Motivation and Context

All 20 pytest-xdist workers crash with [gwN] node down: Not properly terminated during Azure Functions integration tests on Python 3.13. The python-tests-functions job had a UV_PYTHON: "3.10" override masking this, but the parent workflow sets UV_PYTHON: "3.13", so the override was silently ignored.

Root cause: the function_app_for_test fixture retry loop can spend up to ~184s (3 × 60s wait + cleanup), exceeding the 120s --timeout. When pytest-timeout's thread method fires mid-fixture and the thread is blocked, it calls os._exit() — killing the xdist worker outright. Compounding this, the func subprocess shares the worker's process group, so signals propagate bidirectionally.

Description

conftest.py — subprocess isolation

Added start_new_session=True on Linux so the func start process runs in its own process group. Prevents signal cross-contamination between pytest-timeout and the function host.

# Before
return subprocess.Popen(["func", "start", "--port", str(port)], cwd=str(sample_path), env=env)

# After
return subprocess.Popen(
    ["func", "start", "--port", str(port)],
    cwd=str(sample_path),
    env=env,
    start_new_session=True,
)

conftest.py — fixture timeout budget

Added a 100s overall budget (under the 120s test timeout) that caps each retry's max_wait to the remaining time. The fixture now always exits cleanly via pytest.fail() instead of being killed by os._exit(). Uses time.monotonic() for budget tracking so NTP/clock adjustments cannot skew the enforcement.

Workflow files — remove stale Python 3.10 pin

Removed UV_PYTHON: "3.10" from python-tests-functions in both python-merge-tests.yml and python-integration-tests.yml. The job now inherits the workflow-level UV_PYTHON: "3.13".

Contribution Checklist

• The code builds clean without any errors or warnings
• The PR follows the Contribution Guidelines
• All unit tests pass, and I have added new tests where possible
• Is this a breaking change? If yes, add "[BREAKING]" prefix to the title of the PR.

• Fixes Python: Integration tests failing due to parallel worker crashes in Azure Functions in Py3.13 #4259

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