Make --loading_phase_threads default to the number of CPUs.

Change the behavior of the --loading_phase_threads to match that of --jobs:
default it to a new "auto" magic value that causes Bazel to determine a
reasonable setting (currently the number of CPUs) but allow users to override
it with an explicit count.

This should alleviate threading contention during analysis and reduce the
unresponsiveness of macOS when this happens.  Some tests on large apps show
a reduction of up to 40% (!) on a MacBook Pro with 4 physical cores and a
more modest 15% on a Mac Pro with 6 physical cores.

Note that the previous hack to cap the number of threads to 20 for unit and
integration tests remains.  I'll tackle this separately.

RELNOTES: --loading_phase_threads now defaults to "auto" (not 200, as was
previously the case), which at the moment corresponds to the number of CPUs.
If your sources are on a slow file system, increasing this value may yield
better analysis-time performance when disk caches are cold.
PiperOrigin-RevId: 215151994
3 files changed
tree: b141aeecb49d525f892669c676ee1bbab33ba080
  1. .bazelci/
  2. examples/
  3. scripts/
  4. site/
  5. src/
  6. third_party/
  7. tools/
  8. .gitattributes
  9. .gitignore
  10. AUTHORS
  11. BUILD
  12. CHANGELOG.md
  13. CODEOWNERS
  14. combine_distfiles.py
  15. combine_distfiles_to_tar.sh
  16. compile.sh
  17. CONTRIBUTING.md
  18. CONTRIBUTORS
  19. distdir.bzl
  20. ISSUE_TEMPLATE.md
  21. LICENSE
  22. README.md
  23. WORKSPACE
README.md

Bazel

{Fast, Correct} - Choose two

Build and test software of any size, quickly and reliably.

  • Speed up your builds and tests: Bazel only rebuilds what is necessary. With advanced local and distributed caching, optimized dependency analysis and parallel execution, you get fast and incremental builds.

  • One tool, multiple languages: Build and test Java, C++, Android, iOS, Go, and a wide variety of other language platforms. Bazel runs on Windows, macOS, and Linux.

  • Scalable: Bazel helps you scale your organization, codebase, and continuous integration solution. It handles codebases of any size, in multiple repositories or a huge monorepo.

  • Extensible to your needs: Easily add support for new languages and platforms with Bazel's familiar extension language. Share and re-use language rules written by the growing Bazel community.

Getting Started

Documentation

Contributing to Bazel

See CONTRIBUTING.md

Build status

Bazel is released in ‘Beta’. See the product roadmap to learn about the path toward a stable 1.0 release.