A few weeks ago I was surprised by a PHP out-of-memory error in the production environment for one of my symfony 1.2 powered sites. This error was being thrown by sfViewCacheManager, the class responsible for deciding whether to render a cached or freshly executed template. The particular line in question generated a "cache key" by running a template's variables through md5(serialize($vars)). This key is then included in a URI that is used to find a cached template.
