NihalRadhakrishna opened a new pull request, #71765:
URL: https://github.com/apache/airflow/pull/71765
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### 1. Problem
Pausing a Dag stopped the scheduler from examining already-running Dag runs
and from enqueueing remaining `scheduled` tasks. In-flight work froze until
unpaused, even though running tasks were allowed to finish. As a result,
a running Dag could remain running indefinitely because its downstream tasks
would never be queued.
closes: #71381
### 2. Solution
- A Dag run that is already running continues while the Dag is paused:
remaining tasks are still scheduled and queued, and the run can reach a
terminal state.
- Queued Dag runs stay queued until unpause.
- New Dag runs are not created.
- Pause is not the way to stop in-flight work. If you need a running Dag run
to stop, mark the run or its tasks as failed.
### Cleanup
- Removed `_update_dag_run_state_for_paused_dags` (and its 60s timer).
Paused running Dag runs are now examined in the main scheduler loop, so a
separate `update_state` pass was redundant.
### Tests
```bash
uv run --project airflow-core pytest \
airflow-core/tests/unit/models/test_dagrun.py::TestDagRun::test_next_dagruns_to_examine_paused
\
airflow-core/tests/unit/jobs/test_scheduler_job.py::TestSchedulerJob::test_execute_task_instances_paused_running_dag_still_enqueues
\
airflow-core/tests/unit/jobs/test_scheduler_job.py::TestSchedulerJob::test_paused_running_dag_run_reaches_terminal_state
\
airflow-core/tests/unit/jobs/test_scheduler_job.py::TestSchedulerJob::test_paused_running_dag_still_schedules_and_enqueues_downstream
\
airflow-core/tests/unit/jobs/test_scheduler_job.py::TestSchedulerJob::test_paused_queued_dag_run_stays_queued_until_unpause
\
-xvs
```
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##### Was generative AI tooling used to co-author this PR?
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