Usage, Costs, and Benefits of Continuous Integration in Open-Source Projects Michael Hilton Timothy Tunnell Kai Huang Oregon State University University of Illinois at University of Illinois at
[email protected] Urbana-Champaign Urbana-Champaign
[email protected] [email protected] Darko Marinov Danny Dig University of Illinois at Oregon State University Urbana-Champaign
[email protected] [email protected] ABSTRACT CI using several quality metrics. However, the study does Continuous integration (CI) systems automate the compi- not present any detailed information about the use of CI. lation, building, and testing of software. Despite CI rising In fact, despite some folkloric evidence about the use of CI, as a big success story in automated software engineering, it there is no systematic study about CI systems. has received almost no attention from the research commu- Not only do we lack basic knowledge about the extent nity. For example, how widely is CI used in practice, and to which open-source projects are adopting CI, but also what are some costs and benefits associated with CI? With- we have no answers to many other important questions re- out answering such questions, developers, tool builders, and lated to CI. What are the costs of CI? Does CI deliver researchers make decisions based on folklore instead of data. on the promised benefits, such as releasing more often, or In this paper, we use three complementary methods to helping make changes (e.g., to merge pull requests) faster? study in-depth the usage of CI in open-source projects. To Are developers maximizing the usage of CI? Despite the understand what CI systems developers use, we analyzed widespread popularity of CI, we have very little quantita- 34,544 open-source projects from GitHub.