Once you have XTools up and running, depending on how much traffic you receive, you might want to implement measures to ensure stability.
6.1. Rate limiting¶
Rate limiting can safeguard against spider crawls and bots that overload the application.
To configure, set the following variables in
10is the number of minutes
app.rate_limit_countrequests from the same user to the same URI are allowed.
5is the number of requests from the same user that are allowed during the time frame specified by
Using the above example, if you try to load the same page more than 5 times within 10 minutes, the request will be denied and you will have to wait 10 minutes before you can make the same request. This only applies to result pages and the API, and not index pages. Additionally, no rate limitations are imposed if the user is authenticated.
Any requests that are denied are logged at
You can blacklist user agents and URIs using the request_blacklist.yml file.
6.2. Offloading API requests¶
XTools features a rich public API. In addition, the internal API used for the Edit Counter can be very expensive in terms of resources. If you expect your XTools installation will receive a lot of traffic, you might consider setting up a dedicated API server so that resources on the main app server are not hogged.
This documentation covers how to set up forwarding so that all requests to /api go to the API server, assuming you are using Apache in a Linux environment.
- Install libapache2-mod-proxy-html and libxml2-dev:
sudo apt-get install libapache2-mod-proxy-html libxml2-dev
- Enable the necessary modules (if some are already enabled it will simply make sure they are active):
sudo a2enmod proxy sudo a2enmod proxy_http sudo a2enmod proxy_ajp sudo a2enmod rewrite sudo a2enmod deflate sudo a2enmod headers sudo a2enmod proxy_balancer sudo a2enmod proxy_connect sudo a2enmod proxy_html sudo a2enmod xml2enc
- In your Apache coniguration, within the
<VirtualHost>block, add this to the bottom:
ProxyPreserveHost On ProxyPass /api http://X.X.X.X:80/app.php/api ProxyPassReverse /api http://X.X.X.X:80/app.php/api
X.X.X.Xwith the IP of the API server.
- Finally, restart apache with
sudo apachectl -k graceful
6.3. Killing slow queries¶
This is not necessary for installations with MySQL-like support for max_connection_time, such as the Wikimedia replicas.
Some queries on users with a high edit count may take a very long time to finish or even timout. You may wish to add a query killer to ensure stability.
If you are running on a Linux environment, consider using pt-kill. A query killer daemon could be configured like so:
pt-kill --user=xxxx --password=xxxx --host=xxxx \ --busy-time=90 \ --log /var/www/web/killed_slow_queries.txt \ --match-info "^(select|SELECT|Select)" \ --kill --print --daemonize --verbose
This will kill any SELECT query that takes over 90 seconds to finish, and log the query at
Note that pt-kill requires libdbi-perl and libdbd-mysql-perl.