Evolution of Open Source Software Systems – A Large-Scale Investigation

In this paper, the evolution of a large sample of open source software projects will be analysed. The evolution of commercial systems has been an issue that has long been a center of research, thus a coherent theoretical framework of software evolution has been developed and empirically tested. Therefore these results can be used to compare the situation in open source projects to the evolution of commercial projects. This allows to assess whether the underlying software process indeed significantly differs. The data collection methodology relying on a large software repository and the respective source code control systems is described, and an overview on the collected data on several thousand projects is given. The evolutionary behaviour is explored using both a linear and a quadratic model, with the quadratic model significantly outperforming the linear one. The most interesting fact is that while in the mean the growth rate is decreasing over time according to the l...