GPP: A Graph-Powered Prioritizer for Code Review Requests

Peer code review has become a must-have in modern software development. However, many code review requests (CRRs) could be a backlog for large-scale and active projects, blocking continuous integration and continuous delivery (CI/CD). Prioritizing CRRs to make the relevant ones to be reviewed first is a critical method for addressing this issue. Early studies have shown that many factors affect the review priority of a CRR, including its properties and relationships with other CRRs. However, the relationships, e.g., modifying the same files and sharing the same authors, are rarely considered when developing CRR prioritizers. In this paper, we propose a Graph-Powered Prioritizer (namely GPP) to make full use of the properties and relationships of CRRs. GPP uses the multi-graph structure to develop an initial representation of a collection of CRRs and uses the graph neural network algorithm to learn the prioritization-adapted representation, and eventually, outputs an ordered list of CRRs based on it. With experimental evaluation, we define relevant CRRs in the context of CI/CD as those that are likely to achieve three objectives, i.e., being merged while undergoing a few iterations in a short duration. We compare GPP against two rule-based and six learning-based prioritizers on 15 open-source software projects with more than 420K CRRs. The experimental results indicate that GPP outperforms the baselines on three basic ranking-aware evaluation metrics, including NDCG (82.94%), MRR (36.52%), and MAP (63.80%); while providing benefits in recommending the most relevant CRRs and balancing multiple objectives. Data&materials: https://figshare.com/s/133f23da558b7b254041