Task duration keeps increasing for skipped tasks due to DAG timeout

^{Originally posted by **Szjs-z** July 29, 2025}
Hi Airflow community,

I've encountered an issue where task duration keeps increasing for tasks that are skipped due to DAG timeout:

**Problem Description:**
When a DAG run times out due to `dagrun_timeout`, the unfinished tasks are marked as `SKIPPED`. However, in the Web UI, the task duration continues to increase even though the task state is `SKIPPED` :

**Root Cause Analysis:**
From code inspection in `airflow/jobs/scheduler_job.py`, the `_schedule_dag_run` method handles DAG timeout by:

```python
if (
dag_run.start_date
and dag.dagrun_timeout
and dag_run.start_date < timezone.utcnow() - dag.dagrun_timeout
):
dag_run.set_state(DagRunState.FAILED)
unfinished_task_instances = session.scalars(
select(TI)
.where(TI.dag_id == dag_run.dag_id)
.where(TI.run_id == dag_run.run_id)
.where(TI.state.in_(State.unfinished))
)
for task_instance in unfinished_task_instances:
task_instance.state = TaskInstanceState.SKIPPED
session.merge(task_instance)
session.flush()
self.log.info("Run %s of %s has timed-out", dag_run.run_id, dag_run.dag_id)

```

1. Setting DAG run state to FAILED
2. Marking unfinished tasks as SKIPPED
3. But it doesn't set `end_date` for these task instances

I'm wondering if this is a known issue or if there's a recommended way to handle this.

Thanks,
Chris Zhao