Global software development in the freeBSD project

FreeBSD is a sophisticated operating system developed and maintained as open-source software by a team of more than 350 individuals located throughout the world. This study uses developer location data, the configuration management repository, and records from the issue database to examine the extent of global development and its effect on productivity, quality, and developer cooperation. The key findings are that global development allows round-the-clock work, but there are some marked differences between the type of work performed at different regions. The effects of multiple dispersed developers on the quality of code and productivity are negligible. Mentoring appears to be sometimes associated with developers living closer together, but ad-hoc cooperation seems to work fine across continents.