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https://issues.apache.org/jira/browse/AIRFLOW-2145?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16560427#comment-16560427
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Abdul Nimeri commented on AIRFLOW-2145:
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I think I ran into the same issue. In my case, it was because the upstream task
moved into the `shutdown` state while it's being cleared, and then the dag run
believed it was deadlocked because:
* the only "unfinished" task is the downstream (e.g. `do_work`)
* all "unfinished" tasks don't have their dependencies met (because its
upstream isn't done)
I think the bug is that `shutdown` isn't included as an "unfinished" state (see
[https://github.com/apache/incubator-airflow/blob/c7a472ed6b0d8a4720f57ba1140c8cf665757167/airflow/utils/state.py#L110)]
and is considered a "finished" state. Which doesn't seem right considering
you'd never want a DAG be considered complete while you have an instance that's
`shutdown` (and might have some retries left)
> Deadlock after clearing a running task
> --------------------------------------
>
> Key: AIRFLOW-2145
> URL: https://issues.apache.org/jira/browse/AIRFLOW-2145
> Project: Apache Airflow
> Issue Type: Bug
> Affects Versions: 1.9.0
> Reporter: George Roldugin
> Priority: Minor
> Attachments: image-2018-02-23-18-59-11-828.png,
> image-2018-02-23-19-00-37-741.png, image-2018-02-23-19-00-55-630.png,
> image-2018-02-23-19-01-45-012.png, image-2018-02-23-19-01-57-498.png,
> image-2018-02-23-19-02-18-837.png
>
>
> TL;DR The essense of the issue is that whenever a currently running ask is
> cleared, the dagrun enters a deadlocked state and fails.
>
> We see this in production with Celery executors and {{TimeDeltaSensor}}, and
> I've been able to reproduce it locally with both {{TimeDeltaSensor}} and
> {{WebHDFSSensor}}.
> Here's the minimal example:
> {code:java}
> from datetime import datetime, timedelta
> import airflow
> from airflow.operators.sensors import TimeDeltaSensor
> from airflow.operators.dummy_operator import DummyOperator
> with airflow.DAG(
> 'foo',
> schedule_interval='@daily',
> start_date=datetime(2018, 1, 1)) as dag:
> wait_for_upstream_sla = TimeDeltaSensor(
> task_id="wait_for_upstream_sla",
> delta=timedelta(days=365*10)
> )
> do_work = DummyOperator(task_id='do_work')
> dag >> wait_for_upstream_sla >> do_work
> {code}
>
> Sequence of actions, relevant DEBUG level logs, and some UI screenshots
> {code:java}
> airflow clear foo -e 2018-02-22 --no_confirm && airflow backfill foo -s
> 2018-02-22 -e 2018-02-22{code}
> {code:java}
> [2018-02-23 17:17:45,983] {__init__.py:45} INFO - Using executor
> SequentialExecutor
> [2018-02-23 17:17:46,069] {models.py:189} INFO - Filling up the DagBag from
> /Users/grol/Drive/dev/reporting/dags
> ...
> [2018-02-23 17:17:47,563] {jobs.py:2180} DEBUG - Task instance to run
> <TaskInstance: foo.wait_for_upstream_sla 2018-02-22 00:00:00 [scheduled]>
> state scheduled
> ...
> {code}
> !image-2018-02-23-18-59-11-828.png|width=418,height=87!
> Now we clear all DAG's tasks externally:
> {code:java}
> airflow clear foo -e 2018-02-22 --no_confirm
> {code}
> This causes the following:
> {code:java}
> [2018-02-23 17:17:55,258] {base_task_runner.py:98} INFO - Subtask:
> [2018-02-23 17:17:55,258] {sensors.py:629} INFO - Checking if the time
> (2018-02-23 16:19:00) has come
> [2018-02-23 17:17:58,844] {jobs.py:184} DEBUG - [heart] Boom.
> [2018-02-23 17:18:03,848] {jobs.py:184} DEBUG - [heart] Boom.
> [2018-02-23 17:18:08,856] {jobs.py:2585} WARNING - State of this instance has
> been externally set to shutdown. Taking the poison pill.
> [2018-02-23 17:18:08,874] {helpers.py:266} DEBUG - There are no descendant
> processes to kill
> [2018-02-23 17:18:08,875] {jobs.py:184} DEBUG - [heart] Boom.
> [2018-02-23 17:18:08,900] {helpers.py:266} DEBUG - There are no descendant
> processes to kill
> [2018-02-23 17:18:08,922] {helpers.py:266} DEBUG - There are no descendant
> processes to kill
> [2018-02-23 17:18:09,005] {sequential_executor.py:47} ERROR - Failed to
> execute task Command 'airflow run foo wait_for_upstream_sla
> 2018-02-22T00:00:00 --local -sd DAGS_FOLDER/foo.py' returned non-zero exit
> status 1.
> [2018-02-23 17:18:09,012] {jobs.py:2004} DEBUG - Executor state: failed task
> <TaskInstance: foo.wait_for_upstream_sla 2018-02-22 00:00:00 [shutdown]>
> [2018-02-23 17:18:09,018] {models.py:4584} INFO - Updating state for <DagRun
> foo @ 2018-02-22 00:00:00: backfill_2018-02-22T00:00:00, externally
> triggered: False> considering 2 task(s)
> [2018-02-23 17:18:09,021] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [None]> dependency 'Previous Dagrun State' PASSED: True,
> The task did not have depends_on_past set.
> [2018-02-23 17:18:09,021] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [None]> dependency 'Not In Retry Period' PASSED: True,
> The context specified that being in a retry period was permitted.
> [2018-02-23 17:18:09,027] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [None]> dependency 'Trigger Rule' PASSED: False, Task's
> trigger rule 'all_success' requires all upstream tasks to have succeeded, but
> found 1 non-success(es). upstream_tasks_state={'skipped': 0, 'successes': 0,
> 'failed': 0, 'upstream_failed': 0, 'done': 0, 'total': 1},
> upstream_task_ids=['wait_for_upstream_sla']
> [2018-02-23 17:18:09,029] {models.py:4643} INFO - Deadlock; marking run
> <DagRun foo @ 2018-02-22 00:00:00: backfill_2018-02-22T00:00:00, externally
> triggered: False> failed
> [2018-02-23 17:18:09,045] {jobs.py:2125} INFO - [backfill progress] |
> finished run 1 of 1 | tasks waiting: 1 | succeeded: 0 | kicked_off: 1 |
> failed: 0 | skipped: 0 | deadlocked: 0 | not ready: 1
> [2018-02-23 17:18:09,045] {jobs.py:2129} DEBUG - Finished dag run loop
> iteration. Remaining tasks [<TaskInstance: foo.do_work 2018-02-22 00:00:00
> [scheduled]>]
> [2018-02-23 17:18:09,045] {jobs.py:2160} DEBUG - *** Clearing out not_ready
> list ***
> [2018-02-23 17:18:09,048] {jobs.py:2180} DEBUG - Task instance to run
> <TaskInstance: foo.do_work 2018-02-22 00:00:00 [None]> state None
> [2018-02-23 17:18:09,049] {jobs.py:2186} WARNING - FIXME: task instance {}
> state was set to None externally. This should not happen
> [2018-02-23 17:18:09,053] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [scheduled]> dependency 'Task Instance State' PASSED:
> True, Task state scheduled was valid.
> [2018-02-23 17:18:09,053] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [scheduled]> dependency 'Previous Dagrun State' PASSED:
> True, The task did not have depends_on_past set.
> [2018-02-23 17:18:09,056] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [scheduled]> dependency 'Task Concurrency' PASSED: True,
> Task concurrency is not set.
> [2018-02-23 17:18:09,056] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [scheduled]> dependency 'Not In Retry Period' PASSED:
> True, The task instance was not marked for retrying.
> [2018-02-23 17:18:09,061] {models.py:1215} DEBUG - <TaskInstance: foo.do_work
> 2018-02-22 00:00:00 [scheduled]> dependency 'Trigger Rule' PASSED: False,
> Task's trigger rule 'all_success' requires all upstream tasks to have
> succeeded, but found 1 non-success(es). upstream_tasks_state={'skipped': 0,
> 'successes': 0, 'failed': 0, 'upstream_failed': 0, 'done': 0, 'total': 1},
> upstream_task_ids=['wait_for_upstream_sla']
> [2018-02-23 17:18:09,061] {models.py:1190} INFO - Dependencies not met for
> <TaskInstance: foo.do_work 2018-02-22 00:00:00 [scheduled]>, dependency
> 'Trigger Rule' FAILED: Task's trigger rule 'all_success' requires all
> upstream tasks to have succeeded, but found 1 non-success(es).
> upstream_tasks_state={'skipped': 0, 'successes': 0, 'failed': 0,
> 'upstream_failed': 0, 'done': 0, 'total': 1},
> upstream_task_ids=['wait_for_upstream_sla']
> [2018-02-23 17:18:09,061] {jobs.py:2274} DEBUG - Adding <TaskInstance:
> foo.do_work 2018-02-22 00:00:00 [scheduled]> to not_ready
> [2018-02-23 17:18:09,067] {jobs.py:184} DEBUG - [heart] Boom.
> {code}
> !image-2018-02-23-19-00-37-741.png|width=375,height=78!
> !image-2018-02-23-19-01-57-498.png|width=374,height=77!
> Interestingly, once the success condition of the {{TimeDeltaSensor}} is met,
> in production we see the following final state in the UI: DAG failed, while
> the {{TimeDeltaSensor}} task succeeded, though there's no evidence of success
> in the celery executors logs.
> !image-2018-02-23-19-02-18-837.png|width=563,height=87!
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