Characterizing and predicting blocking bugs in open source projects

Software engineering researchers have studied specific types of issues such reopened bugs, performance bugs, dormant bugs, etc. However, one special type of severe bugs is blocking bugs. Blocking bugs are software bugs that prevent other bugs from being fixed. These bugs may increase maintenance costs, reduce overall quality and delay the release of the software systems. In this paper, we study blocking bugs in eight open source projects and propose a model to predict them early on. We extract 14 different factors (from the bug repositories) that are made available within 24 hours after the initial submission of the bug reports. Then, we build decision trees to predict whether a bug will be a blocking bugs or not. Our results show that our prediction models achieve F-measures of 21%-54%, which is a two-fold improvement over the baseline predictors. We also analyze the fixes of these blocking bugs to understand their negative impact. We find that fixing blocking bugs requires more lines of code to be touched compared to non-blocking bugs. In addition, our file-level analysis shows that files affected by blocking bugs are more negatively impacted in terms of cohesion, coupling complexity and size than files affected by non-blocking bugs.