  Social organization and division of labor crucially influence the performance
of collaborative software engineering efforts. In this paper, we provide a
quantitative analysis of the relation between social organization and
performance in Gentoo, an Open Source community developing a Linux
distribution. We study the structure and dynamics of collaborations as recorded
in the project's bug tracking system over a period of ten years. We identify a
period of increasing centralization after which most interactions in the
community were mediated by a single central contributor. In this period of
maximum centralization, the central contributor unexpectedly left the project,
thus posing a significant challenge for the community. We quantify how the
rise, the activity as well as the subsequent sudden dropout of this central
contributor affected both the social organization and the bug handling
performance of the Gentoo community. We analyze social organization from the
perspective of network theory and augment our quantitative findings by
interviews with prominent members of the Gentoo community which shared their
personal insights.
