[codex] Speed up local nextest runs - #26479
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Why
just testcurrently uses the CI-oriented nextest profile, which serializes app-server integration tests even on developer machines that can run several safely. Bounded local parallelism substantially shortens this common iteration loop without changing CI behavior.Eight-worker experiments were faster, but keeping them reliable required relaxing several test deadlines. Four workers for integration tests is a solid tradeoff that speeds up local testing without needing to change test logic.
What changed
localnextest profile that inherits the existing defaults.just testselect the local profile on Unix and Windows.The tests use separate processes, randomized temporary
CODEX_HOMEdirectories, and ephemeral ports. The remaining shared constraints are system resources; each app-server also uses a multi-thread Tokio runtime, and fuzzy-search tests can create additional worker threads, so the local cap remains intentionally conservative.Performance and validation
All measurements below are warm, execution-only app-server runs with nextest retries disabled.
On the current rebased branch, an AMD EPYC 7763 machine with 16 logical CPUs and 62 GiB RAM completed three consecutive runs:
The mean wall time was 145.28s. The slow-inventory, approval replay, and zsh-fork tests all passed with their original deadlines.
Earlier measurements on the same Linux machine, before the suite grew, showed the scaling that motivated the change:
Four workers reduced that execution time by about 70%, a roughly 3.3x speedup over serialization.