On Wasted Contributions: Understanding the Dynamics of Contributor-Abandoned Pull Requests

TL;DR

This study analyzes the factors influencing abandoned pull requests in open-source projects, revealing that complexity, contributor experience, and review length significantly impact abandonment rates, with insights from data analysis and maintainer surveys.

Contribution

It provides a comprehensive mixed-methods analysis of abandoned PRs, combining quantitative data, qualitative examination, and maintainer perspectives to understand abandonment dynamics.

Findings

Complex PRs are more likely to be abandoned.

Novice contributors face higher abandonment risks.

Long review processes correlate with increased abandonment.

Abstract

Pull-based development has enabled numerous volunteers to contribute to open-source projects with fewer barriers. Nevertheless, a considerable amount of pull requests (PRs) with valid contributions are abandoned by their contributors, wasting the effort and time put in by both the contributors and maintainers. To better understand the underlying dynamics of contributor-abandoned PRs, we conduct a mixed-methods study using both quantitative and qualitative methods. We curate a dataset consisting of 265,325 PRs including 4,450 abandoned ones from ten popular and mature GitHub projects and measure 16 features characterizing PRs, contributors, review processes, and projects. Using statistical and machine learning techniques, we find that complex PRs, novice contributors, and lengthy reviews have a higher probability of abandonment and the rate of PR abandonment fluctuates alongside the projects' maturity or workload. To identify why contributors abandon their PRs, we also manually examine a random sample of 354 abandoned PRs. We observe that the most frequent abandonment reasons are related to the obstacles faced by contributors, followed by the hurdles imposed by maintainers during the review process. Finally, we survey the top core maintainers of the studied projects to understand their perspectives on dealing with PR abandonment and on our findings.