Parallelize Python and Windows .NET CI tests

[SteveSandersonMS]

Summary

• run Python tests in two pytest-xdist worker processes
• use file-level scheduling so each module-scoped E2E client and replay proxy remains on one worker
• split the slow Windows/default .NET suite across two isolated CI jobs
• keep xUnit execution serial within each process, avoiding the process-global environment and working-directory races that in-process class parallelism would introduce

Results

Timings from the PR check run:

Leg	Recent baseline	PR check
Python, Ubuntu, default	10.7 min	5.8 min
Python, Windows, default	21.6 min	12.5 min
Python, Windows, in-process	27.4 min	15.8 min
.NET, Windows test step	18.1 min	10.7 min critical shard
.NET, Windows whole job	21.9 min	17.8 min critical shard

The Windows .NET critical job was 17.8 minutes in the PR run because one shard had an anomalous 8.9-minute build; its test step was 7.5 minutes. In the separate all-SDK dispatch, builds were normal and the critical Windows shard completed in 15.4 minutes.

The overall PR workflow took 26.8 minutes because two unchanged Ubuntu .NET backend cells had anomalous 12.4- and 19.9-minute build steps. The same final commit completed the all-SDK dispatch in 16.3 minutes. This change does not parallelize or otherwise modify those Ubuntu cells.

The .NET shard filters cover all 710 discovered tests exactly once, split 355/355. All six SDK workflows passed on the final commit in workflow run 30923106592.

Relationship to #2186

#2186 splits Windows .NET execution by target framework for isolation. This PR splits it by test class for latency. The approaches are complementary; if #2186 merges first, the matrix should compose both dimensions (two frameworks by two test shards).

[Copilot]

Pull request overview

Runs Python CI tests concurrently while preserving module-scoped E2E fixtures and proxies.

Changes:

• Adds pytest-xdist as a development dependency.
• Runs pytest with two workers using file-level scheduling.

Show a summary per file

File	Description
python/pyproject.toml	Adds the parallel-test dependency.
.github/workflows/python-sdk-tests.yml	Enables two-worker, file-scheduled test execution.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Balanced

[github-actions]

SDK Consistency Review ✅

This PR only modifies Python CI test infrastructure:

• Adds pytest-xdist dev dependency for parallel test execution
• Updates the CI workflow to run tests with -n 2 --dist=loadfile

This is Python/pytest-specific tooling with no equivalent needed in other SDKs (each SDK uses its own test runner). No SDK API surface changes were made, so there are no cross-language consistency concerns.

Generated by SDK Consistency Review Agent for #2251 · sonnet46 15.4 AIC · ⌖ 5.35 AIC · ⊞ 6.6K · ◷

[Copilot]

Review details

Suppressed comments (1)

.github/workflows/dotnet-sdk-tests.yml:15

• The PR title, summary, and reported results are scoped entirely to Python/pytest-xdist, but this file also introduces a separate .NET Windows sharding strategy. This makes the .NET behavior an unreported scope change with no shard results to validate it. Please split this change into a dedicated PR, or update the PR description and provide the corresponding .NET validation results.

    name: ".NET SDK Tests (${{ matrix.os }}, ${{ matrix.transport }}, ${{ matrix.backend }}, ${{ matrix.shard }})"

• Files reviewed: 3/3 changed files
• Comments generated: 0 new
• Review effort level: Balanced