The Secret Life of Patches: A Firefox Case Study

The goal of the code review process is to assess the quality of source code modifications (submitted as patches) before they are committed to a project´s version control repository. This process is particularly important in open source projects to ensure the quality of contributions submitted by the community, however, the review process can promote or discourage these contributions. In this paper, we study the patch lifecycle of the Mozilla Fire fox project. The model of a patch lifecycle was extracted from both the qualitative evidence of the individual processes (interviews and discussions with developers), and the quantitative assessment of the Mozilla process and practice. We contrast the lifecycle of a patch in pre- and post-rapid release development. A quantitative comparison showed that while the patch lifecycle remains mostly unchanged after switching to rapid release, the patches submitted by casual contributors are disproportionately more likely to be abandoned compared to core contributors. This suggests that patches from casual developers should receive extra care to both ensure quality and encourage future community contributions.