With a large and rapidly changing codebase, Google software engineers are
constantly paying interest on various forms of technical debt. Google engineers
also make efforts to pay down that debt, whether through special Fixit days, or via
dedicated teams, variously known as janitors, cultivators, or demolition experts.
We describe several related efforts to measure and pay down technical debt found in
Google's BUILD files and associated dead code. We address debt found in dependency
specifications, unbuildable targets, and unnecessary command line flags. These
efforts often expose other forms of technical debt that must first be managed.