Towards Understanding Interactive Debugging

Abstract

Debugging is a laborious activity in which developers spend lot of time navigating through code, looking for starting points, and stepping through statements. Yet, although debuggers exist for 40 years now, there have been few research studies to understand this important and laborious activity. Indeed, to perform such a study, researchers need detailed information about the different steps of the interactive debugging process. In this paper, to help research studies on debugging and, thus, help improving our understanding of how developers debug systems using debuggers, we present the Swarm Debug Infrastructure (SDI), with which practitioners and researchers can collect and share data about developers' interactive debugging activities. We assess the effectiveness of the SDI through an experiment that aims to understand how developers apply interactive debugging on five true faults found in JabRef, toggling breakpoints and stepping code. Our study involved five freelancers and two student developers performing 19 bug location sessions. We collect videos recording and data about 6 hours of effective debugging activities. The data includes 110 breakpoints and near 7,000 invocations. We process the collected videos and data to answer five research questions showing that (1) there is no correlation between the number of invocations (respectively the number of breakpoints toggled) during a debugging session and the time spent on the debugging task, ρ = -0.039 (respectively 0.093). We also observed that (2) developers follow different debugging patterns and (3) there is no relation between numbers of breakpoints and expertise. However, (4) there is a strong negative correlation between time of the first breakpoint (ρ = -0.637), and the time spent on the task, suggesting that when developers toggle breakpoints carefully, they complete tasks faster than developers who toggle breakpoints too quickly. We conclude that the SDI allows collecting and sharing debugging data that can provide interesting insights about interactive debugging activities. We discuss some implications for tool developers and future debuggers.