MySQL Bugs: #73232: mysql.connector.django is leaking connections

Bug #73232	mysql.connector.django is leaking connections
Submitted:	8 Jul 2014 13:29	Modified:	5 Sep 2014 13:41
Reporter:	Zemian Deng	Email Updates:
Status:	Can't repeat	Impact on me:	None
Category:	Connector / Python	Severity:	S2 (Serious)
Version:	1.2.2	OS:	Any
Assigned to:		CPU Architecture:	Any
Tags:	Django

Description:
When using "mysql.connector.django" package as database backend in a django app, it opens connection objects and does not close it properly, even if there is no traffic. This result in connection leak as soon as you start the django app!

How to repeat:
1. Create a vanilla basic django app (or just use the "mysite" from django tutorial https://docs.djangoproject.com/en/1.6/intro/tutorial01/)
2. Change the settings.py in DATABASES/default/ENGINE with "mysql.connector.django", and update NAME, USERNAME, PASSWORD etc to match to a simple database for testing.
3. Start the django app with "python manage.py runserver"
4. Login into mysql shell and monitor with "show full processlist" command. Immediately there are connection objects created even no traffic to the site.
5. Access the django app with a browser and you will see the connections in  processlist increasing.

Suggested fix:
I think this has somethign to do with DatabaseWrapper.__init__ from mysql/connector/django/base.py file (line 465).

FYI, I started a topic in forum, but no one replied. http://forums.mysql.com/read.php?50,616862,616862#msg-616862

I have a patch here that can fix the leak (see Files attachement). The problem is the DatabaseOperations is using a instance of converter from an connection object. I cached the converter in the DatabaseWrapper and then immediately close the connection after the __init__(). Then later using this "cache" converter in DatabaseOperations. So far the converter doesn't seem to need a live connection to work.

Let me know if you this works for you or not.

Path file to fix conn leak for django

Attachment: myconnpy1.2.2_django_base.py.patch (application/octet-stream, text), 1.98 KiB.

BTW, I am already an Oracle employee (zemian.deng@oracle.com), do you still need me to sign the Contributor Agreement form?

Thank you for reporting this problem.

I wasn't able to repeat it in 1.2.3
I created generic project using your link with Django 1.7 and see new connections are established in webserver console, but processlist shows the same amount of connections.

I checked base.py and it looks really different - I will close with "Can't repeat" resolution, assuming the bug was fixed by some side changes.

Hi Andrii,

Yes I can confirmed that the latest connector 1.2.3 does not have this issue any more. But previous 1.2.2 is definitely repeatable (which is what I reported against with).

Thanks for the update!
Zemian