We have quite a bit of infrastructure around this including Tinderbox Pushlog (TBPL) and more. This post deals with the infrastructure and problem we face while trying to scale the ’try’ repository. A few statistics: The try repository currently has 17943 heads. These heads are never removed. The try repository is about 3.6 GB in size. Due to Mercurial’s on-wire HTTP protocol, this number of heads causes HTTP cloning to fail There are roughly 81000 HTTP requests to try per day To fix problems (mentioned below), the try repository is deleted and re-cloned from mozilla-central every few months There are a number of problems associated with such a repository.