Improving bug triage with bug tossing graphs

A bug report is typically assigned to a single developer who is then responsible for fixing the bug. In Mozilla and Eclipse, between 37%-44 % of bug reports are “tossed ” (reassigned) to other devel-opers, for example because the bug has been assigned by accident or another developer with additional expertise is needed. In any case, tossing increases the time-to-correction for a bug. In this paper, we introduce a graph model based on Markov chains, which captures bug tossing history. This model has sev-eral desirable qualities. First, it reveals developer networks which can be used to discover team structures and to find suitable experts for a new task. Second, it helps to better assign developers to bug reports. In our experiments with 445,000 bug reports, our model reduced tossing events, by up to 72%. In addition, the model in-creased the prediction accuracy by up to 23 percentage points com-pared to traditional bug triaging approaches. Categories and Subject Descriptors D2.7 [Software Engineering]: Distribution, Maintenance, and En