PythonOperator with python_callable set gets executed constantly - airflow

Question

import airflow
from airflow import DAG
from airflow.operators.python_operator import PythonOperator
from datetime import datetime, timedelta
from workflow.task import some_task
default_args = {
'owner': 'airflow',
'depends_on_past': False,
'email': ['jimin.park1#aig.com'],
'email_on_failure': False,
'email_on_retry': False,
'retries': 0,
'retry_delay': timedelta(minutes=1),
'start_date': airflow.utils.dates.days_ago(0)
# 'queue': 'bash_queue',
# 'pool': 'backfill',
# 'priority_weight': 10,
# 'end_date': datetime(2016, 1, 1),
}
dag = DAG('JiminTest', default_args=default_args, schedule_interval='*/1 * * * *', catchup=False)
t1 = PythonOperator(
task_id='Task1',
provide_context=True,
python_callable=some_task,
dag=dag
)
The actual some_task itself simply appends timestamp to some file. As you can see in the dag config file, the task itself is configured to run every 1 min.
def some_task(ds, **kwargs):
current_time = datetime.datetime.now().strftime("%Y-%m-%d %H:%M:%S")
with open("test.txt", "a") as myfile:
myfile.write(current_time + '\n')
I simply tail -f the output file and started up the webserver without the scheduler running. This function was being called and things were being appended to the file when webserver starts up. When I start up the scheduler, on each execution loop, the file gets appended.
What I want is for the function to be executed on every minute as intended, not every execution loop.

Answer 1

The scheduler will run each DAG file every scheduler loop, including all import statements.
Is there anything running code in the file from where you are importing the function?

Answer 2

Try to check the scheduler_heartbeat_sec config parameter in your config file. For your case it should be smaller than 60 seconds.
If you want the scheduler not to cahtchup previous runs set catchup_by_defaultto False (I am not sure if this relevant to your question though).
Please indicate which Apache Airflow version are you using