GitHub user borisovpavl73 created a discussion: Strange behavior of Local
executor
Hi!
Running airflow standalone ver 3.0.4 in WSL2 on Windows11.
With this example of code i want to watch how Airflow can control order of task
execution.
```
import pendulum
from airflow import DAG
from airflow.providers.standard.operators.python import PythonOperator
def tst_func(name):
print(f"hello from task {name}")
with DAG(
'dag_tst_tasks',
schedule='@daily',
start_date=pendulum.now().add(days=-1),
) as dag:
t1 = PythonOperator(
task_id="t1",
python_callable=tst_func,
op_kwargs={"name": 1}
)
t2 = PythonOperator(
task_id="t2",
python_callable=tst_func,
op_kwargs={"name": 2}
)
t3 = PythonOperator(
task_id="t3",
python_callable=tst_func,
op_kwargs={"name": 3}
)
t4 = PythonOperator(
task_id="t4",
python_callable=tst_func,
op_kwargs={"name": 4}
)
t5 = PythonOperator(
task_id="t5",
python_callable=tst_func,
op_kwargs={"name": 5}
)
t6 = PythonOperator(
task_id="t6",
python_callable=tst_func,
op_kwargs={"name": 6}
)
t3 >> [t4, t6, t2] >> t1
t3 >> t5
```
But for strange reasons this dag can get failed status from time to time with
error:
> Executor LocalExecutor(parallelism=32) reported that the task instance
> <TaskInstance: dag_tst_tasks.t3 manual__2025-09-09T10:57:35.672635+00:00
> [queued]> finished with state failed, but the task instance's state attribute
> is queued. Learn more:
> https://airflow.apache.org/docs/apache-airflow/stable/troubleshooting.html#task-state-changed-externally
In screenshots you may see that it can failed in first task or last
<img width="1306" height="273" alt="Снимок экрана 2025-09-09 135819"
src="https://github.com/user-attachments/assets/2884f4bc-4a7b-4cc2-b3e8-7965936d3acf";
/>
<img width="1358" height="461" alt="Снимок экрана 2025-09-09 135842"
src="https://github.com/user-attachments/assets/a92d77e4-5a69-428b-b954-f932abeb6163";
/>
If i delete parallel task execution and run tasks sequentially, all tasks
completed successfully.
Can someone explain why it is happening? Is it because i used default local
executor and standalone version?
GitHub link: https://github.com/apache/airflow/discussions/55413
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