Attributes that may raise the occurrence of merge conflicts

José William Menezes,Catarina Costa,Bruno Trindade,João Felipe Pimentel,Leonardo Murta,Alexandre Plastino

doi:10.5753/jserd.2021.1911

Abstract

Collaborative software development typically involves the use of branches. The changes made in different branches are usually merged, and direct and indirect conflicts may arise. Some studies are concerned with investigating ways to deal with merge conflicts and measuring the effort that this activity may require. However, the investigation of factors that may reduce the occurrence of conflicts needs more and deeper attention. This paper aims at identifying and analyzing attributes of past merges with and without conflicts to understand what may induce direct conflicts. We analyzed 182,273 merge scenarios from 80 projects written in eight different programming languages to find characteristics that increase the chances of a merge to have a conflict. We found that attributes such as the number of changed files, the number of commits, the number of changed lines, and the number of committers demonstrated to have the strongest influence in the occurrence of merge conflicts. Moreover, attributes in the branch that is being integrated seem to be more influential than the same attributes in the receiving branch. Additionally, we discovered positive correlations between the occurrence of conflicts and both the duration of the branch and the intersection of developers in both branches. Finally, we observed that PHP, JavaScript, and Java are more prone to conflicts.

Highlights

We found that attributes such as the number of changed files, the number of commits, the number of changed lines, and the number of committers demonstrated to have the strongest influence in the occurrence of merge conflicts
We divided the dataset of 182,273 merges into two subsets: one with 164,454 merges without conflicts and the other with 17,819 merges with conflicts
We found four attributes with a large effect size and five with a small effect size

Summary

Introduction

Software development normally involves collaboration among members of the project team. This collaborative development is supported by a Version Control System (VCS). Often, when there is a need to develop new features or fix bugs, developers choose to create a branch, which is a separate development line. This separate development line helps teams to focus on their tasks, without prematurely worrying about how it affects other parts of the software (Bird et al, 2011). According to Bird et al (2011), the effort involved in the merge process is dependent on how much work went on in the branches

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