The cache is a very important part of your Symfony application as it helps your web server to perform better by not executing unnecessary code on every request, this is especially true if your server is running with limited resources. Cache warming allows you to cache specific data in your application through the use of a CacheWarmer. Symfony 2 includes a cache warmer that helps you to store parts of your application in cache, before the application becomes available to the user.

He shows how to create the "warmup" in an object extending the CacheWarmer to pull in content (in his case, just a text string) and write it out to a cache file automatically. Also included is the config updates you'll need to make to tell the Service Container about the Warmer.