Towards understanding how developers spend their effort during maintenance activities

For many years, researchers and practitioners have strived to assess and improve the productivity of software development teams. One key step toward achieving this goal is the understanding of factors affecting the efficiency of developers performing development and maintenance activities. In this paper, we aim to understand how developers' spend their effort during maintenance activities and study the factors affecting developers' effort. By knowing how developers' spend their effort and which factors affect their effort, software organisations will be able to take the necessary steps to improve the efficiency of their developers, for example, by providing them with adequate program comprehension tools. For this preliminary study, we mine 2,408 developers' interaction histories and 3,395 patches from four open-source software projects (ECF, Mylyn, PDE, Eclipse Platform). We observe that usually, the complexity of the implementation required for a task does not reflect the effort spent by developers on the task. Most of the effort appears to be spent during the exploration of the program. In average, 62% of files explored during the implementation of a task are not significantly relevant to the final implementation of the task. Developers who explore a large number of files that are not significantly relevant to the solution to their task take a longer time to perform the task. We expect that the results of this study will pave the way for better program comprehension tools to guide developers during their explorations of software systems.