Changes/F39ModernizeTBB

Modernize Thread Building Blocks for Fedora 39

This is a proposed Change for Fedora Linux.
This document represents a proposed Change. As part of the Changes process, proposals are publicly announced in order to receive community feedback. This proposal will only be implemented if approved by the Fedora Engineering Steering Committee.

Summary

Fedora is currently shipping version 2020.3 (released July 10, 2020) of the Thread Building Blocks library. The current upstream version is 2021.8 (released December 22, 2022). The Fedora community has expressed interest in moving the TBB package to track a more modern version of the upstream.

Owner

• Name: Thomas Rodgers
• Email: trodgers@redhat.com

Current status

• Targeted release: Fedora 39
• Last updated: 2023-02-13
• FESCo issue: <will be assigned by the Wrangler>
• Tracker bug: <will be assigned by the Wrangler>
• Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

Fedora has shipped with version 2020.3 of the Thread Building Blocks library since Fedora 33. The upstream project made a decision to break backward compatibility after that version was released. As packages move to match the upstream's changes it becomes more difficult to defer updating the Fedora packaging for TBB. The situation is further complicated as there are currently a majority of TBB dependent packages which have not been updated to track a new upstream release, as detailed in this analysis on the tracking issue.

This proposal aims to provide a way to modernize the TBB packge version for Fedora while providing stability for those packages which continue to dependent on the older TBB library version.

It will be possible to install both devel and runtime versions of both TBB packages, however the devel compat package for version 2020.3 will require clients to point to a new include path where the legacy headers will be found.

Benefit to Fedora

Fedora 39 will include a current version of Thread Building Blocks (version 2021.8) while continuing to support clients dependent on an older version of TBB (version 2020.3). Fedora will stay relevant as far as Thread Building Blocks clients are concerned.

Scope

• Proposal owners:
  • A compat package based on the current 2020.3 version of the existing TBB package will be created.
  • Evaluate TBB dependent packages to identify those which need to move to the compat version of the TBB package. An initial analysis suggests the majority of current TBB clients will need to move to the compat package.
  • Post a request for rebuilds to fedora-devel
  • Create patches for those packages affected by this change to adjust their includes to point the compat package's headers as necessary, work with affected package owners to update package specs to account for the change.
  • When most packages are done, re-tag all the packages in rawhide.
  • Watch fedora-devel and assist in rebuilding broken TBB clients.

• Other developers:
  • Those who depend on Thread Building Blocks will have to rebuild their packages. Feature owners will alleviate some of this work as indicated above, and will assist those whose packages fail to build in debugging them.

• Release engineering: TODO

• Policies and guidelines: N/A (not needed for this Change)
  • Apart from scope, this is business as usual, so no new policies, no new guidelines.

Upgrade/compatibility impact

• No manual configuration or data migration needed.
• Some impact on other packages needing code changes to rebuild.

How To Test

• No special hardware is needed.
• Parallel install of the 2020.3 TBB compat packages and the updated TBB packages and checking that it does not break other packages.

User Experience

• Expected to remain largely the same.
• Developers building third-party software on Fedora may need to rebuild against the new TBB packages, and may need to adjust their code to either remain on the compat TBB version or move to the new version supplied by the updated TBB package.

Dependencies

Packages that must be rebuilt: & dnf repoquery -s --releasever=rawhide --whatrequires libtbb\* --enablerepo=fedora | sort -u

The tracking issue's analysis suggests that only the following packages will be able to move to a newer TBB -

• fawkes
• gazebo
• opencascade
• pmemkv
• root

While the remaining clients of TBB will need to have their spec's include paths adjusted to use the 2020.3 compat package.

Contingency Plan

• Contingency mechanism: Worst case scenario is to abandon the update and simply ship F39 with the existing TBB package, which is already in rawhide.

Documentation

• Notes on the scope of change, motivation, and likely impacts are in the comments on the tracking issue.
• https://github.com/oneapi-src/oneTBB/releases/tag/v2021.7.0 (Released 2nd October 2022)
• https://github.com/oneapi-src/oneTBB/releases/tag/v2020.3 (Released 10th July 2020)