AssertionError using Apache2 and libapache2-mod-wsgi-py3 on Ubuntu 14.04 (Python 3.4)

Question

On Ubuntu 14.04, using Apache2 with package libapache2-mod-wsgi-py3 installed gives errors in /var/log/apache2/error.log

The way to reproduce is straightforward :

sudo apt-get install apache2
sudo service apache2 restart
# /var/log/apache2/error.log is "clean"
sudo apt-get install libapache2-mod-wsgi-py3
sudo service apache2 restart

/var/log/apache2/error.log gives the following error :

[Mon Jan 05 16:51:53.641332 2015] [:error] [pid 3141:tid 140703516379008] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'>
[Mon Jan 05 16:51:53.643563 2015] [:error] [pid 3141:tid 140703516379008] Traceback (most recent call last):
[Mon Jan 05 16:51:53.643633 2015] [:error] [pid 3141:tid 140703516379008]   File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown
[Mon Jan 05 16:51:53.644350 2015] [:error] [pid 3141:tid 140703516379008]     assert tlock is not None
[Mon Jan 05 16:51:53.643449 2015] [:error] [pid 3140:tid 140703516379008] Exception ignored in: <module 'threading' from '/usr/lib/python3.4/threading.py'>
[Mon Jan 05 16:51:53.644456 2015] [:error] [pid 3140:tid 140703516379008] Traceback (most recent call last):
[Mon Jan 05 16:51:53.644514 2015] [:error] [pid 3140:tid 140703516379008]   File "/usr/lib/python3.4/threading.py", line 1288, in _shutdown
[Mon Jan 05 16:51:53.645052 2015] [:error] [pid 3140:tid 140703516379008]     assert tlock is not None
[Mon Jan 05 16:51:53.645119 2015] [:error] [pid 3141:tid 140703516379008] AssertionError: 
[Mon Jan 05 16:51:53.647513 2015] [:error] [pid 3140:tid 140703516379008] AssertionError: 

How to get it work error-free?

Answer 1

Ubuntu 14.04 comes with mod_wsgi 3.4. According to https://code.djangoproject.com/ticket/22948#comment:2 we need to use mod_wsgi version 4.2+ for Python 3.4.

The best way to install mod_wsgi to the latest version is to get it with pip (can be in virtualenv) and then install its module to apache system-wide. In my case I use virtualenv set in /venv_path.

1) Remove problematic package and install dependency

sudo apt-get remove libapache2-mod-wsgi-py3
sudo apt-get install apache2-dev

2) Install mod_wsgi in virtualenv with pip

. /venv_path/bin/activate
pip install mod_wsgi

3) Install into Apache (system-wide)

sudo /venv_path/bin/mod_wsgi-express install-module
sudo vi /etc/apache2/mods-available/wsgi_express.load /etc/apache2/mods-available/wsgi_express.conf

Content of /etc/apache2/mods-available/wsgi_express.load

LoadModule wsgi_module /usr/lib/apache2/modules/mod_wsgi-py34.cpython-34m.so

Content of /etc/apache2/mods-available/wsgi_express.conf

WSGIPythonHome /venv_path

4) Enable the module and restart Apache.

sudo a2enmod wsgi_express
sudo service apache2 restart

5) Check that there are no errors in /var/log/apache2/error.log