Software Reliability Growth Model Based on Stochastic Differential Equations for Open Source Software

All over the world people can gain the information at the same time by growing rate of Internet access around the world in recent years. In accordance with such a penetration of the Internet, it is increasing public awareness of the importance of online real-time and interactive functions. Therefore, software development environment has been changing into new development paradigms such as concurrent distributed development environment and the so-called open source project by using network computing technologies. Especially, such OSS (open source software) systems which serve as key components of critical infrastructures in our society are still ever-expanding now. In this paper, we propose a software reliability growth model based on stochastic differential equations in order to consider the active state of the open source project. Especially, we assume that the software failure intensity depends on the time, and the software fault-report phenomena on the bug tracking system keep an irregular state. Also, we analyze actual software fault count data to show numerical examples of software reliability assessment for the OSS. Moreover, we compare our model with the conventional model based on stochastic differential equations in terms of goodness-of-fit for actual data. We show that the proposed model can assist improvement of quality for OSS systems developed under the open source project.