TL;DR: Small app that performs purge requests on a set of URLs.
Often, flushing a large set of urls requires either to restart varnish (thus destroying all those precious pages already in cache) or to perform a lot of queries of a large set of urls
Install the required packages thanks to composer (https://getcomposer.org). You need to have a RabbitMQ server up and running.
curl -sS https://getcomposer.org/installer | php
php composer.phar install
Then, start a server
./console listen
Now, you can start sending urls to the flusher thanks to
./console flush filename
where filename is the location of a file containing the urls that you want to flush, one url on each line.
If you wannt to know how many urls still remain in the queue and have to be flushed, just run :
./console status