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Posted to commits@airflow.apache.org by GitBox <gi...@apache.org> on 2020/08/07 13:32:22 UTC
[GitHub] [airflow] mattinbits opened a new issue #10221: Deadlock Exception with MSSQL as backend DB
mattinbits opened a new issue #10221:
URL: https://github.com/apache/airflow/issues/10221
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**Apache Airflow version**: 1.10.9
**Kubernetes version (if you are using kubernetes)** (use `kubectl version`):
**Environment**:
- **Cloud provider or hardware configuration**: On premise infrastructure. Scheduler is a CENTOS 7 docker image running on a RHEL 7 server. Database is SQL Server 2016
- **OS** (e.g. from /etc/os-release): CentOS Linux 7 (Core)
- **Kernel** (e.g. `uname -a`): 3.10.0-1127.13.1.el7.x86_64
- **Install tools**:
- **Others**:
**What happened**:
We have a DAG where several file sensors wait for similar files in parallel, using "reschedule" mode. Periodically, one or more of these tasks fail. The logs show a deadlock reported from the Database:
```
sqlalchemy.exc.DBAPIError: (pyodbc.Error) ('40001', '[40001] [Microsoft][ODBC Driver 17 for SQL Server][SQL Server]Transaction (Process ID 111) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. (1205) (SQLExecDirectW)')
[SQL: SELECT count(*) AS count_1
FROM task_instance
WHERE task_instance.pool = ? AND task_instance.state IN (?, ?)]
[parameters: ('default_pool', 'running', 'queued')]
(Background on this error at: http://sqlalche.me/e/dbapi)
```
Checking this query directly using SSMS, I can see it executes immediately and uses the ti_pool index.
And the associated stack trace:
```
Traceback (most recent call last):
File "/usr/local/bin/airflow", line 37, in <module>
args.func(args)
File "/usr/local/lib/python3.7/site-packages/airflow/utils/cli.py", line 75, in wrapper
return f(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/airflow/bin/cli.py", line 545, in run
_run(args, dag, ti)
File "/usr/local/lib/python3.7/site-packages/airflow/bin/cli.py", line 460, in _run
run_job.run()
File "/usr/local/lib/python3.7/site-packages/airflow/jobs/base_job.py", line 221, in run
self._execute()
File "/usr/local/lib/python3.7/site-packages/airflow/jobs/local_task_job.py", line 90, in _execute
pool=self.pool):
File "/usr/local/lib/python3.7/site-packages/airflow/utils/db.py", line 74, in wrapper
return func(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 851, in _check_and_change_state_before_execution
verbose=True):
File "/usr/local/lib/python3.7/site-packages/airflow/utils/db.py", line 70, in wrapper
return func(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 644, in are_dependencies_met
session=session):
File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 668, in get_failed_dep_statuses
dep_context):
File "/usr/local/lib/python3.7/site-packages/airflow/ti_deps/deps/base_ti_dep.py", line 106, in get_dep_statuses
for dep_status in self._get_dep_statuses(ti, session, dep_context):
File "/usr/local/lib/python3.7/site-packages/airflow/ti_deps/deps/pool_slots_available_dep.py", line 62, in _get_dep_statuses
open_slots = pools[0].open_slots()
File "/usr/local/lib/python3.7/site-packages/airflow/utils/db.py", line 74, in wrapper
return func(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/airflow/models/pool.py", line 113, in open_slots
return self.slots - self.occupied_slots(session)
File "/usr/local/lib/python3.7/site-packages/airflow/utils/db.py", line 70, in wrapper
return func(*args, **kwargs)
File "/usr/local/lib/python3.7/site-packages/airflow/models/pool.py", line 70, in occupied_slots
.filter(TaskInstance.state.in_(STATES_TO_COUNT_AS_RUNNING))
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3469, in scalar
ret = self.one()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3436, in one
ret = self.one_or_none()
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3405, in one_or_none
ret = list(self)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3481, in __iter__
return self._execute_and_instances(context)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3506, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1020, in execute
return meth(self, multiparams, params)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/sql/elements.py", line 298, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1139, in _execute_clauseelement
distilled_params,
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1324, in _execute_context
e, statement, parameters, cursor, context
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1518, in _handle_dbapi_exception
sqlalchemy_exception, with_traceback=exc_info[2], from_=e
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/util/compat.py", line 178, in raise_
raise exception
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/base.py", line 1284, in _execute_context
cursor, statement, parameters, context
File "/usr/local/lib/python3.7/site-packages/sqlalchemy/engine/default.py", line 590, in do_execute
cursor.execute(statement, parameters)
```
<!-- (please include exact error messages if you can) -->
**What you expected to happen**:
The tasks succeed/reschedule as expected.
<!-- What do you think went wrong? -->
**How to reproduce it**:
I have struggled to reproduce this locally away from our production environment. I suspect it is related to the size of the task_instance table and therefore hard to reproduce locally on a clean instance of airflow.
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**Anything else we need to know**:
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[GitHub] [airflow] mik-laj commented on issue #10221: Deadlock Exception with MSSQL as backend DB
Posted by GitBox <gi...@apache.org>.
mik-laj commented on issue #10221:
URL: https://github.com/apache/airflow/issues/10221#issuecomment-701095136
MSSQL is not official supported by Airflow. See: https://github.com/apache/airflow/issues/10713
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[GitHub] [airflow] boring-cyborg[bot] commented on issue #10221: Deadlock Exception with MSSQL as backend DB
Posted by GitBox <gi...@apache.org>.
boring-cyborg[bot] commented on issue #10221:
URL: https://github.com/apache/airflow/issues/10221#issuecomment-670518366
Thanks for opening your first issue here! Be sure to follow the issue template!
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[GitHub] [airflow] potiuk closed issue #10221: Deadlock Exception with MSSQL as backend DB
Posted by GitBox <gi...@apache.org>.
potiuk closed issue #10221:
URL: https://github.com/apache/airflow/issues/10221
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