Examining the effects of developer familiarity on bug fixing

Background: In modern software systems' maintenance and evolution, how to fix software bugs efficiently and effectively becomes increasingly more essential. A deep understanding of developers'/assignees' familiarity with bugs could help project managers make a proper allotment of maintenance resources. However, to our knowledge, the effects of developer familiarity on bug fixing have not been studied. Aims: Inspired by the understanding of developers'/assignees' familiarity with bugs, we aim to investigate the effects of familiarity on efficiency and effectiveness of bug fixing. Method: Based on evolution history of buggy code lines, we propose three metrics to evaluate the developers'/assignees' familiarity with bugs. Additionally, we conduct an empirical study on 6 well-known Apache Software Foundation projects with more than 9000 confirmed bugs. Results: We observe that (a) familiarity is one of the common factors in cases of bug fixing: the developers are more likely to be assigned to fix the bugs introduced by themselves; (b) familiarity has complex effects on bug fixing: although the developers fix the bugs introduced by themselves more quickly (with high efficiency), they are more likely to introduce future bugs when fixing the current bugs (with worse effectiveness). Conclusion: We put forward the following suggestions: (a) managers should assign some outsiders to participate in bug fixing. (b) when developers deal with his own code, managers should assign more maintenance resource (e.g., more inspection) to developers. (C) 2020 Elsevier Inc. All rights reserved.