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https://issues.apache.org/jira/browse/AIRFLOW-4881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16877151#comment-16877151
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ASF GitHub Bot commented on AIRFLOW-4881:
-----------------------------------------
tamasflamich commented on pull request #5514: [AIRFLOW-4881] Persist the
max_tries field of task instances during zombie collection
URL: https://github.com/apache/airflow/pull/5514
Make sure you have checked _all_ steps below.
### Jira
- [ ] My PR addresses the following [Airflow
Jira](https://issues.apache.org/jira/browse/AIRFLOW-4881) issues and references
them in the PR title.
- https://issues.apache.org/jira/browse/AIRFLOW-4881
### Description
- [ ] Here are some details about my PR, including screenshots of any UI
changes:
In case a task instance
- has more attempts than retries (it can happen when the state of the task
instance is explicitly cleared) and
- task instance is prematurely terminated (without graceful shutdown)
then zombie collection process of the scheduler can mark the task instance
failed instead of up_for_retry.
This happens because the `max_retries` field is not persisted but set to its
initial value (`retries`).
### Tests
- [ ] My PR adds the following unit tests __OR__ does not need testing for
this extremely good reason:
### Commits
- [ ] My commits all reference Jira issues in their subject lines, and I
have squashed multiple commits if they address the same issue. In addition, my
commits follow the guidelines from "[How to write a good git commit
message](http://chris.beams.io/posts/git-commit/)":
1. Subject is separated from body by a blank line
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1. Subject uses the imperative mood ("add", not "adding")
1. Body wraps at 72 characters
1. Body explains "what" and "why", not "how"
### Documentation
- [ ] In case of new functionality, my PR adds documentation that describes
how to use it.
- All the public functions and the classes in the PR contain docstrings
that explain what it does
- If you implement backwards incompatible changes, please leave a note in
the [Updating.md](https://github.com/apache/airflow/blob/master/UPDATING.md) so
we can assign it to a appropriate release
### Code Quality
- [ ] Passes `flake8`
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> Zombie collection fails task instances that should be scheduled for retry
> -------------------------------------------------------------------------
>
> Key: AIRFLOW-4881
> URL: https://issues.apache.org/jira/browse/AIRFLOW-4881
> Project: Apache Airflow
> Issue Type: Bug
> Components: scheduler
> Affects Versions: 1.10.3
> Reporter: Tamas Flamich
> Priority: Major
>
> In case a task instance
> * has more attempts than retries (it can happen when the state of the task
> instance is explicitly cleared) and
> * task instance is prematurely terminated (without graceful shutdown)
> then zombie collection process of the scheduler can mark the task instance
> failed instead of retrying it.
> Steps to reproduce:
> 1 - The task is scheduled for a particular executed date and the following
> records gets created in the database.
> ||task_id||retries||try_number||max_tries||state||
> |emr_sensor|2|1|2|running|
> 2 - The job owners would like to schedule the task again therefore they clear
> that state of the task instance. {{try_number}} and {{max_retries}} gets
> updated.
> ||task_id||retries||try_number||max_tries||state||
> |emr_sensor|2|2|3|running|
> 3 - The Airlflow scheduler gets killed and a new scheduler instance starts
> looking for zombie tasks. Since {{try_number < max_tries}}, the new state is
> {{up_for_retry}}. However, there is a bug in the [state update
> logic|https://github.com/apache/airflow/blob/d5a5b9d9f1f1efb67ffed4d8e6ef3e0a06467bed/airflow/models/dagbag.py#L295]
> that will revert the {{max_tries}} value to the initial value ({{retries}}).
> ||task_id||retries||try_number||max_tries||state||
> |emr_sensor|2|2|2|up_for_retry|
> 4 - During the next iteration of the scheduler, the task instance gets picked
> up. However, since {{try_number >= max_tries}}, the new state is {{failed}}.
> ||task_id||retries||try_number||max_tries||state||
> |emr_sensor|2|2|2|failed|
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