count = 0

Review comment:
       This change is to ensure we traverse `schedulable_tis` only once, rather than twice. 




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