UV_BUILD_CONCURRENCY not working #15307
Description
Summary
Hi, my goal is to have uv build only a single package at a time to prevent out of memory bugs.
export UV_CONCURRENT_BUILDS=1
uv sync --locked
However uv spawns multiple build processes (bdist_wheel, setuptools)
pstree $$
uv─┬─python───python───python───cmake───ninja───sh───x86_64-linux-gn───cc1plus
├─python───cmake───gmake───gmake───gmake───sh───c++───cc1plus
└─22*[{uv}]
uv self version
uv 0.8.8
uname -a
Linux ubuntu 6.8.0-71-generic #71-Ubuntu SMP PREEMPT_DYNAMIC Tue Jul 22 16:52:38 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux
Am I misunderstanding the setting or might this be a bug?
Platform
Linux 6.8.0-71-generic x86_64 GNU/Linux
Version
uv 0.8.8
Python version
Python 3.12.3