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.

If you want a quick guide to getting your development environment setup, please use the contributing instructions on GitHub.

Certificate of Origin#

To keep a clear track of who did what, we use a sign-off procedure (same requirements for using the signed-off-by process as the Linux kernel has on patches or pull requests that are being sent. The sign-off is a simple line at the end of the explanation for the patch, which certifies that you wrote it or otherwise have the right to pass it on as an open-source patch. The rules are pretty simple: if you can certify the below:


“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.”

This is my commit message

Signed-off-by: Awesome Developer <>

Code without a proper signoff cannot be merged into the main 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 -m "This is my commit message"
git commit -s -m "This is my commit message"

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 "Awesome Developer"
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#

We request that your first commit follow a particular format, and we require that your PR title follow the format. The format is:

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

  • PERF: Performance enhancements

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

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

A Modin CI job on GitHub will enforce that your pull request title follows the format we suggest. Note that if you update the PR title, you have to push another commit (even if it’s empty) or amend your last commit for the job to pick up the new PR title. Re-running the job in Github Actions won’t work.

General Rules for committers#

  • Try to write a PR name as descriptive as possible.

  • Try to keep PRs as small as possible. One PR should be making one semantically atomic change.

  • Don’t merge your own PRs even if you are technically able to do it.

Development Dependencies#

We recommend doing development in a virtualenv or conda environment, 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:

conda env create --file environment-dev.yml
# or
pip install -r requirements-dev.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/ asv_bench/benchmarks scripts/

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

flake8 modin/ asv_bench/benchmarks scripts/

We test that this has been run on our Github Actions 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.

Performance measurement#

We use Asv tool for performance tracking of various Modin functionality. The results can be viewed here: Asv dashboard.

More information can be found in the Asv readme.

Building documentation#

To build the documentation, please follow the steps below from the project root:

pip install -r docs/requirements-doc.txt
sphinx-build -b html docs docs/build

To visualize the documentation locally, run the following from build folder:

python -m http.server <port>
# python -m http.server 1234

then open the browser at<port> (e.g.

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…