juditnovak opened a new pull request, #59314:
URL: https://github.com/apache/airflow/pull/59314
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---
closes: https://github.com/apache/airflow/issues/59074
The issue have been demonstrated on separate branch (including helper code
that is not to be merged): https://github.com/juditnovak/airflow/pull/2
The fix have been demonstrated to respond to the issue (including helper
code that is not to be merged): https://github.com/juditnovak/airflow/pull/1
## Root cause
The `dag.test()` function is using a single session throughout its lifetime.
Since data is cached on the session, outdated results are retrieved.
1. LocalExecutor executes workloads via the
[supervisor](https://github.com/apache/airflow/blob/main/task-sdk/src/airflow/sdk/execution_time/supervisor.py)
2. at the end of the task execution, the supervisor is sending an call to
the Airflow API /execution/task-instances/ endpoint. This call is responsible
for updating the database with the final state
4. then the supervisor returns results to the Executor, who will register
the results in its Event Buffer
5. NOTE: 1.)-3.) were part of the Executor's heartbeat()/sync() calls.
6. in the particularly intense dag.test() polling workflow the
SchedulerJobRunner.process_executor_events() call is invoked right after,
rapidly processing contents of the Executor's Event Buffer.
7. however, at this point DB updates from API call from 2.) are not yet
available on the `dag.test()` session. Instead a **cached** record is returned
from an earlier update.
## Testing
- Currently I find not tests within the `task-sdk` targeting `dag.test()`. I
don't know if this may be intentional?
- I find [a single Airflow unit
test](https://github.com/apache/airflow/blob/main/airflow-core/tests/unit/core/test_impersonation_tests.py)
directly relying on the `use_executor=True` option
- it is not the target of the tests, but a tool to perform other tests
- In the supplementary material to this PR I'm providing showcase to the
fix. However since the issue is related to cache expiration, I'm afraid it
would be hard to reproduce with determinisic (i.e. 'non-flaky') tests.
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