We Don’t Need Another Hero? The Impact of łHeroesž on Sofware Development Amritanshu Agrawal, Akond Rahman, Rahul Krishna, Alexander Sobran* and Tim Menzies Computer Science, NCSU, USA; IBM Corp*, Research Triangle, North Carolina [aagrawa8,aarahman,rkrish11]@ncsu.edu,asobran@us.ibm.com,tim@menzies.us ABSTRACT A software project has “Hero Developersž when 80% of contribu- tions are delivered by 20% of the developers. Are such heroes a good idea? Are too many heroes bad for software quality? Is it better to have more/less heroes for diferent kinds of projects? To answer these questions, we studied 661 open source projects from Public open source software (OSS) Github and 171 projects from an Enterprise Github. We fnd that hero projects are very common. In fact, as projects grow in size, nearly all projects become hero projects. These fnd- ings motivated us to look more closely at the efects of heroes on software development. Analysis shows that the frequency to close issues and bugs are not signifcantly afected by the presence of heroes or project type (Public or Enterprise). Similarly, the time needed to resolve an issue/bug/enhancement is not afected by heroes or project type. This is a surprising result since, before look- ing at the data, we expected that increasing heroes on a project will slow down how fast that project reacts to change. However, we do fnd a statistically signifcant association between heroes, project types, and enhancement resolution rates. Heroes do not afect enhancement resolution rates in Public projects. However, in Enterprise projects, heroes increase the rate at which projects complete enhancements. In summary, our empirical results call for a revision of a long- held truism in software engineering. Software heroes are far more common and valuable than suggested by the literature, particularly for medium to large Enterprise developments. Organizations should refect on better ways to fnd and retain more of these heroes. CCS CONCEPTS · Software and its engineering → Agile software develop- ment; KEYWORDS Issue, Bug, Commit, Hero, Core, Github, Productivity ACM Reference Format: Amritanshu Agrawal, Akond Rahman, Rahul Krishna, Alexander Sobran* and Tim Menzies. 2018. We Don’t Need Another Hero?: The Impact of “Heroesž on Software Development . In ICSE-SEIP ’18: 40th International Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for proft or commercial advantage and that copies bear this notice and the full citation on the frst page. Copyrights for components of this work owned by others than ACM must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specifc permission and/or a fee. Request permissions from permissions@acm.org. ICSE-SEIP ’18, May 27-June 3, 2018, Gothenburg, Sweden © 2018 Association for Computing Machinery. ACM ISBN 978-1-4503-5659-6/18/05. . . $15.00 https://doi.org/10.1145/3183519.3183549 Conference on Software Engineering: Software Engineering in Practice Track, May 27-June 3, 2018, Gothenburg, Sweden. ACM, New York, NY, USA, 9 pages. https://doi.org/10.1145/3183519.3183549 1 INTRODUCTION Many projects are initiated by a project leader who stays in that project for the longest duration [40]. These leaders are the ones who moderate the projects, contributes the most, and stays the most active throughout the software development life cycle. Such developers are sometimes called Hero/ Core/ lone contributors [24]. In the literature [17, 35, 36, 39], it is usual to defne a hero project as one where 80% of the contributions are made by 20% of the developers. In the literature, it is usual to deprecate heroes [4, 7, 19, 28, 38] since they can become a bottleneck that slows down project development. That said, looking through the literature, we cannot see any large scale studies on the efect of heroes in Enterprise projects. Accordingly, to better understand the positive or negative impact of heroes in software development, we mined 661 Public open source software (OSS) projects and 171 Enterprise Github projects (we say that enterprise software are in-house proprietary projects that used public Github Enterprise repositories to manage their development). After applying statistical tests to this data, we found some surprises: • Hero projects are exceedingly common in both Public and En- terprise projects, and the ratio of hero programmers in a project does not afect the development process, at least for the metrics we looked, with two exceptions; • Exception #1: in larger projects, heroes are far more common, that is, large projects need their heroes; • Exception #2: heroes have a positive impact on Enterprise projects, specifcally, the more heroes, the faster the enhancement resolution rates to those kinds of projects. This was surprising since, before mining the data, our expectation was that heroes have a large negative efect on software develop- ment, particularly for Public projects where the work is meant to be spread around a large community. The rest of this paper explains how we made and justifed these fndings. This investigation is structured around the following re- search questions: • RQ1: How common are heroes? From this analysis, we found: Result 1 Over 77% projects exhibit the pattern that 20% of the total contrib- utors complete 80% of the contributions. This holds true for both Public and Enterprise projects . arXiv:1710.09055v2 [cs.SE] 20 Feb 2018