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Why and how developers fork what from whom in GitHub

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Abstract

Forking is the creation of a new software repository by copying another repository. Though forking is controversial in traditional open source software (OSS) community, it is encouraged and is a built-in feature in GitHub. Developers freely fork repositories, use codes as their own and make changes. A deep understanding of repository forking can provide important insights for OSS community and GitHub. In this paper, we explore why and how developers fork what from whom in GitHub. We collect a dataset containing 236,344 developers and 1,841,324 forks. We make surveys, and analyze programming languages and owners of forked repositories. Our main observations are: (1) Developers fork repositories to submit pull requests, fix bugs, add new features and keep copies etc. Developers find repositories to fork from various sources: search engines, external sites (e.g., Twitter, Reddit), social relationships, etc. More than 42 % of developers that we have surveyed agree that an automated recommendation tool is useful to help them pick repositories to fork, while more than 44.4 % of developers do not value a recommendation tool. Developers care about repository owners when they fork repositories. (2) A repository written in a developer’s preferred programming language is more likely to be forked. (3) Developers mostly fork repositories from creators. In comparison with unattractive repository owners, attractive repository owners have higher percentage of organizations, more followers and earlier registration in GitHub. Our results show that forking is mainly used for making contributions of original repositories, and it is beneficial for OSS community. Moreover, our results show the value of recommendation and provide important insights for GitHub to recommend repositories.

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Notes

  1. http://github.com

  2. https://github.com/rowanj/gitx

  3. https://github.com/pieter/gitx

  4. http://developer.github.com/v3/

  5. https://github.com/blog/40-we-launched

  6. https://rubygems.org/

  7. https://github.com/explore

  8. http://github.com/equus12

  9. https://rubygems.org/

  10. https://github.com/lightbot/ForkResearch

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Acknowledgments

This work is supported by National Natural Science Foundation of China under Grant No.61300006, the State Key Laboratory of Software Development Environment under Grant No.SKLSDE-2015ZX-24, and Beijing Natural Science Foundation under Grant No.4163074.

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Authors and Affiliations

  1. State Key Laboratory of Software Development Environment, Beihang University, Beijing, China

    Jing Jiang, Jiahuan He & Li Zhang

  2. School of Information Systems, Singapore Management University, Singapore, Singapore

    David Lo & Pavneet Singh Kochhar

  3. College of Computer Science and Technology, Zhejiang University, Hangzhou, China

    Xin Xia

Authors
  1. Jing Jiang
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  2. David Lo
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  3. Jiahuan He
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  4. Xin Xia
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  5. Pavneet Singh Kochhar
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  6. Li Zhang
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Corresponding authors

Correspondence to Jing Jiang or Li Zhang.

Additional information

Communicated by: Massimiliano Di Penta

Li Zhang is the first corresponding author

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Jiang, J., Lo, D., He, J. et al. Why and how developers fork what from whom in GitHub. Empir Software Eng 22, 547–578 (2017). https://doi.org/10.1007/s10664-016-9436-6

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  • DOI: https://doi.org/10.1007/s10664-016-9436-6

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