ALFAA: Active Learning Fingerprint based Anti-Aliasing for correcting developer identity errors in version control systems

An accurate determination of developer identities is important for software engineering research and practice. Without it, even simple questions such as “how many developers does a project have?” cannot be answered. The commonly used version control data from Git is full of identity errors and the existing approaches to correct these errors are difficult to validate on large scale and cannot be easily improved. We, therefore, aim to develop a scalable, highly accurate, easy to use and easy to improve approach to correct software developer identity errors. We first amalgamate developer identities from version control systems in open source software repositories and investigate the nature and prevalence of these errors, design corrective algorithms, and estimate the impact of the errors on networks inferred from this data. We investigate these questions using a collection of over 1B Git commits with over 23M recorded author identities. By inspecting the author strings that occur most frequently, we group identity errors into categories. We then augment the author strings with three behavioral fingerprints: time-zone frequencies, the set of files modified, and a vector embedding of the commit messages. We create a manually validated set of identities for a subset of OpenStack developers using an active learning approach and use it to fit supervised learning models to predict the identities for the remaining author strings in OpenStack. We then compare these predictions with a competing commercially available effort and a leading research method. Finally, we compare network measures for file-induced author networks based on corrected and raw data. We find commits done from different environments, misspellings, organizational ids, default values, and anonymous IDs to be the major sources of errors. We also find supervised learning methods to reduce errors by several times in comparison to existing research and commercial methods and the active learning approach to be an effective way to create validated datasets. Results also indicate that correction of developer identity has a large impact on the inference of the social network. We believe that our proposed Active Learning Fingerprint Based Anti-Aliasing (ALFAA) approach will expedite research progress in the software engineering domain for applications that involve developer identities.