Getting Started

If you’re interested in getting involved in the development of Modin, but aren’t sure where start, take a look at the issues tagged Good first issue or Documentation. These are issues that would be good for getting familiar with the codebase and better understanding some of the more complex components of the architecture. There is documentation here about the architecture that you will want to review in order to get started.

Also, feel free to join the discussions on the developer mailing list.


“By making a contribution to this project, I certify that:

1.) The contribution was created in whole or in part by me and I have the right to submit it under the open source license indicated in the file; or 2.) The contribution is based upon previous work that, to the best of my knowledge, is covered under an appropriate open source license and I have the right under that license to submit that work with modifications, whether created in whole or in part by me, under the same open source license (unless I am permitted to submit under a different license), as indicated in the file; or 3.) The contribution was provided directly to me by some other person who certified (a), (b) or (c) and I have not modified it. 4.) I understand and agree that this project and the contribution are public and that a record of the contribution (including all personal information I submit with it, including my sign-off) is maintained indefinitely and may be redistributed consistent with this project or the open source license(s) involved.”

How to sign-off commits

Modin requires a sign-off message in the following format appear on each commit in the pull request:

This is my commit message

Signed-off-by: Random J Developer <>

We have the same requirements for using the signed-off-by process as the Linux kernel has.

In short, you need to include a signed-off-by tag in every patch:

Signed-off-by is a developer’s certification that he or she has the right to submit the patch for inclusion into the project. It is an agreement to the Developer’s Certificate of Origin (above). Code without a proper signoff cannot be merged into the master branch. Note: You must use your real name (sorry, no pseudonyms or anonymous contributions.)

The text can either be manually added to your commit body, or you can add either -s or --signoff to your usual git commit commands:

git commit --signoff
git commit -s

This will use your default git configuration which is found in .git/config. To change this, you can use the following commands:

git config --global "FIRST_NAME LAST_NAME"
git config --global ""

If you have authored a commit that is missing the signed-off-by line, you can amend your commits and push them to GitHub.

git commit --amend --signoff

If you’ve pushed your changes to GitHub already you’ll need to force push your branch after this with git push -f.

Commit Message formatting

To ensure that all commit messages in the master branch follow a specific format, we enforce that all commit messages must follow the following format:

FEAT-#9999: Add `DataFrame.rolling` functionality, to enable rolling window operations

The FEAT component represents the type of commit. This component of the commit message can be one of the following:

  • FEAT: A new feature that is added
  • DOCS: Documentation improvements or updates
  • FIX: A bugfix contribution
  • REFACTOR: Moving or removing code without change in functionality
  • TEST: Test updates or improvements

The #9999 component of the commit message should be the issue number in the Modin GitHub issue tracker: This is important because it links commits to their issues.

The commit message should follow a colon (:) and be descriptive and succinct.

Development Dependencies

We recommend doing development in a virtualenv, though this decision is ultimately yours. You will want to run the following in order to install all of the required dependencies for running the tests and formatting the code:

pip install -r requirements.txt

Code Formatting and Lint

We use black for code formatting. Before you submit a pull request, please make sure that you run the following from the project root:

black modin/

We also use flake8 to check linting errors. Running the following from the project root will ensure that it passes the lint checks on Travis:

flake8 .

We test that this has been run on our Travis CI test suite. If you do this and find that the tests are still failing, try updating your version of black and flake8.

Adding a test

If you find yourself fixing a bug or adding a new feature, don’t forget to add a test to the test suite to verify its correctness! More on testing and the layout of the tests can be found in our testing documentation. We ask that you follow the existing structure of the tests for ease of maintenance.

Running the tests

To run the entire test suite, run the following from the project root:

pytest modin/pandas/test

The test suite is very large, and may take a long time if you run every test. If you’ve only modified a small amount of code, it may be sufficient to run a single test or some subset of the test suite. In order to run a specific test run:

pytest modin/pandas/test::test_new_functionality

The entire test suite is automatically run for each pull request.

Contributing a new execution framework or in-memory format

If you are interested in contributing support for a new execution framework or in-memory format, please make sure you understand the architecture of Modin.

The best place to start the discussion for adding a new execution framework or in-memory format is the developer mailing list.

More docs on this coming soon…