[
https://issues.apache.org/jira/browse/AIRFLOW-2516?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17006357#comment-17006357
]
ASF GitHub Bot commented on AIRFLOW-2516:
-----------------------------------------
potiuk commented on pull request #6988: [AIRFLOW-2516] Fix mysql deadlocks
URL: https://github.com/apache/airflow/pull/6988
Deadlocks were occuring in mysql when task_instance was modified
by two queries at the same time. One query used state as selection
criteria and updated it in the same query where second query just
updated the state for the same table. The first query locked state
index first and primary index afterwards, the second query locked
primary index first and state afterwards - leading to deadlocks.
This change splits the first query into two independent ones.
First query makes select FOR UPDATE and selects all the task
instances to act on (this will lock primary index only)
and second updates all affected task instances.
Note that performance impact for that is neglectable because this
query is only run once every scheduler loop and the second part
of it (looping through task instances) will only happen in case
there are some manually modified DagRun states - so it is only
run to correct some wrong states of DagRun. This should happen
very infrequently.
- [x] Description above provides context of the change
- [x] Commit message contains
[\[AIRFLOW-XXXX\]](https://issues.apache.org/jira/browse/AIRFLOW-XXXX) or
`[AIRFLOW-XXXX]` for document-only changes
- [x] Unit tests coverage for changes (not needed for documentation changes)
- [x] Commits follow "[How to write a good git commit
message](http://chris.beams.io/posts/git-commit/)"
- [x] Relevant documentation is updated including usage instructions.
- [x] I will engage committers as explained in [Contribution Workflow
Example](https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst#contribution-workflow-example).
In case of fundamental code change, Airflow Improvement Proposal
([AIP](https://cwiki.apache.org/confluence/display/AIRFLOW/Airflow+Improvements+Proposals))
is needed.
In case of a new dependency, check compliance with the [ASF 3rd Party
License Policy](https://www.apache.org/legal/resolved.html#category-x).
In case of backwards incompatible changes please leave a note in
[UPDATING.md](https://github.com/apache/airflow/blob/master/UPDATING.md).
Read the [Pull Request
Guidelines](https://github.com/apache/airflow/blob/master/CONTRIBUTING.rst#pull-request-guidelines)
for more information.
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> Deadlock found when trying to update task_instance table
> --------------------------------------------------------
>
> Key: AIRFLOW-2516
> URL: https://issues.apache.org/jira/browse/AIRFLOW-2516
> Project: Apache Airflow
> Issue Type: Bug
> Components: DagRun
> Affects Versions: 1.8.0
> Reporter: Jeff Liu
> Priority: Major
> Attachments: Screenshot 2019-12-30 at 10.42.52.png,
> image-2019-12-30-10-48-41-313.png, image-2019-12-30-10-58-02-610.png, jobs.py
>
>
>
>
> {code:java}
> [2018-05-23 17:59:57,218] {base_task_runner.py:98} INFO - Subtask:
> [2018-05-23 17:59:57,217] {base_executor.py:49} INFO - Adding to queue:
> airflow run production_wipeout_wipe_manager.Carat Carat_20180227
> 2018-05-23T17:41:18.815809 --local -sd DAGS_FOLDER/wipeout/wipeout.py
> [2018-05-23 17:59:57,231] {base_task_runner.py:98} INFO - Subtask: Traceback
> (most recent call last):
> [2018-05-23 17:59:57,232] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/bin/airflow", line 27, in <module>
> [2018-05-23 17:59:57,232] {base_task_runner.py:98} INFO - Subtask:
> args.func(args)
> [2018-05-23 17:59:57,232] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/airflow/bin/cli.py", line 392, in run
> [2018-05-23 17:59:57,232] {base_task_runner.py:98} INFO - Subtask:
> pool=args.pool,
> [2018-05-23 17:59:57,233] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/airflow/utils/db.py", line 50, in
> wrapper
> [2018-05-23 17:59:57,233] {base_task_runner.py:98} INFO - Subtask: result =
> func(*args, **kwargs)
> [2018-05-23 17:59:57,233] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/airflow/models.py", line 1532, in
> _run_raw_task
> [2018-05-23 17:59:57,234] {base_task_runner.py:98} INFO - Subtask:
> self.handle_failure(e, test_mode, context)
> [2018-05-23 17:59:57,234] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/airflow/models.py", line 1641, in
> handle_failure
> [2018-05-23 17:59:57,234] {base_task_runner.py:98} INFO - Subtask:
> session.merge(self)
> [2018-05-23 17:59:57,235] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line
> 1920, in merge
> [2018-05-23 17:59:57,235] {base_task_runner.py:98} INFO - Subtask:
> _resolve_conflict_map=_resolve_conflict_map)
> [2018-05-23 17:59:57,235] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line
> 1974, in _merge
> [2018-05-23 17:59:57,236] {base_task_runner.py:98} INFO - Subtask: merged =
> self.query(mapper.class_).get(key[1])
> [2018-05-23 17:59:57,236] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 882,
> in get
> [2018-05-23 17:59:57,236] {base_task_runner.py:98} INFO - Subtask: ident,
> loading.load_on_pk_identity)
> [2018-05-23 17:59:57,236] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 952,
> in _get_impl
> [2018-05-23 17:59:57,237] {base_task_runner.py:98} INFO - Subtask: return
> db_load_fn(self, primary_key_identity)
> [2018-05-23 17:59:57,237] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/loading.py", line 247,
> in load_on_pk_i
> dentity
> [2018-05-23 17:59:57,237] {base_task_runner.py:98} INFO - Subtask: return
> q.one()
> [2018-05-23 17:59:57,238] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2884,
> in one
> [2018-05-23 17:59:57,238] {base_task_runner.py:98} INFO - Subtask: ret =
> self.one_or_none()
> [2018-05-23 17:59:57,238] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2854,
> in one_or_none
> [2018-05-23 17:59:57,238] {base_task_runner.py:98} INFO - Subtask: ret =
> list(self)
> [2018-05-23 17:59:57,239] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2925,
> in __iter__
> [2018-05-23 17:59:57,239] {base_task_runner.py:98} INFO - Subtask: return
> self._execute_and_instances(context)
> [2018-05-23 17:59:57,239] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2946,
> in _execute_and_instances
> [2018-05-23 17:59:57,240] {base_task_runner.py:98} INFO - Subtask:
> close_with_result=True)
> [2018-05-23 17:59:57,240] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2955,
> in _get_bind_ar
> s
> [2018-05-23 17:59:57,240] {base_task_runner.py:98} INFO - Subtask: **kw
> [2018-05-23 17:59:57,240] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2937,
> in _connection_f
> rom_session
> [2018-05-23 17:59:57,241] {base_task_runner.py:98} INFO - Subtask: conn =
> self.session.connection(**kw)
> [2018-05-23 17:59:57,241] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line
> 1035, in connection
> [2018-05-23 17:59:57,241] {base_task_runner.py:98} INFO - Subtask:
> execution_options=execution_options)
> [2018-05-23 17:59:57,241] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line
> 1040, in _connection
> _for_bind
> [2018-05-23 17:59:57,242] {base_task_runner.py:98} INFO - Subtask: engine,
> execution_options)
> [2018-05-23 17:59:57,242] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 388,
> in _connection_
> for_bind
> [2018-05-23 17:59:57,242] {base_task_runner.py:98} INFO - Subtask:
> self._assert_active()
> [2018-05-23 17:59:57,243] {base_task_runner.py:98} INFO - Subtask: File
> "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/session.py", line 276,
> in _assert_acti
> ve
> [2018-05-23 17:59:57,243] {base_task_runner.py:98} INFO - Subtask: %
> self._rollback_exception
> [2018-05-23 17:59:57,244] {base_task_runner.py:98} INFO - Subtask:
> sqlalchemy.exc.InvalidRequestError: This Session's transaction has been
> rolled back due to a previou
> s exception during flush. To begin a new transaction with this Session, first
> issue Session.rollback(). Original exception was:
> (_mysql_exceptions.OperationalError) (1
> 213, 'Deadlock found when trying to get lock; try restarting transaction')
> [SQL: u'UPDATE task_instance SET state=%s WHERE task_instance.task_id = %s
> AND task_instance
> .dag_id = %s AND task_instance.execution_date = %s'] [parameters: (u'queued',
> 'Carat_20180227', 'production_wipeout_wipe_manager.Carat',
> datetime.datetime(2018, 5, 23,
> 17, 41, 18, 815809))] (Background on this error at:
> http://sqlalche.me/e/e3q8){code}
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