[GitHub] [airflow] nathadfield commented on issue #9975: max_active_runs = 1 can still create multiple active execution runs

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

nathadfield commented on issue #9975:
URL: https://github.com/apache/airflow/issues/9975#issuecomment-749490281


   For what it's worth, this doesn't seem to be an issue on `master` but it certainly is on 2.0 installed from pip.
   
   I created this DAG, switched it on and allowed it to catchup and then cleared the status of all tasks.
   
   ```
   from airflow import models
   from airflow.operators.bash import BashOperator
   from datetime import datetime, timedelta
   
   default_args = {
       'owner': 'airflow',
       'start_date': datetime(2020, 12, 10),
       'retries': 3,
       'retry_delay': timedelta(minutes=5),
   }
   
   dag_name = 'test_dag'
   
   with models.DAG(dag_name,
                   default_args=default_args,
                   schedule_interval='0 0 * * *',
                   catchup=True,
                   max_active_runs=1
                   ) as dag:
   
       start = BashOperator(
           task_id=f'start',
           bash_command='echo "Starting"; echo "Sleeping for 30 seconds"; sleep 30; echo "Finished"'
       )
   ```
   As you can see, all the tasks are now running at the same time.
   
   <img width="1181" alt="Screenshot 2020-12-22 at 11 16 44" src="https://user-images.githubusercontent.com/967119/102883022-38213800-4447-11eb-9724-2e58f8e705e6.png">
   
   
   


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