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[Data][Flaky] fix test_limit_pushdown_conservative fails due to non-deterministic task ordering #58655

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Merged
bveeramani merged 4 commits into from
Nov 17, 2025
Merged

[Data][Flaky] fix test_limit_pushdown_conservative fails due to non-deterministic task ordering #58655

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77d44d4
Enhance limit pushdown tests with ordering checks
ryankert01 Nov 15, 2025
0aee4a4
Update test_execution_optimizer_limit_pushdown.py
ryankert01 Nov 16, 2025
0a7168d
Remove unnecessary comment in test for optimizer
ryankert01 Nov 16, 2025
1a6a21f
fix imports
ryankert01 Nov 16, 2025
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9 changes: 8 additions & 1 deletion python/ray/data/tests/test_execution_optimizer_limit_pushdown.py
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@
import ray
from ray.data import Dataset
from ray.data._internal.logical.interfaces import Plan
from ray.data._internal.util import rows_same
from ray.data.block import BlockMetadata
from ray.data.datasource import Datasource
from ray.data.datasource.datasource import ReadTask
Expand All @@ -19,8 +20,13 @@ def _check_valid_plan_and_result(
expected_plan: Plan,
expected_result: List[Dict[str, Any]],
expected_physical_plan_ops=None,
check_ordering=True,
):
assert ds.take_all() == expected_result
actual_result = ds.take_all()
if check_ordering:
assert actual_result == expected_result
Comment on lines +26 to +27
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@bveeramani bveeramani Nov 16, 2025

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Any reason we can't always use rows_same (i.e., always use check_ordering=False)? Are there any tests in this file where the ordering is guaranteed by Ray Data's interface?

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@ryankert01 ryankert01 Nov 16, 2025

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I think there's still some need to check ordering, for example test 6 the ordering is guaranteed.

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@bveeramani bveeramani Nov 17, 2025

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Ah, I see. I guess there are a few tests that call sort

In a follow-up PR, would you mind updating all of the other tests in this module where the ordering isn't guaranteed? Seems like most of the tests assume ordering when it's not guaranteed

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@bveeramani bveeramani Nov 17, 2025

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Separately, I think it'd be good to break up the different test cases into separate test functions for the reasons described here: https://learn.microsoft.com/en-us/dotnet/core/testing/unit-testing-best-practices#avoid-multiple-act-tasks

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@ryankert01 ryankert01 Nov 17, 2025

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Cool, I'll open a refactor pr soon!

else:
assert rows_same(pd.DataFrame(actual_result), pd.DataFrame(expected_result))
assert ds._plan._logical_plan.dag.dag_str == expected_plan

expected_physical_plan_ops = expected_physical_plan_ops or []
Expand Down Expand Up @@ -83,6 +89,7 @@ def f2(x):
ds,
"Read[ReadRange] -> Limit[limit=5] -> Project[Project]",
[{"id": i} for i in range(5)],
check_ordering=False,
)

# Test 6: Limit should stop at Sort operations (AllToAll)
Expand Down