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Posted to commits@airflow.apache.org by GitBox <gi...@apache.org> on 2021/11/28 14:29:58 UTC
[GitHub] [airflow] potiuk opened a new pull request #19862: Clarify behaviour of test_backfill_depends_on_past
potiuk opened a new pull request #19862:
URL: https://github.com/apache/airflow/pull/19862
It used to be that the backfill job deadlocked when a task had
"depends_on_past" set. This was because it depended on past,
non-existing and not succesful task.
You needed to set `ignore_first_depends_on_past' set in order to
avoid the deadlock. This test was quarantined but I think
the behaviour has changed.
It looks like currently Airflow behaves differently: when checking
dependencies, it actually retrieves the previous dag-run and
if there is none available it does not deadlock no matter if
depends_on_past is set. That makes much more sense and likely
was fixed during the recent changes involved in timetable
implementation.
This PR updates the tests to show that backfill will behave
properly, regardless from `ignore_first_depends_on_past`.
Fixes: #14755
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[GitHub] [airflow] potiuk edited a comment on pull request #19862: Clarify behaviour of test_backfill_depends_on_past
Posted by GitBox <gi...@apache.org>.
potiuk edited a comment on pull request #19862:
URL: https://github.com/apache/airflow/pull/19862#issuecomment-981097308
I am not 100% - but from what I debugged, the behaviour of backfill in case `depends_on_past==Truw` in a task have been fixed in the meantime (likely during timeteable implementation):
From what I see the backfil job will not deadlock any more but it will **just work** even if "ignore_first_depends_on_past" is set to true, simply because in prev_dagrun_dep, the prev_dagrun_dep is None (as it should be IMHO):
in https://github.com/apache/airflow/blob/846586eb86cfa927eaebbba7124e8cd34c0bebce/airflow/ti_deps/deps/prev_dagrun_dep.py#L52
No matter if catchup is True or false, previous DagRun is None (as I think it should be for backfill job).
```
if catchup:
last_dagrun = dr.get_previous_scheduled_dagrun(session)
else:
last_dagrun = dr.get_previous_dagrun(session=session)
```
However I'd love to hear other's comment if understand it right. I am not sure if there is other case where we actually still need `ignore_first_depends_on_past` in this case or should we depreacate it ?
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[GitHub] [airflow] github-actions[bot] commented on pull request #19862: Clarify behaviour of test_backfill_depends_on_past
Posted by GitBox <gi...@apache.org>.
github-actions[bot] commented on pull request #19862:
URL: https://github.com/apache/airflow/pull/19862#issuecomment-982290453
The PR most likely needs to run full matrix of tests because it modifies parts of the core of Airflow. However, committers might decide to merge it quickly and take the risk. If they don't merge it quickly - please rebase it to the latest main at your convenience, or amend the last commit of the PR, and push it with --force-with-lease.
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[GitHub] [airflow] uranusjr commented on a change in pull request #19862: Clarify behaviour of test_backfill_depends_on_past
Posted by GitBox <gi...@apache.org>.
uranusjr commented on a change in pull request #19862:
URL: https://github.com/apache/airflow/pull/19862#discussion_r758452199
##########
File path: tests/jobs/test_backfill_job.py
##########
@@ -797,25 +798,20 @@ def test_backfill_pooled_tasks(self):
ti.refresh_from_db()
assert ti.state == State.SUCCESS
- @pytest.mark.quarantined
- def test_backfill_depends_on_past(self):
- """
- Test that backfill respects ignore_depends_on_past
- """
+ @parameterized.expand([(True,), (False,)])
Review comment:
```suggestion
@pytest.mark.parametrize("ignore_depends_on_past", [True, False])
```
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[GitHub] [airflow] potiuk merged pull request #19862: Clarify behaviour of test_backfill_depends_on_past
Posted by GitBox <gi...@apache.org>.
potiuk merged pull request #19862:
URL: https://github.com/apache/airflow/pull/19862
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[GitHub] [airflow] potiuk commented on pull request #19862: Clarify behaviour of test_backfill_depends_on_past
Posted by GitBox <gi...@apache.org>.
potiuk commented on pull request #19862:
URL: https://github.com/apache/airflow/pull/19862#issuecomment-981097308
I am not 100% - but from what I debugged, the behaviour of backfill in case depends_on_past tasks have been fixed in the meantime (likely during timeteable implementation):
From what I see the backfil job will not deadlock any more but it will **just work** even if "ignore_first_depends_on_past" is set to true, simply because in prev_dagrun_dep, the prev_dagrun_dep is None (as it should be IMHO):
in https://github.com/apache/airflow/blob/846586eb86cfa927eaebbba7124e8cd34c0bebce/airflow/ti_deps/deps/prev_dagrun_dep.py#L52
No matter if catchup is True or false, previous DagRun is None (as I think it should be for backfill job).
```
if catchup:
last_dagrun = dr.get_previous_scheduled_dagrun(session)
else:
last_dagrun = dr.get_previous_dagrun(session=session)
```
However I'd love to hear other's comment if understand it right. I am not sure if there is other case where we actually still need `ignore_first_depends_on_past` in this case or should we depreacate it ?
--
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