How Are Issue Units Linked? Empirical Study on the Linking Behavior in GitHub

摘要

Issue reports and Pull Requests (PRs) are two important kinds of artifacts of software projects in GitHub. It is common for developers to leave explicit links in issues/PRs that refer to the other issues/PRs during discussions. Existing studies have demonstrated the value of such links in identifying complex bugs and duplicate issue reports. However, there are no broad examinations of why developers leave links within issues/PRs and the potential impact of such links on software development. Without such knowledge, practitioners and researchers may miss various opportunities to develop practical techniques for better solving bug-fixing or feature implementation related tasks. To fill this gap, we conducted the first empirical study to explore the characteristics of a large number of links within 642,281 issues/PRs of 16,584 popular (>50 stars) Python projects in GitHub. Specifically, we first constructed an Issue Unit Network (IUN, we refer to issue reports or PRs as issue units) by making use of the links between issue units. Then, we manually checked a sample of 1,384 links in the IUN and concluded six major kinds of linking relationships between issue units. For each kind of linking relationships, we presented some common patterns that developers usually adopted while linking issue units. By further analyzing as many as 423,503 links that match these common patterns, we found several interesting findings which indicate potential research directions in the future, including detecting cross-project duplicate issue reports, using IUN to help better identify influential projects and core issue reports.