[jira] [Commented] (AIRFLOW-6043) `Dag.sub_dag` method keeps references to origin dag

["ASF GitHub Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/AIRFLOW-6043?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16980162#comment-16980162 ] 

ASF GitHub Bot commented on AIRFLOW-6043:
-----------------------------------------

Khrol commented on pull request #6638: [AIRFLOW-6043] Update dag reference to all tasks in sub_dag
URL: https://github.com/apache/airflow/pull/6638
 
 
   Graph UI is broken when tasks are filtered by root if
   root is in the middle of chain of tasks.
   
   The initial of the problem is in `sub_dag` method that keeps references
   to the original DAG. `deepcopy` call is optimized and the optimization is
   not 100% correct.
   
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> `Dag.sub_dag` method keeps references to origin dag
> ---------------------------------------------------
>
>                 Key: AIRFLOW-6043
>                 URL: https://issues.apache.org/jira/browse/AIRFLOW-6043
>             Project: Apache Airflow
>          Issue Type: Bug
>          Components: core, DAG
>    Affects Versions: 1.10.6
>            Reporter: Igor Khrol
>            Assignee: Igor Khrol
>            Priority: Major
>
> ```
> t1 = DummyOperator(task_id="t1", dag=DAG)
> t2 = DummyOperator(task_id="t2", dag=DAG)
> t3 = DummyOperator(task_id="t3", dag=DAG)
> t1 >> t2
> t2 >> t3
> ```
> Graph view is broken for such DAG if `root=t2`.
> The root cause of the problem is with `sub_dag` method. `t2` task of subdag when taken from `t1` still has a reference to `t3`.



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