How the evolution of emerging collaborations relates to code changes: an empirical study

Developers contributing to open source projects spontaneously group into "emerging'' teams, reflected by messages exchanged over mailing lists, issue trackers and other communication means. Previous studies suggested that such teams somewhat mirror the software modularity. This paper empirically investigates how, when a project evolves, emerging teams re-organize themselves-e.g., by splitting or merging. We relate the evolution of teams to the files they change, to investigate whether teams split to work on cohesive groups of files. Results of this study-conducted on the evolution history of four open source projects, namely Apache httpd, Eclipse JDT, Netbeans, and Samba-provide indications of what happens in the project when teams reorganize. Specifically, we found that emerging team splits imply working on more cohesive groups of files and emerging team merges imply working on groups of files that are cohesive from structural perspective. Such indications serve to better understand the evolution of software projects. More important, the observation of how emerging teams change can serve to suggest software remodularization actions.