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https://issues.apache.org/jira/browse/AIRFLOW-6974?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17088134#comment-17088134
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Sam T commented on AIRFLOW-6974:
--------------------------------
I think this issue happened before AIRFLOW-1452.
i used the SQL utility
([https://raw.githubusercontent.com/amachanic/sp_whoisactive/master/who_is_active.sql])
and confirmed locking issue.
!image-2020-04-20-18-14-10-275.png!
+*First Query: (session_id: 53)*+
(@P1 NVARCHAR(6),@P2 NVARCHAR(20))SELECT
[INFORMATION_SCHEMA].[TABLES].[TABLE_NAME]
FROM [INFORMATION_SCHEMA].[TABLES]
WHERE [INFORMATION_SCHEMA].[TABLES].[TABLE_SCHEMA] = CAST(@P1 AS NVARCHAR(max))
AND [INFORMATION_SCHEMA].[TABLES].[TABLE_TYPE] = CAST(@P2 AS NVARCHAR(max))
ORDER BY [INFORMATION_SCHEMA].[TABLES].[TABLE_NAME]
*+Second Query (session_id:54 , blocked by session 53)+*
(@P1 INT,@P2 NVARCHAR(24))SELECT TOP 1 slot_pool.id AS slot_pool_id,
slot_pool.pool AS slot_pool_pool, slot_pool.slots AS slot_pool_slots,
slot_pool.description AS slot_pool_description
FROM slot_pool
WHERE slot_pool.slots = @P1 AND slot_pool.pool = @P2
> Using MS SQL Server 17 as a backend, Migration
> cc1e65623dc7_add_max_tries_column_to_task_instance.py fails if load_examples
> = True
> ----------------------------------------------------------------------------------------------------------------------------------
>
> Key: AIRFLOW-6974
> URL: https://issues.apache.org/jira/browse/AIRFLOW-6974
> Project: Apache Airflow
> Issue Type: Bug
> Components: database
> Affects Versions: 1.10.9
> Reporter: Tony Brookes
> Priority: Minor
> Attachments: airflow-mssql-stack-trace.txt,
> image-2020-04-20-18-14-10-275.png
>
>
> This took me a while to figure out as there was another issue with the
> migration in question which is
> cc1e65623dc7_add_max_tries_column_to_task_instance.py
> This file USED to have an issue where it would sit there forever during an
> initdb on MS SQL Server, essentially deadlocked with itself.
> I couldn't figure out why it was still sitting there for me, given that I was
> using the version of the migration where this had been fixed, so I went
> looking at the locks on the DB. I found TWO processes running on the DB both
> originating inside the airflow initdb Python instance.
> The first was happily sitting there trying to query the max_retries column on
> a table, but the other was attempting to query the table "slot_pool" from
> within example_subdag_operator.py . I killed the session which was querying
> that table and of course my Python process crashed, helpfully with a stack
> trace.
> The session I killed was interacting with the DB running in EXAMPLES and was
> actually complaining that the table was not a valid object name. As soon as
> I set load_examples = False, the initdb process ran through in a few seconds
> and all was well. But with load_examples = True it would reliably hang on
> this specific migration every single time.
> I have attached a full stack trace from when I terminated the second DB
> session.
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