Fix SecretCache import error in Python 3.14 with pytest-xdist

[amoghrajesh]

---

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We noticed this recently and couple more times, one example: https://github.com/apache/airflow/actions/runs/23764195368/job/69256787158

Error:

FAILED task-sdk/tests/task_sdk/execution_time/test_context_cache.py::TestVariableCacheIntegration::test_delete_variable_invalidates_cache - multiprocessing.managers.RemoteError: 
---------------------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/python/lib/python3.14/multiprocessing/managers.py", line 257, in serve_client
    request = recv()
  File "/usr/python/lib/python3.14/multiprocessing/connection.py", line 257, in recv
    return _ForkingPickler.loads(buf.getbuffer())
           ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/opt/airflow/task-sdk/src/airflow/sdk/execution_time/cache.py", line 24, in <module>
    from airflow.sdk.configuration import conf
ImportError: cannot import name 'conf' from 'airflow.sdk.configuration' (/opt/airflow/task-sdk/src/airflow/sdk/configuration.py)

Turns out that when running tests with pytest-xdist parallel execution for py 3.14, the multiprocessing manager subprocess fails to import the cache module due to a module-level timezone import that triggers conf initialization via __getattr__. In this specific subprocess context, the lazy module-level __getattr__ mechanism does not work too reliably.

I have a fix that moves the timezone import from module-level to method-level
within _CacheValue.__init__() and is_expired(). This ensures that -

1. The cache module can be imported without triggering
   the conf import chain
2. The timezone functionality still works when _CacheValue is actually
   instantiated
3. No behavioral changes to the cache functionality
4. Tests pass both serially and with pytest-xdist parallel execution

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[jason810496]

Base on the PR description, haven't it already been solved in #64501 ?

[jason810496]

I just double-checked the timezone module and it make sense to. use lazy import as timezone module also import the conf.

airflow/task-sdk/src/airflow/sdk/timezone.py

Lines 19 to 33 in 28e08fc

	# We don't want to `import *` here to avoid the risk of making adding too much to Public python API
	from airflow.sdk._shared.timezones.timezone import (
	coerce_datetime,
	convert_to_utc,
	datetime,
	initialize,
	make_naive,
	parse,
	utc,
	utcnow,
	)
	try:
	from airflow.sdk.configuration import conf

[amoghrajesh]

Yes it was transitively importing it

[amoghrajesh]

Failing tests being fixed by: #64524

[potiuk]

Indeed. That one is also needed. Cherry-picking

[potiuk]

Cherry-picked #64537