TechRxiv
Employing code embeddings to detect code smells.pdf (544.83 kB)
Download file

Automatic detection of Long Method and God Class code smells through neural source code embeddings

Download (544.83 kB)
preprint
posted on 22.12.2021, 10:13 by Aleksandar Kovačević, Jelena SlivkaJelena Slivka, Dragan Vidaković, Katarina-Glorija Grujić, Nikola LuburićNikola Luburić, Simona Prokić, Goran Sladić

Code smells are structures in code that often have a negative impact on its quality. Manually detecting code smells is challenging and researchers proposed many automatic code smell detectors. Most of the studies propose detectors based on code metrics and heuristics. However, these studies have several limitations, including evaluating the detectors using small-scale case studies and an inconsistent experimental setting. Furthermore, heuristic-based detectors suffer from limitations that hinder their adoption in practice. Thus, researchers have recently started experimenting with machine learning (ML) based code smell detection.

This paper compares the performance of multiple ML-based code smell detection models against multiple traditionally employed metric-based heuristics for detection of God Class and Long Method code smells. We evaluate the effectiveness of different source code representations for machine learning: traditionally used code metrics and code embeddings (code2vec, code2seq, and CuBERT).

We perform our experiments on the large-scale, manually labeled MLCQ dataset. We consider the binary classification problem – we classify the code samples as smelly or non-smelly and use the F1-measure of the minority (smell) class as a measure of performance. In our experiments, the ML classifier trained using CuBERT source code embeddings achieved the best performance for both God Class (F-measure of 0.53) and Long Method detection (F-measure of 0.75). With the help of a domain expert, we perform the error analysis to discuss the advantages of the CuBERT approach.

This study is the first to evaluate the effectiveness of pre-trained neural source code embeddings for code smell detection to the best of our knowledge. A secondary contribution of our study is the systematic evaluation of the effectiveness of multiple heuristic-based approaches on the same large-scale, manually labeled MLCQ dataset.

Funding

This research was supported by the Science Fund of the Republic of Serbia, Grant No 6521051, AI-Clean CaDET.

History

Email Address of Submitting Author

slivkaje@uns.ac.rs

ORCID of Submitting Author

https://orcid.org/0000-0003-0351-1183

Submitting Author's Institution

Faculty of Technical Sciences, University of Novi Sad

Submitting Author's Country

Serbia