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This is is the GHTorrent FAQ (work in progress). Please ask more questions using the form below or by editing this file directly on GitHub.

General

What is GHTorrent?

GHTorrent collects all information from the GitHub API and populates with it two databases: one with raw data and one with linked entities. Using this data, users can get insights just for their repositories or for the full state of OSS development on GitHub.

GHTorrent has been extensively used by researchers, companies and OSS projects as a source of software process and product analytics.

Can I use GHTorrent for my research?

Absolutely! Lots of researchers have done so. You can download the database dumps or use the online access services to get access to the data.

When using GHTorrent data for research or large scale repository analysis, please consider the perils reported in this paper.

Which license is GHTorrent distributed under?

The GHTorrent dataset is distributed under a dual licensing scheme (Creative Commons +).

For non-commercial uses (including, but not limited to, educational, research or personal uses), the dataset is distributed under the CC-BY-SA license. Creative Commons License

For commercial uses, please contact the maintainer for more information. Usually, a sizable donation to the project will be enough to grant you full access.

Who is behind GHTorrent?

GHTorrent was initially created and is currently maintained by Georgios Gousios, with initial design support and ideas from Diomidis Spinellis. Several users have contributed code, ideas and support over time. Here is a (hopefuly not partial) list of them:

Sebastian Bates, Derek Brown, Arie van Deursen, Daniel German, Jeff McAffer, Bogdan Vasilescu

Financial support has been provided by the following organizations:

  • TU Delft: purchace and running costs for initial servers (2012 -- late 2015)
  • Microsoft: donation of Azure tokens for running the project infrastructure (late 2015 -- late 2016)

How is GHTorrent different from Github Archive?

Github Archive collects and stores the GitHub event stream. In addition to that, GHTorrent applies dependency based retrieval on all entities (e.g. commits, pull requests etc) that are linked from the events and stores the results in two databases: a raw data one (MongoDB) that stores the unprocessed responses from GitHub API and a relational one (MySQL) that stores links between the entities (e.g. commits are linked to projects). Using GHTorrent, developers can obtain an up-to-date, relational view of their project’s GitHub metadata, which can be used for answering questions regarding their project’s processes.

How can I...?

...contribute to GHTorrent?

Please read the contribution guide.

... cite the GHTorrent data set?

Georgios Gousios: The GHTorrent dataset and tool suite. MSR 2013: 233-236

@inproceedings{Gousi13,
  author = {Gousios, Georgios},
  title = {The GHTorrent dataset and tool suite},
  booktitle = {Proceedings of the 10th Working Conference on Mining Software
    Repositories},
  series = {MSR '13},
  year = {2013},
  isbn = {978-1-4673-2936-1},
  location = {San Francisco, CA, USA},
  pages = {233--236},
  numpages = {4},
  url = {http://dl.acm.org/citation.cfm?id=2487085.2487132},
  acmid = {2487132},
  publisher = {IEEE Press},
  address = {Piscataway, NJ, USA},
}

...download the data?

You don't need to. GHTorrent offers a multitude of online services that enable access to almost realtime versions of the datastores. If you really want to, you can get all the data from the downloads page.

...use the data for my private project?

See the licensing information above.

Data processing

What quality guarantees does GHTorrent offer?

The GHTorrent data come as is with no quality guarantees. However, we are actively seeking to fix systematic (i.e. errors that are repeated across the whole dataset) data collection errors. Please open an issue if you find one. As GHTorrent is essentially a data sync operation over unreliable networks, spurious inconsistencies such as (minor) holes in data collection are unavoidable.

I 've seen weird commit timestamps

Git records the commit timestamp on the developer's workstation. If the clock is missconfigured, timestamps will be weird. We have seen timestamps such as 0000-01-01 00:00 or 2034-12-31 23:59. GitHub and GHTorrent do not process the timestamps in any way.

My data is out of date

Github only creates events when an entity is created and not when it is updated or deleted. It is therefore not possible to be completely up-to-date with changes in users (e.g. updated location) and repositories (e.g. renames). GHTorrent tries its best to stay up to date by refreshing all users and all repos every X months. As the DB contains 12M+ users and 30M+ repos, this process may take a while and it can also fail due to spurious reasons.

Copyright and Privacy

Who owns the data that GHTorrent shares?

The copyright situation is very complicated; in essense, GitHub owns copyright to the data formats for the API responses, users own copyright of the content they create and the GHTorrent creator has copyright on the GHTorrent database schemata.

What types of privacy guarantees does GHTorrent offer?

GHTorrent collects publicly available data from the GitHub API.

How does GHTorrent handle my personal information?

By personal information, we mean data that identify a real person uniquely. In the context of GHTorrent, these are emails and real names.

As of Mar 2016, GHTorrent does not distribute any personal information by default. Researchers whose research requires access to personal data can use this form to obtain it.

Can I get more information?

Yes. Please read the following Slidedeck. If you are still in doubt, please contact us.

How can I opt out?

We understand that being part of such a big dataset can have concequences for your online privacy. For this reason (and also to comply with legal data processing requirements), you can opt out data collection. If you want to opt out, please send us an email.

Opting out means that we will replace your email in the database with no-spam@ghtorrent.org and remove your real name.

Contacting users for surveys

(by @slang800)

Contacting GitHub users is sometimes necessary for research projects, but certain people regard this as spam and do not appreciate it. Even people who would ordinarily be willing to help in surveys can end up becoming hostile to requests due to the frequency with which they receive them. Due to the number of researchers who study the free software community, we have to be mindful of how many emails we are sending. Here are some tips to avoid annoying people:

  • Do not contact users who have signed up for the do-not-survey-list. These users have explicitly stated that they don't want to be involved in surveys.

  • Try to limit your data collection to a sample of users. While it may be tempting to contact all 12 million developers, it is also likely to leave a bad impression of researchers in general, and can make future studies difficult.

  • Don't contact people repeatedly if they fail to reply to your first email. If they weren't interested the first time, follow-ups are much more likely to bother them.

  • Don't contact people who have chosen to hide their email address from their profile page. People frequently assume that hiding their email from their profile will prevent them from being contacted. Sometimes, they don't even realize that every commit they make is signed with their email, so we shouldn't assume that users are consenting to being contacted, without checking the display settings on their profile.

  • Be especially careful when contacting highly-active developers. Not only to these people receive a massive amount of regular email from their participation in the free software community, but they are the sent a higher-than-average number of requests for surveys too.

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