xchwan opened a new pull request, #75708:
URL: https://github.com/apache/airflow/pull/75708
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---
An alert that calls `session.rollback()` while the scheduler creates a Dag
run (for example a custom deadline reference that rolls back on a database
error) discards the pending DagRun. `_process_dagrun_deadline_alerts` kept
going, so a later alert such as `FIXED_DATETIME` added a Deadline for the
missing run, violated `deadline_dagrun_id_fkey` and crashed the scheduler on
every restart. With no later alert, `create_dagrun` returned the discarded run
and the scheduler treated it as created.
The loop now checks after each alert that the DagRun is still in the session
and raises `DagRunRolledBackError` if not. The scheduler's existing `Failed
creating DagRun` handler logs it, `next_dagrun` is not advanced, and other Dags
keep scheduling.
This changes behavior: `create_dagrun` now raises instead of returning the
discarded run, and
`test_dagrun_deadline_failure_that_detaches_orm_objects_still_skips` is updated
to match.
It does not make the run creatable when an alert always rolls back, so that
Dag still gets no runs, but it now fails visibly. The run cannot be protected
inside this function: commits are rejected by `CommitProhibitorGuard`, and
`session.rollback()` inside a savepoint still rolls back the outermost
transaction.
Verified with the plugin and Dag from the issue on Breeze with Postgres and
the real scheduler: on main the scheduler exits with 4 foreign key errors; with
this PR it keeps running and logs `Failed creating DagRun`.
closes: #74677
---
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