Researchers apply machine-learning techniques for code smell detection to counter the subjectivity of many code smells. Such approaches need a large, manually annotated dataset for training and benchmarking. Existing literature offers a few datasets; however, they are small in size and, more importantly, do not focus on the subjective code snippets. In this paper, we present DACOS, a manually annotated dataset containing 10, 267 annotations for 5, 192 code snippets. The dataset targets three kinds of code smells at different granularity–multifaceted abstraction, complex method, and long parameter list. The dataset is created in two phases. The first phase helps us identify the code snippets that are potentially subjective by determining the thresholds of metrics used to detect a smell. The second phase collects annotations for potentially subjective snippets. We also offer an extended dataset DACOSX that includes definitely benign and definitely smelly snippets by using the thresholds identified in the first phase. We have developed TAGMAN, a web application to help annotators view and mark the snippets one-by-one and record the provided annotations. We make the datasets and the web application accessible publicly. This dataset will help researchers working on smell detection techniques to build relevant and context-aware machine-learning models.

Code smells are inherently subjective in nature. Software developers may have different opinions and perspectives on smelly code. While many attempts have been made to use deep learning-based models for code smell detection, they fail to consider each developer’s subjective perspective while detecting smells. Ignoring this aspect defies the purpose of using deep learning-based smell detection methods because the models are not customized to the developer’s context. This paper proposes a method that considers human feedback to account for such subjectivity. Towards this, we created a plugin for IntelliJ IDEA and developed a container-based web-server to offer services of our baseline deep learning model. The setup allowed developers to see code smells within the IDE and provide feedback. Using this setup, we conducted a controlled experiment with 14 participants divided into experimental and control groups. In the first round of our experiment, we show code smells predicted using the baseline deep learning model and collect feedback from the participants. In the second round, we fine-tune the model based on the experimental group’s feedback and reevaluate its performance before and after adjustment. Our results show that using such calibration improves the performance of the smell detection model by 15.49% in F1 score on average across the participants of the experimental group. Our work carries implications for both researchers and practitioners. Practitioners can apply our approach to enhance the quality of their code in day-to-day development activities, aligning it with their own code smell definitions. Furthermore, software engineering researchers can leverage this study to adopt analogous approaches for addressing similar issues, including code review.