Le blog d’Étienne Pouliot , consultant en systèmes informatiques

One of my Django installation was running fine for a few months.  Last week I had to add a new Django project to this server.

My setup was : CentOS 5.5, Apache, mod_wsgi and psycopg2 2.2.0.x

After I added the new project, I started getting random errors « can’t adapt ». It would work perfectly for a few hours than my users would start getting an annyoying 500 error.

I searched the web, this seems to be a rather common error…but everything I found was related to another issue or something that was fixed in the Django release that I’m using.

One of the first thing I tryed was to update psycoppg2 to 2.2.1.

Now I was gettinga little bit information as the error was now « can’t adapt type ‘Decimal’ ».  That’s better, but I still didn’t know how to fix it.

I ended up posting a message in the django-user mailing.

Some nice folks had exactly the same problem and told me how to fix it.  I simply had to change mod_wsgi configuration so that it would run on his own process group.

My original configuration  :

<VirtualHost *:443>
ServerName  site1.com
WSGIScriptAlias / /var/www/site1.wsgi  application-group=%{GLOBAL}
</VirtualHost>
<VirtualHost *:443>
ServerName  site2.com
WSGIScriptAlias / /var/www/site2.wsgi application-group=%{GLOBAL}
</VirtualHost>

Is now :

<VirtualHost *:443>
ServerName  site1.com
WSGIDaemonProcess site1
WSGIScriptAlias / /var/www/site1.wsgi process-group=site1 application-group=%{GLOBAL}
</VirtualHost>
<VirtualHost *:443>
ServerName  site2.com
WSGIDaemonProcess site2
WSGIScriptAlias / /var/www/site2.wsgi process-group=site2 application-group=%{GLOBAL}
</VirtualHost>

The only thing I find hard to understand is how undocumented that issue is.  I wouldn’t think that I am the only one running with that kind of setup ?