Exploring the Notion of Risk in Code Reviewer Recommendation
Bibliographic record
Abstract
Reviewing code changes allows stakeholders to improve the premise, content, and structure of changes prior to or after integration. However, assigning reviewing tasks to team members is challenging, particularly in large projects. Code reviewer recommendation has been proposed to assist with this challenge. Traditionally, the performance of reviewer recommenders has been derived based on historical data, where better solutions are those that recommend exactly which reviewers actually performed tasks in the past. More recent work expands the goals of recommenders to include mitigating turnover-based knowledge loss and avoiding overburdening the core development team. In this paper, we set out to explore how reviewer recommendation can incorporate the risk of defect proneness. To this end, we propose the Changeset Safety Ratio (CSR) – an evaluation measurement designed to capture the risk of defect proneness. Through an empirical study of three open source projects, we observe that: (1) existing approaches tend to improve one or two quantities of interest, such as core developers workload while degrading others (especially the CSR); (2) Risk Aware Recommender (RAR) – our proposed enhancement to multi-objective reviewer recommendation – achieves a 12.48% increase in expertise of review assignees and a 80% increase in CSR with respect to historical assignees, all while reducing the files at risk of knowledge loss by 19.39% and imposing a negligible 0.93% increase in workload for the core team; and (3) our dynamic method outperforms static and normalization-based tuning methods in adapting RAR to suit risk-averse and balanced risk usage scenarios to a significant degree (Conover's test, α < 0.05; small to large Kendall's W).
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.086 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.006 |
| Open science | 0.002 | 0.002 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".