Case study: How much does it cost to maintain a copy of an open source software package (at Google)?

Open source software is used pervasively, with many citing cost benefits such as time saved in software engineering (SWE) hours. However, the actual costs to use open source software are non-zero and not often discussed or measured. We designed a study to evaluate the effort and cost (in SWE hours) associated with maintaining open source software forks within Google. Our study showed that the majority of updates take 4 hours or less, however the long tail could be days to months. Our results suggest that level of effort may be indicated by custom patches, external dependency volume, and project size, while package age and internal usage levels did not appear to have a consistent impact on update complexity.

• Software engineering