NumPy Pixi packages

This directory contains definitions for Pixi packages which can be built from the NumPy source code.

Downstream developers can make use of these packages by adding them as Git dependencies in a Pixi workspace.

This is particularly useful when developers need to build NumPy from source (for example, for an ASan-instrumented build), as it does not require any manual clone or build steps. Instead, Pixi will automatically handle both the build and installation of the package.

See scipy#24066 for a full example of downstream use.

Variants

Each package definition is contained in a subdirectory. All package variants include debug symbols.

Currently defined variants:

default

GIL-enabled build.

Usage:

[dependencies]
python = "*"
numpy.git = "https://github.com/numpy/numpy"
numpy.subdirectory = "pixi-packages/default"

See default/pixi.toml if you wish to use python git tip instead.

Tip: you may change fork and add numpy.rev = "<branch or git hash>" to test unmerged PRs.

freethreading

noGIL build.

Usage:

[dependencies]
python-freethreading = "*"
numpy.git = "https://github.com/numpy/numpy"
numpy.subdirectory = "pixi-packages/freethreading"

See freethreading/pixi.toml if you wish to use python git tip instead.

asan

ASan-instrumented build with -Db_sanitize=address.

Usage:

[dependencies]
python.git = "https://github.com/python/cpython"
python.subdirectory = "Tools/pixi-packages/asan"
numpy.git = "https://github.com/numpy/numpy"
numpy.subdirectory = "pixi-packages/asan"

tsan-freethreading

Freethreading TSan-instrumented build with -Db_sanitize=thread.

Usage:

[dependencies]
python.git = "https://github.com/python/cpython"
python.subdirectory = "Tools/pixi-packages/tsan-freethreading"
numpy.git = "https://github.com/numpy/numpy"
numpy.subdirectory = "pixi-packages/tsan-freethreading"

Maintenance

• Keep host dependency requirements up to date

Troubleshooting

TSan builds may crash on Linux with

FATAL: ThreadSanitizer: unexpected memory mapping 0x7977bd072000-0x7977bd500000

To fix it, try reducing mmap_rnd_bits:

$ sudo sysctl vm.mmap_rnd_bits
vm.mmap_rnd_bits = 32  # too high for TSan
$ sudo sysctl vm.mmap_rnd_bits=28  # reduce it
vm.mmap_rnd_bits = 28

Opportunities for future improvement

• More package variants (such as UBSan)
• Support for Windows
• Using a single pixi.toml for all package variants is blocked on pixi#2813
• Consider pinning dependency versions to guard against upstream breakages over time

Known issues

• numpy#30561: default and freethreading recipes must be manually tweaked to compile against cpython git tip; see default/pixi.toml and freethreading/pixi.toml for details.
• pixi#5226: lock file is invalidated on all pixi invocations
• rattler-build#2094: pixi 0.63.0 introduces a regression regarding the license file; please skip it