manipatnam opened a new pull request, #64162:
URL: https://github.com/apache/airflow/pull/64162
<!-- SPDX-License-Identifier: Apache-2.0
https://www.apache.org/licenses/LICENSE-2.0 -->
Fix `CronTriggerTimetable` ignoring `run_immediately` when `start_date` is
set, simplify its
semantics, and document the parameter properly.
**Bug:** `run_immediately` was only respected on the very first run when
`start_date=None`.
When `start_date` was set (the common case), `_calc_first_run()` was skipped
and the
timetable always fell back to `align_to_prev(now)`, behaving as
`run_immediately=True`
regardless of the value passed. The fix ensures `_calc_first_run()` is
always called on
the first run, whether or not `start_date` is set.
**Semantic fix:** `run_immediately=False` previously applied an undocumented
auto-buffer window
(10 % of the cron interval, minimum 5 min) identical to `None`, making
`False` not mean what
users expected. `False` now cleanly means "always skip the past cron point
and wait for the
next future one".
**Backward compatibility:** The default is changed from `False` to `True` so
that existing DAGs
without an explicit `run_immediately` continue to run the most recent past
cron point immediately,
preserving the original behaviour of `CronTriggerTimetable`.
**Changes:**
- `_TriggerTimetable.next_dagrun_info`: on first run (`no prior runs`),
always call
`_calc_first_run()` regardless of `start_date`; after a pause/resume keep
the existing
"pick most recent past boundary" logic unchanged
- `CronTriggerTimetable._calc_first_run`: simplified to three clean cases —
`True` (run past), `False` (wait for next), `timedelta` (run past if
within window)
- Default `run_immediately` changed `False → True` in `CronTriggerTimetable`,
`MultipleCronTriggerTimetable`, and `CronPartitionTimetable`
- Docs: added full `run_immediately` documentation with examples and
`versionadded:: 3.0.0`
- Docs: corrected the paused-then-unpaused example (both timetables skip
only Feb 1 and
immediately trigger Feb 2 — the claim that `CronTriggerTimetable` skips
Feb 2 as well was wrong)
- Tests: updated existing tests and added
`test_run_immediately_false_with_start_date`,
`test_run_immediately_true_with_start_date`,
`test_run_immediately_false_after_unpause`
---
##### Was generative AI tooling used to co-author this PR?
- [X] Yes — Claude Sonnet 4.6
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