(2006, 'MySQL server has gone away') in django1.6 when wait_timeout passed

[ekeydar@…]

In django 1.6, when the wait_timeout passed (of mysql), then DB access cause the (2006, 'MySQL server has gone away') error.
This was not the case in django 1.5.1

I've noticed this error when using workers that run the django code (using gearman).

To reproduce:

Set the timeout to low value by editing /etc/mysql/my.cnf
add the following under [mysqld]

wait_timeout = 10
interactive_timeout = 10

Then

% python manage.py shell

>>> # access DB 
>>> import django.contrib.auth.models
>>> print list(django.contrib.auth.models.User.objects.all())
>>> import time
>>> time.sleep(15)
>>> print list(django.contrib.auth.models.User.objects.all())

Now you get the error.

Simple solution I found on the web is to call django.db.close_connection() before the access

>>> import django.db
>>> django.db.close_connection()
>>> print list(django.contrib.auth.models.User.objects.all())

works ok.

[Aymeric Augustin]

Are you using persistent connections (CONN_MAX_AGE > 0)?

[ekeydar@…]

Not using this.

[Aymeric Augustin]

This might be a side effect of using autocommit. Since Django 1.5 kept a transaction open in that case, MySQL couldn't close the connection. Now it can.

Could you try the following snippet to confirm my hypothesis?

>>> import django.contrib.auth.models
>>> from django.db import transaction
>>> with transaction.atomic():
...     print list(django.contrib.auth.models.User.objects.all())
...     import time
...     time.sleep(15)
...     print list(django.contrib.auth.models.User.objects.all())

You shouldn't get a timeout when you run this on Django 1.6.