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Would an automatic transform of mysql:// to mysql+pymysql:// be possible? Is there any reason to not have pymysql?

Tim

From: Arne Wiebalck <Arne.Wiebalck at cern.ch>
Date: Tuesday, 23 May 2017 at 17:50
To: Sean McGinnis <sean.mcginnis at gmx.com>
Cc: openstack-operators <openstack-operators at lists.openstack.org>
Subject: Re: [Openstack-operators] DB deadlocks due to connection string

As discussed on the Cinder channel, I’ve opened

https://bugs.launchpad.net/oslo.db/+bug/1692956

to see if oslo.db would be a good place to produce a warning when it detects
this potential misconfiguration.

Cheers,
 Arne

On 23 May 2017, at 17:25, Sean McGinnis <sean.mcginnis at gmx.com<mailto:sean.mcginnis at gmx.com>> wrote:

Just wanted to put this out there to hopefully spread awareness and
prevent it from happening more.

We had a bug reported in Cinder of hitting a deadlock when attempting
to deelte multiple volumes simultaneously:

https://bugs.launchpad.net/cinder/+bug/1685818

Some were seeing it, but others were not able to reproduce the error
in their environments.

What it came down to is the use of "mysql://" vs "mysql+pymysql://"
for the database connection string. Big thanks to Gerhard Muntingh
for noticing this difference.

Basically, when using "mysql://" for the connection string, that uses
blocking calls that prevent other "threads" from running at the same
time, causing these deadlocks.

This doesn't just impact Cinder, so I wanted to get the word out that
it may be worth checking your configurations and make sure you are
using "mysql+pymysql://" for your connections.

Sean


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--
Arne Wiebalck
CERN IT


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