[Bug] Python 3.14 unit tests intermittently stall during pytest shutdown

[RyAuld]

Description

Python 3.14 unit tests intermittently stall after all tests pass (reaches 99-100% completion), hanging until the 5-minute step timeout kills the process. Other Python versions (3.9–3.13) consistently complete in ~1.5 minutes.

Observed Behavior

• All tests pass successfully
• The last output before the stall is typically a deprecation warning or the final test result
• The process hangs during pytest session teardown/finalization
• The stall is intermittent — sometimes Python 3.14 passes, sometimes it hangs

Builds Exhibiting This Issue

• 1651220 — canceled at 30-min timeout
• 1651218 — canceled at 30-min timeout
• 1654753 — failed at 5-min timeout (after timeout was reduced)

Mitigations Already Applied (PR #934)

• Replaced deprecated datetime.utcnow() with datetime.now(timezone.utc) — did not resolve the stall
• Removed 2>&1 | tee pipe (replaced with --log-file) — did not resolve the stall
• Added timeoutInMinutes: 5 on the pytest step to fail fast

Suspected Root Causes

Without agent-level access, we cannot definitively determine the cause. Likely candidates:

1. pytest-azurepipelines plugin — may hang during post-test result upload on 3.14
2. Python 3.14 interpreter shutdown — thread/GC finalization deadlock in pre-release runtime
3. Dependencies compiled from source (no pre-built 3.14 wheels) — buggy atexit/cleanup handler
4. Hosted agent resource contention — network timeout to ADO during result publishing

Suggested Next Steps

• Try running with -p no:azurepipelines to rule out plugin issues
• Add continueOnError: true for Python 3.14 matrix entry to unblock PRs
• Consider removing Python 3.14 from the CI matrix until official release and ecosystem wheel availability
• Revisit once Python 3.14 reaches stable release

[RyAuld]

Resolved in PR #936 — removed pytest-azurepipelines plugin which was causing the intermittent stall during pytest session finalization on Python 3.14.

Verification:

• 3 consecutive CI builds on PR Remove pytest-azurepipelines plugin to fix Python 3.14 stall #936 all passed Python 3.14: builds 1654786, 1654787, 1654788
• PR Migrate region discovery to IMDS /compute JSON endpoint #929 also passed Python 3.14 after picking up the fix (build 1654834)
• Local testing confirmed 304 tests pass in ~51s on Python 3.14 without the plugin

The plugin was unnecessary since --junitxml + PublishTestResults task already handle test result reporting to ADO.