Fix flaky test timeout test_end_drains_result_queue_to_avoid_join_deadlock on Python 3.14

[FrankYang0529]

Why

• Python 3.14 changed the default multiprocessing start method on Linux from fork to forkserver.

  • https://docs.python.org/3.14/whatsnew/3.14.html#multiprocessing

• With fork, the child is "effectively identical to the parent process" and inherits the already-imported airflow modules. With forkserver it is forked from a clean server process instead. The child must import the test module and related airflow import chain.

  • https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods

• From run 28801030578, both Postgres and Sqlite failed on the same test case test_end_drains_result_queue_to_avoid_join_deadlock with Python 3.14. Both took around 10 seconds to load modules.

  2026-07-06T15:37:46.9780300Z 2026-07-06T15:24:31.594329Z [info     ] Shutting down LocalExecutor; waiting for running tasks to finish.  Signal again if you don't want to wait. [airflow.executors.local_executor.LocalExecutor]
  2026-07-06T15:37:46.9782155Z 2026-07-06T15:24:38.789986Z [info     ] Unit test configuration loaded from 'unit_tests.cfg' [airflow.sdk.configuration] loc=configuration.py:247
  2026-07-06T15:37:46.9784010Z 2026-07-06T15:24:41.043595Z [warning  ] FileType is deprecated. Simply open files after parsing arguments. [py.warnings] category=PendingDeprecationWarning filename=/opt/airflow/airflow-core/src/airflow/cli/cli_config.py lineno=646
  2026-07-06T15:37:46.9786186Z 2026-07-06T15:24:41.045115Z [warning  ] FileType is deprecated. Simply open files after parsing arguments. [py.warnings] category=PendingDeprecationWarning filename=/opt/airflow/airflow-core/src/airflow/cli/cli_config.py lineno=868
  

  2026-07-06T16:23:12.8193184Z 2026-07-06T15:24:18.524457Z [info     ] Shutting down LocalExecutor; waiting for running tasks to finish.  Signal again if you don't want to wait. [airflow.executors.local_executor.LocalExecutor]
  2026-07-06T16:23:12.8195400Z 2026-07-06T15:24:26.279040Z [info     ] Unit test configuration loaded from 'unit_tests.cfg' [airflow.sdk.configuration] loc=configuration.py:247
  2026-07-06T16:23:12.8200174Z 2026-07-06T15:24:28.560555Z [warning  ] FileType is deprecated. Simply open files after parsing arguments. [py.warnings] category=PendingDeprecationWarning filename=/opt/airflow/airflow-core/src/airflow/cli/cli_config.py lineno=646
  2026-07-06T16:23:12.8203506Z 2026-07-06T15:24:28.562044Z [warning  ] FileType is deprecated. Simply open files after parsing arguments. [py.warnings] category=PendingDeprecationWarning filename=/opt/airflow/airflow-core/src/airflow/cli/cli_config.py lineno=868
  

• Other failed run:

  • https://github.com/apache/airflow/actions/runs/28804860689
  • https://github.com/apache/airflow/actions/runs/28709201804
  • https://github.com/apache/airflow/actions/runs/28667462421

How

Change the test's execution_timeout from 10s to 30s. Align it with test_clean_stop_on_signal in the same file, which also spawns a subprocess.

• related: Drain result_queue in LocalExecutor to prevent process join deadlock #67881

---

Was generative AI tooling used to co-author this PR?

• Yes - Claude Code

---

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[Lee-W]

Hey, I think it's been solved by #69538 instead. could you please check and confirm whehter my understanding is correct? Thanks!

[FrankYang0529]

Yes, that is correct. Let me close my PR.