A First Look at Duplicate and Near-duplicate Self-admitted Technical Debt Comments

Self-admitted technical debt (SATD) refers to technical debt that is intentionally introduced by developers and explicitly documented in code comments or other software artifacts (e.g., issue reports) to annotate sub-optimal decisions made by developers in the software development process. In this work, we take the first look at the existence and characteristics of duplicate and near-duplicate SATD comments in five popular Apache OSS projects, i.e., JSPWiki, Helix, Jackrabbit, Archiva, and SystemML. We design a method to automatically identify groups of duplicate and near-duplicate SATD comments and track their evolution in the software system by mining the commit history of a software project. Leveraging the proposed method, we identified 3,520 duplicate and near-duplicate SATD comments from the target projects, which belong to 1,141 groups. We manually analyze the content and context of a sample of 1,505 SATD comments (by sampling 100 groups for each project) and identify if they annotate the same root cause. We also investigate whether duplicate SATD comments exist in code clones, whether they co-exist in the same file, and whether they are introduced and removed simultaneously. Our preliminary study reveals several surprising findings that would shed light on future studies aiming to improve the management of duplicate SATD comments. For instance, only 48.5% duplicate SATD comment groups with the same root cause exist in regular code clones, and only 33.9% of the duplicate SATD comment pairs are introduced in the same commit.