MaksYermak opened a new pull request, #55778:
URL: https://github.com/apache/airflow/pull/55778
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In this PR I have added a `try-except` block for preventing the scheduler
from crashing due to `RecursionError` when making a SQL query. This error
happens when a session tries to commit a transaction with
`non-json-serializble` parameters(task-instance, dag-runs, context, etc.)
[here](https://github.com/apache/airflow/blob/v2-11-test/airflow/models/taskinstance.py#L1260).
The DAG which can reproduce this error:
```python
from airflow.models.dag import DAG
from datetime import datetime
from airflow.operators.empty import EmptyOperator
from airflow.operators.python import PythonOperator
with DAG(
dag_id="circular_conf_error",
start_date=datetime(2021, 1, 1),
schedule=None,
catchup=False,
max_active_runs=1,
default_args={"retries": 0},
description="Example of a DAG which can cause Airflow Scheduler crash.",
) as dag:
start = EmptyOperator(task_id="start")
def _create_circular_conf(**context):
context["dag_run"].conf["steps"] = context["dag_run"].conf
def _downstream_task(**context):
print("Help!")
create_circular_conf = PythonOperator(
task_id="create_circular_conf", python_callable=_create_circular_conf
)
downstream_task = PythonOperator(
task_id="downstream_task", python_callable=_downstream_task
)
end = EmptyOperator(task_id="end")
# Define task dependencies
start >> create_circular_conf >> downstream_task >> end
# If you run the create_circular_conf task without a real downstream task
# (note that the "end" task is an EmptyOperator which doesn't actually
get run)
# then the scheduler doesn't run into infinite sigterm loop.
# start >> create_circular_conf >> end
```
This problem doesn't exist for AF3. Because for AF3 the code
[raise](https://github.com/apache/airflow/blob/main/task-sdk/src/airflow/sdk/definitions/param.py#L68C1-L72C1)
exception and failed immediately in place where discover the
`non-json-serializable` data. In the AF2 the code
[shows](https://github.com/apache/airflow/blob/v2-11-test/airflow/models/param.py#L74C1-L82C1)
the warning that using `non-json-serializable` parameters will be deprecated
in AF3. It does not prevent airflow from crashing later with more dramatic
consequences.
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