[Testing] [Bug]: stuck tests in test_callback_concurrency.py::test_handle_multiple_concurrent_callback_operations

[dhegberg]

Migration from aws/aws-durable-execution-sdk-python-testing#210

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Expected Behavior

All tests are expected to complete successfully

Actual Behavior

test_callback_concurrency.py::test_handle_multiple_concurrent_callback_operations is stuck in some test runs, e.g.:
https://github.com/aws/aws-durable-execution-sdk-python-testing/actions/runs/24797205718/job/72570041619?pr=208

1 out of ~10 runs of the case would get stuck

This could be a bug in the SDK concurrency or callback implementation.

Steps to Reproduce

Run test case: test_callback_concurrency.py::test_handle_multiple_concurrent_callback_operations

SDK Version

1.4.0

Python Version

3.14

Is this a regression?

No

Last Working Version

No response

Additional Context

No response

[zhongkechen]

integration tests sometimes get running forever

e.g. https://github.com/aws/aws-durable-execution-sdk-python/actions/runs/28884206704/job/85680058946?pr=514

[yaythomas]

I think I have a fix for this. Maybe. 2 PRs incoming.

[yaythomas]

#515
#516

The second (516) might fix this.