[GitHub] [airflow] imsharadmishra removed a comment on issue #9975: max_active_runs = 1 can still create multiple active execution runs

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

imsharadmishra removed a comment on issue #9975:
URL: https://github.com/apache/airflow/issues/9975#issuecomment-812917371


   I had the same issue with airflow 2.0.1. 
   I was able to fix it following combinations of parameter.
   AIRFLOW__CORE__MAX_ACTIVE_RUNS_PER_DAG -> 16 (default value)
   max_active_runs=1 inside the dag.
   Trick here I used it to pass this parameter inside DAG constructor instead of default_args argument.
   
   Here is an example:
   
   ```from airflow import DAG
   from airflow.providers.mysql.operators.mysql import MySqlOperator
   from airflow.utils.dates import days_ago
   from airflow.sensors.sql_sensor import SqlSensor
   from airflow.operators.bash import BashOperator
   from datetime import datetime, timedelta
   from airflow.hooks.base_hook import BaseHook
   from airflow.contrib.operators.slack_webhook_operator import SlackWebhookOperator
   
   
   default_args = {
       'owner': 'airflow',
       'start_date': datetime(2021, 3, 31, 14, 00)
   }
   
   dag = DAG(
       'example_sensor',
       default_args=default_args,
       tags=['mysql', 'sensor'],
       schedule_interval='*/3 * * * *',
       catchup=False,
       max_active_runs=1
   )
   
   check_slices_sql_sensor_task = SqlSensor(
       task_id='check_slices', 
       conn_id='mysql_novus', 
       sql=r"""SELECT * FROM slices;""", 
       poke_interval=30, timeout=60,
       dag=dag
   )
   
   
   
   print_slices = BashOperator(
       task_id='print_slices',
       bash_command='sleep 480',
       dag=dag
   )
   check_slices_sql_sensor_task >> print_slices
   ```


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