🐛 fix(deps): drop chardet for req file decoding#3820
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gaborbernat merged 2 commits intotox-dev:mainfrom Feb 24, 2026
Merged
🐛 fix(deps): drop chardet for req file decoding#3820gaborbernat merged 2 commits intotox-dev:mainfrom
gaborbernat merged 2 commits intotox-dev:mainfrom
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gaborbernat
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chardet v6 has critical performance regressions (chardet/chardet#321) causing test pipelines to slow down by orders of magnitude. Replace chardet with BOM detection and UTF-8 decoding with locale fallback, matching pip's own `_decode_req_file` implementation.
ssbarnea
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Feb 25, 2026
Avoids critical bug tox-dev/tox#3820 related to newer chardet, older versions might still bring the buggy version and this one no longer lists it as a dependency. Fixes collection pipeline which was getting stuck due to this bug.
sergei-maertens
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Mar 9, 2026
See tox-dev/tox#3820 - chardet 6 was indeed causing massive performance regressions. Tox 4.46+ does not rely on it any longer.
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chardet v6 introduced critical performance regressions (chardet/chardet#321) that cause test pipelines to slow down by orders of magnitude — tests going from ~0.2s to ~70s each. Since tox 4.45.0 requires
chardet>=6.0.0.post1, this forces all users onto the broken version. Fixes #3818.The
chardetlibrary was only used in one place: detecting the encoding of requirements files viachardet.detect(). This is replaced with BOM detection and UTF-8 decoding with a locale-based fallback, matching pip's own_decode_req_fileimplementation. This handles UTF-8, UTF-16, and UTF-32 (with BOM) and falls back to the system locale encoding for non-UTF-8 files — the same strategy pip uses to read requirements files.This removes
chardetfrom the dependency tree entirely, eliminating the performance regression and reducing tox's install footprint.