Beyond the Code: Mining Self-Admitted Technical Debt in Issue Tracker Systems

Self-admitted technical debt (SATD) is a particular case of Technical Debt (TD) where developers explicitly acknowledge their sub-optimal implementation decisions. Previous studies mine SATD by searching for specific TD-related terms in source code comments.By contrast, in this paper we argue that developers can admit technical debt by other means, e.g., by creating issues in tracking systems and labelling them as referring to TD. We refer to this type of SATD as issue-based SATD or just SATD-I. We study a sample of 286 SATD-I instances collected from five open source projects, including Microsoft Visual Studio and GitLab Community Edition. We show that only 29% of the studied SATD-I instances can be tracked to source code comments. We also show that SATD-I issues take more time to be closed, compared to other issues, although they are not more complex in terms of code churn. Besides, in 45% of the studied issues TD was introduced to ship earlier, and in almost 60%it refers to Design flaws. Finally, we report that most developers pay SATD-I to reduce its costs or interests (66%). Our findings suggest that there is space for designing novel tools to support technical debt management, particularly tools that encourage developers to create and label issues containing TD concerns.自我承认的技术债务（Self-admitted Technical Debt, SATD）是技术债务（Technical Debt, TD）的一类特定场景，指开发者明确承认自身存在非最优的实现决策。既往研究通过在源代码注释（source code comments）中检索特定技术债务相关术语的方式挖掘SATD。与之相对，本文主张开发者可通过其他途径承认技术债务，例如在议题追踪系统中创建议题并将其标记为涉及技术债务。我们将此类SATD称为基于议题的SATD（issue-based SATD），简称SATD-I。我们对从5个开源项目中采集的286个SATD-I实例样本进行了研究，这些项目涵盖微软Visual Studio与GitLab社区版。研究结果显示，仅29%的所分析SATD-I实例可追溯至源代码注释。此外我们还发现，相较于其他议题，SATD-I议题的关闭耗时更长，尽管二者在代码变更量（code churn）维度上并未表现出更高复杂度。在45%的所研究议题中，引入技术债务的目的是为了提前交付产品；而近60%的SATD-I议题涉及设计缺陷。最后，我们发现66%的开发者会通过清偿SATD-I来降低其成本与利息负担。我们的研究结果表明，当前仍存在设计新型工具以支撑技术债务管理的空间，尤其是那些能够鼓励开发者创建并标记包含技术债务相关事项的议题的工具。