[GitHub] [airflow] ephraimbuddy commented on a change in pull request #21362: Avoid deadlock when rescheduling task

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

ephraimbuddy commented on a change in pull request #21362:
URL: https://github.com/apache/airflow/pull/21362#discussion_r800809192



##########
File path: airflow/models/taskinstance.py
##########
@@ -1671,11 +1671,24 @@ def _handle_reschedule(
         # Don't record reschedule request in test mode
         if test_mode:
             return
+
+        from airflow.models.dagrun import DagRun  # Avoid circular import
+
         self.refresh_from_db(session)
 
         self.end_date = timezone.utcnow()
         self.set_duration()
 
+        # Lock DAG run to be sure not to get into a deadlock situation when trying to insert
+        # TaskReschedule which apparently also creates lock on corresponding DagRun entity
+        with_row_locks(
+            session.query(DagRun).filter_by(
+                dag_id=self.dag_id,
+                run_id=self.run_id,
+            ),
+            session=session,
+        ).one()

Review comment:
       Does it look like this will throw an error if we can't obtain a lock?




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