[jira] [Created] (AIRFLOW-1008) option to prevent a dag from running concurrently

["Boris Tyukin (JIRA)" <ji...@apache.org>]

Boris Tyukin created AIRFLOW-1008:
-------------------------------------

             Summary: option to prevent a dag from running concurrently
                 Key: AIRFLOW-1008
                 URL: https://issues.apache.org/jira/browse/AIRFLOW-1008
             Project: Apache Airflow
          Issue Type: Improvement
    Affects Versions: Airflow 1.8
            Reporter: Boris Tyukin
            Priority: Minor


Would be nice to have an option to prevent a DAG from scheduling / running concurrently whether it is kicked by a scheduler or triggered externally (via airflow cli or UI).

max_active_runs only respects scheduled jobs and not the jobs ran from cli or triggered by another task.

I see this is done intentionally in dagrun_exists_dep.py:

 running_dagruns = DagRun.find(
                dag_id=dag.dag_id,
                state=State.RUNNING,
                external_trigger=False,
                session=session
            )

I've looked at depends_on_past=True but it does not really help in this case.

I am posting below some comments from Max as well:

Without looking at the latest code to confirm what I'm about to write,
`max_active_runs` really only prevents the scheduler from creating new
active DAG runs. For `max_active_runs` to apply to externally triggered
runs, we'd need to introduce handling of a new status of `scheduled` to DAG
runs. The scheduler would have to handle the new simple task of flipping
the status from this `scheduled` to `running` when `actual_active_dag_runs
< max_active_runs`. We'd probably want for the CLI command and the UI DAG
run creation process to default DAG run status to this new `scheduled`
state.

I think it should be a fairly simple feature to add in.



--
This message was sent by Atlassian JIRA
(v6.3.15#6346)