Name of Failure:

Benchmark CI (asv) fails with a wheel-cache collision

Link to task:

https://github.com/mongodb-labs/mongo-arrow/actions/runs/30868793774/job/91866252625

Context of when and why the failure occurred:

First observed in PR #420, a routine Dependabot GitHub Actions bump unrelated to the benchmark suite. Checked the last 10 runs of the Python Benchmark workflow going back to June: this exact failure has occurred on every run since 2026-06-30 (5 consecutive occurrences over roughly 5 weeks), so it is not a one-off flake but a persistent, 100% reproducible break in the benchmark check. Earlier failures in the same job (2026-06-10, 2026-06-26) had different error signatures, so the build (ubuntu-22.04, 3.10) benchmark job has effectively had no passing run in over a month.

The just benchmark-ci step runs asv continuous, which builds and installs the project for both the base and head commits into a shared cache directory. asv finds more than one wheel already present for the same commit SHA in its build cache and cannot choose between them, so the build fails before any benchmarks run.

Stack trace:

·· Building e3c468a8 for virtualenv-py3.13-N_DOCS1000
·· Installing e3c468a8 into virtualenv-py3.13-N_DOCS1000
·· Last error: Found multiple wheels in f/home/runner/work/mongo-arrow/mongo-arrow/bindings/python/env/318905492bd624cc13874949d378ab4a/asv-build-cache/e3c468a8c58c9f990e5991d080068af08ff4b616. Cannot decide correct one
·· Failed to build the project and import the benchmark suite.
error: recipe benchmark-ci failed on line 28 with exit code 1
##[error]Process completed with exit code 1.