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From "Daniel Huang (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (AIRFLOW-1559) MySQL warnings about aborted connections, missing engine disposal
Date Wed, 08 Nov 2017 22:05:00 GMT

     [ https://issues.apache.org/jira/browse/AIRFLOW-1559?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Daniel Huang reassigned AIRFLOW-1559:
-------------------------------------

    Assignee: Daniel Huang

> MySQL warnings about aborted connections, missing engine disposal
> -----------------------------------------------------------------
>
>                 Key: AIRFLOW-1559
>                 URL: https://issues.apache.org/jira/browse/AIRFLOW-1559
>             Project: Apache Airflow
>          Issue Type: Bug
>          Components: db
>            Reporter: Daniel Huang
>            Assignee: Daniel Huang
>            Priority: Minor
>
> We're seeing a flood of warnings about aborted connections in our MySQL logs. 
> {code}
> Aborted connection 56720 to db: 'airflow' user: 'foo' host: 'x.x.x.x' (Got an error reading
communication packets)
> {code}
> It appears this is because we're not performing [engine disposal|http://docs.sqlalchemy.org/en/latest/core/connections.html#engine-disposal].
The most common source of this warning is from the scheduler, when it kicks off new processes
to process the DAG files. Calling dispose in https://github.com/apache/incubator-airflow/blob/master/airflow/jobs.py#L403
greatly reduced these messages. However, the worker is still causing some of these, I assume
from when we spin up processes to run tasks. We do call dispose in https://github.com/apache/incubator-airflow/blob/master/airflow/models.py#L1394-L1396,
but I think it's a bit early. Not sure if there's a place we can put this cleanup to ensure
it's done everywhere.
> Quick script to reproduce this warning message:
> {code}
> from airflow import settings
> from airflow.models import Connection
> session = settings.Session()
> session.query(Connection).count()
> session.close()
> # not calling settings.engine.dispose()
> {code}
> Reproduced with Airflow 1.8.1, MySQL 5.7, and SQLAlchemy 1.1.13. 



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