Releasing pip 20.3, featuring new dependency resolver

On behalf of the Python Packaging Authority and the pip team, I am pleased to announce that we have just released pip 20.3, a new version of pip. You can install it by running python -m pip install --upgrade pip.

This is an important and disruptive release -- we explained why in a blog post last year. We've even made a video about it.

Highlights

• DISRUPTION: Switch to the new dependency resolver by default. Watch out for changes in handling editable installs, constraints files, and more: https://pip.pypa.io/en/latest/user_guide/#changes-to-the-pip-dependency-resolver-in-20-3-2020

• DEPRECATION: Deprecate support for Python 3.5 (to be removed in pip 21.0).

• DEPRECATION: pip freeze will stop filtering the pip, setuptools, distribute and wheel packages from pip freeze output in a future version. To keep the previous behavior, users should use the new --exclude option.

• Substantial improvements in new resolver for performance, output and error messages, avoiding infinite loops, and support for constraints files.

• Support for PEP 600: Future manylinux Platform Tags for Portable Linux Built Distributions.

• Documentation improvements: Resolver migration guide, quickstart guide, and new documentation theme.

• Add support for MacOS Big Sur compatibility tags.

The new resolver is now on by default for Python 3 users. It is significantly stricter and more consistent when it receives incompatible instructions, and reduces support for certain kinds of constraints files, so some workarounds and workflows may break. Please see our guide on how to test and migrate, and how to report issues. You can use the deprecated (old) resolver, using the flag --use-deprecated=legacy-resolver, until we remove it in the pip 21.0 release in January 2021.

You can find more details (including deprecations and removals) in the changelog.

Coming soon: end of Python 2.7 support

We aim to release pip 21.0 in January 2021, per our release cadence. At that time, pip will stop supporting Python 2.7 and will therefore stop supporting Python 2 entirely.

 

When users use pip 20.3 in a Python 2 environment, the old dependency resolver is still the default.

For more info or to contribute:

We run this project as transparently as possible, so you can:

• read and participate in GitHub issues
  
• contribute to our user experience work: sign up to become a member of the UX Studies group (after you join, we'll notify you about future UX surveys and interviews) 
• contact us in the Discourse forum or Zulip chat 
• read our meeting notes

Thank you

Thanks to our contractors on this project: Simply Secure (specifically Georgia Bullen, Bernard Tyers, Nicole Harris, Ngọc Triệu, and Karissa McKelvey), Changeset Consulting (Sumana Harihareswara), Atos (Paul F. Moore), Tzu-ping Chung, Pradyun Gedam, and Ilan Schnell. Thanks also to Ee Durbin at the Python Software Foundation for liaising with the project.

 

This award continues our relationship with Mozilla, which supported Python packaging tools with a Mozilla Open Source Support Award in 2017 for Warehouse. Thank you, Mozilla! (MOSS has a number of types of awards, which are open to different sorts of open source/free software projects. If your project will seek financial support in 2021, do check the MOSS website to see if you qualify.)

This is new funding from the Chan Zuckerberg Initiative. This project is being made possible in part by a grant from the Chan Zuckerberg Initiative DAF, an advised fund of Silicon Valley Community Foundation. Thank you, CZI! (If your free software/open source project is seeking funding and is used by researchers, check the Joint Roadmap for Open Science Tools Rapid Response Fund and consider applying.)

 

The funding for pip's overhaul will end at the end of 2020; if your organization wants to help continue improvements in Python packaging, please join the sponsorship program.

As with all pip releases, a significant amount of the work was contributed by pip's user community. Huge thanks to all who have contributed, whether through code, documentation, issue reports and/or discussion. Your help keeps pip improving, and is hugely appreciated. Thank you to the pip and PyPA maintainers, to the PSF and the Packaging WG, and to all the contributors and volunteers who work on or use Python packaging tools.

 

-Sumana Harihareswara, pip project manager

Upgrade to pip 20.2, plus, changes coming in 20.3

On behalf of the Python Packaging Authority, I am pleased to announce that we have just released pip 20.2, a new version of pip. You can install it by running python -m pip install --upgrade pip.

The highlights for this release are:

- The beta of the next-generation dependency resolver is available -- please test
- Faster installations from wheel files
- Improved handling of wheels containing non-ASCII file contents
- Faster pip list using parallelized network operations
- Installed packages now contain metadata about whether they were directly requested by the user (PEP 376’s REQUESTED file)

The new dependency resolver is off by default because it is in beta and not yet ready for everyday use. The new dependency resolver is significantly stricter and more consistent when it receives incompatible instructions, and reduces support for certain kinds of constraints files, so some workarounds and workflows may break. Please test it with the --use-feature=2020-resolver flag. Please see our guide on how to test and migrate, how to report issues, and context for the change.

Please report bugs through the resolver testing survey.

Thanks to all who tested the alpha of the new resolver in pip 20.1 for feedback that helped us get it to the beta stage.

We are preparing to change the default dependency resolution behavior and make the new resolver the default in pip 20.3 (in October 2020).

This release also partially optimizes pip’s network usage during installation (as part of a Google Summer of Code project by McSinyx). Please test it with pip install --use-feature=2020-resolver --use-feature=fast-deps and report bugs to the issue tracker. This functionality is still experimental and not ready for everyday use.

You can find more details (including deprecations and removals) in the changelog.

As with all pip releases, a significant amount of the work was contributed by pip’s user community. Huge thanks to all who have contributed, whether through code, documentation, issue reports and/or discussion. Your help keeps pip improving, and is hugely appreciated. Specific thanks go to Mozilla (through its Mozilla Open Source Support Awards) and to the Chan Zuckerberg Initiative DAF, an advised fund of Silicon Valley Community Foundation, for their funding that enabled substantial work on the new resolver.

Pip 20.1 has been released

On behalf of the PyPA, I am pleased to announce that a new version of pip, pip 20.1, has been released.

To install pip 20.1, you can run:

python -m pip install --upgrade pip

The highlights for this release are:

• Significant speedups when building local directories, by changing behavior to perform in-place builds, instead of copying to temporary directories.
• Significant speedups in pip list --outdated, by parallelizing network access. This is the first instance of parallel code within pip's codebase.
• A new pip cache command, which makes it possible to introspect and manage pip's cache directory.
• Better pip freeze for packages installed from direct URLs, enabled by the implementation of PEP 610.

This release also contains an alpha version of pip's next generation resolver. It is off by default because it is unstable and not ready for everyday use. If you're curious about this, please visit this GitHub issue about the resolver, what doesn't work yet, and what kind of testing would help us out. We plan to release a version of pip that includes a beta of the new resolver in May.

The full changelog is available.

As with all pip releases, a significant amount of the work was contributed by pip's user community. Huge thanks to all who have contributed, whether through code, documentation, issue reports and/or discussion. Your help keeps pip improving, and is hugely appreciated.

Thank you to the pip and PyPA maintainers, and to all the contributors and volunteers who work on or use Python packaging tools.

And thank you to Mozilla (through its Mozilla Open Source Support Awards) and to the Chan Zuckerberg Initiative DAF, an advised fund of Silicon Valley Community Foundation, for funding enabling work on the new resolver, and thanks to the PSF and the Packaging WG for obtaining and administering that funding.