An Empirical Study of Link Sharing in Review Comments

In the pull-based development, developers sometimes exchange review comments and share links, namely Uniform Resource Locators (URLs). Links are used to refer to related information from different websites, which may be beneficial to pull request evaluation. Nevertheless, little effort has been done on analyzing how links are shared and whether sharing links has any impacts on code review in GitHub. In this paper, we conduct a study of link sharing in review comments. We collect 114,810 pull requests and 251,487 review comments from 10 popular projects in GitHub. We find that 5.25% of pull requests have links in review comments on average. We divide links into two types: internal links which point to context in the same project, and external links which point to context outside of the project. We observe that 51.49% of links are internal, while 48.51% of links are external. The majority of internal links point to pull requests or blobs inside projects. We further study impacts of links. Results show that pull requests with links in review comments have more comments, more commenters and longer evaluation time than pull requests without links. These findings show that developers indeed share links and refer to related information in review comments. These results inspire future studies which enable more effective information sharing in the open source community, and improve information accessibility and navigability for software developers.