consolidatewheels 0.3

Introduction

When multiple wheels depend on each other and share some .so files, it is possible to rely on auditwheel --exclude to make sure the .so is included in only one of the wheels to avoid duplicating the file in every package.

That allows Python wheels to share the same .so as far as at least one of them is loading them in memory. See https://github.com/pypa/auditwheel/issues/76 and https://github.com/pypa/auditwheel/pull/368 for discussions on the topic.

The problem with this approach is that the package where the .so is included will have the library name mangled by auditwheel, while the ones where it’s excluded will reference to the library with its original name.

Suppose you have libone.whl and libtwo.whl both depending on libfoo.so, and libone is a dependency of libtwo so you already know you can include libfoo.so only in libone.whl, you could do:

auditwheel repair dist/libone.whl
auditwheel repair dist/libtwo.whl --exclude libfoo.so

In such case you would end up with the following wheels:

venv/lib/python3.10/site-packages/libone
├── __init__.py
├── _libone.cpython-310-aarch64-linux-gnu.so
venv/lib/python3.10/site-packages/libone.libs
└── libfoo-ef63151d.so
venv/lib/python3.10/site-packages/libtwo
├── __init__.py
├── _libtwo.cpython-310-aarch64-linux-gnu.so

The problem would be that while _libone.cpython-310-aarch64-linux-gnu.so was patched by auditwheel to know about the libfoo-ef63151d.so name, _libtwo.cpython-310-aarch64-linux-gnu.so was not, and so still refers to the original name:

$ ldd venv/lib/python3.10/site-packages/libone/_libone.cpython-310-aarch64-linux-gnu.so
    libfoo-ef63151d.so => ../libone.libs/libfoo-ef63151d.so (0x0000ffff8f8f0000)

$ ldd venv/lib/python3.10/site-packages/libtwo/_libtwo.cpython-310-aarch64-linux-gnu.so
    libfoo.so => not found

Which means that trying to import libtwo will fail with:

ImportError: libfoo.so: cannot open shared object file: No such file or directory

Which makes sense, because we actually provided libfoo-ef63151d.so and not libfoo.so.

To solve this problem consolidatewheels will patch all provided wheels to make sure that they share a single naming convention for libraries that were mangled.

After consolidatewheels is used, the final result would be:

$ ldd venv/lib/python3.10/site-packages/libone/_libone.cpython-310-aarch64-linux-gnu.so
    libfoo-ef63151d.so => ../libone.libs/libfoo-ef63151d.so (0x0000ffff8f8f0000)

$ ldd venv/lib/python3.10/site-packages/libtwo/_libtwo.cpython-310-aarch64-linux-gnu.so
    libfoo-ef63151d.so => not found

which would work correctly as far as libone is imported _before_ libtwo as they will both look for libfoo-ef63151d.so which was loaded already by libone.

Install

Install with:

$ pip install consolidatewheels

Note that consolidatewheels requires patchelf to be available in the system, and it only works on Linux systems. But those are the same requirements that auditwheel has, so you are probably already satisfying them if you use auditwheel.

Usage

Usage instructions:

consolidatewheels --help

Example:

consolidatewheels libone.whl libtwo.whl --dest=./consolidated_wheels

For a more complex example and a testing environment, you can take a look at https://github.com/amol-/wheeldeps which uses consolidatewheels