Rate-Based Queueing Simulation Model of Open Source Software Debugging Activities

Open source software (OSS) approach has become increasingly prevalent for software development. As the widespread utilization of OSS, the reliability of OSS products becomes an important issue. By simulating the testing and debugging processes of software life cycle, the rate-based queueing simulation model has shown its feasibility for closed source software (CSS) reliability assessment. However, the debugging activities of OSS projects are different in many ways from those of CSS projects and thus the simulation approach needs to be calibrated for OSS projects. In this paper, we first characterize the debugging activities of OSS projects. Based on this, we propose a new rate-based queueing simulation framework for OSS reliability assessment including the model and the procedures. Then a decision model is developed to determine the optimal version-updating time with respect to two objectives: minimizing the time for version update, and maximizing OSS reliability. To illustrate the proposed framework, three real datasets from Apache and GNOME projects are used. The empirical results indicate that our framework is able to effectively approximate the real scenarios. Moreover, the influences of the core contributor staffing levels are analyzed and the optimal version-updating times are obtained.