Flaky `test_join_on_expression_conditions` in cudf-polars-polars tests

[TomAugspurger]

#22739 and #22337 have had flaky failures with this test.

https://github.com/rapidsai/cudf/actions/runs/28056663846/job/83094206038?pr=22700 is the run. Here's the traceback:

=================================== FAILURES ===================================
__ test_join_on_expression_conditions[LENGTH(df1.text) = LENGTH(df2.text)-5] ___
[gw1] linux -- Python 3.14.6 /pyenv/versions/3.14.6/bin/python
Traceback (most recent call last):
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/runner.py", line 353, in from_call
    result: TResult | None = func()
                             ~~~~^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/runner.py", line 245, in <lambda>
    lambda: runtest_hook(item=item, **kwds),
            ~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_hooks.py", line 512, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 167, in _multicall
    raise exception
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/logging.py", line 850, in pytest_runtest_call
    yield
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/capture.py", line 900, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 53, in run_old_style_hookwrapper
    return result.get_result()
           ~~~~~~~~~~~~~~~~~^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_result.py", line 103, in get_result
    raise exc.with_traceback(tb)
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 38, in run_old_style_hookwrapper
    res = yield
          ^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 53, in run_old_style_hookwrapper
    return result.get_result()
           ~~~~~~~~~~~~~~~~~^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_result.py", line 103, in get_result
    raise exc.with_traceback(tb)
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 38, in run_old_style_hookwrapper
    res = yield
          ^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 139, in _multicall
    teardown.throw(exception)
    ~~~~~~~~~~~~~~^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/skipping.py", line 268, in pytest_runtest_call
    return (yield)
            ^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 121, in _multicall
    res = hook_impl.function(*args)
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/runner.py", line 179, in pytest_runtest_call
    item.runtest()
    ~~~~~~~~~~~~^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/python.py", line 1720, in runtest
    self.ihook.pytest_pyfunc_call(pyfuncitem=self)
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_hooks.py", line 512, in __call__
    return self._hookexec(self.name, self._hookimpls.copy(), kwargs, firstresult)
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_manager.py", line 120, in _hookexec
    return self._inner_hookexec(hook_name, methods, kwargs, firstresult)
           ~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 167, in _multicall
    raise exception
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/pluggy/_callers.py", line 121, in _multicall
    res = hook_impl.function(*args)
  File "/pyenv/versions/3.14.6/lib/python3.14/site-packages/_pytest/python.py", line 166, in pytest_pyfunc_call
    result = testfunction(**testargs)
  File "/__w/cudf/cudf/polars/py-polars/tests/unit/sql/test_joins.py", line 876, in test_join_on_expression_conditions
    assert len(res) == expected_length
AssertionError: assert 0 == 5
 +  where 0 = len(shape: (0, 2)\n┌───────┬───────┐\n│ text1 ┆ text2 │\n│ ---   ┆ ---   │\n│ str   ┆ str   │\n╞═══════╪═══════╡\n└───────┴───────┘)

[TomAugspurger]

Some more:

• https://github.com/rapidsai/cudf/actions/runs/28260702627/job/83741921669?pr=22337 / cudf-polars-polars-tests / 13.3.0, 3.14, amd64, ubuntu26.04, rtxpro6000, latest-driver, latest-deps
• https://github.com/rapidsai/cudf/actions/runs/28224143908/job/83612000667#logs / cudf-polars-polars-tests / 13.3.0, 3.13, amd64, ubuntu26.04, h100, latest-driver, latest-deps

https://github.com/rapidsai/cudf/actions/runs/28194276461/job/83559048282?pr=22980 (cudf-polars-polars-tests / 13.3.0, 3.14, amd64, ubuntu26.04, rtxpro6000, latest-driver, latest-deps) had a similar failure in py-polars/tests/unit/io/test_iceberg.py::TestIcebergScanIO::test_scan_iceberg_filter_on_partition.

2026-06-25T23:41:09.0595811Z FAILED py-polars/tests/unit/io/test_iceberg.py::TestIcebergScanIO::test_scan_iceberg_filter_on_partition - assert 1 == 2
2026-06-25T23:41:09.0597024Z  +  where 1 = len(shape: (1, 3)\n┌─────┬─────┬─────────────────────┐\n│ id  ┆ str ┆ ts                  │\n│ --- ┆ --- ┆ ---                 │\n│ i32 ┆ str ┆ datetime[μs]        │\n╞═════╪═════╪═════════════════════╡\n│ 2   ┆ 2   ┆ 2023-03-01 19:25:00 │\n└─────┴─────┴─────────────────────┘)
2026-06-25T23:41:09.0598730Z  +    where shape: (1, 3)\n┌─────┬─────┬─────────────────────┐\n│ id  ┆ str ┆ ts                  │\n│ --- ┆ --- ┆ ---                 │\n│ i32 ┆ str ┆ datetime[μs]        │\n╞═════╪═════╪═════════════════════╡\n│ 2   ┆ 2   ┆ 2023-03-01 19:25:00 │\n└─────┴─────┴─────────────────────┘ = functools.partial(<bound method LazyFrame.collect of <LazyFrame at 0x7E26023075C0>>, engine=<cudf_polars.engine.spmd.SPMDEngine object at 0x7e2bf15f7a10>)()
2026-06-25T23:41:09.0600173Z  +      where functools.partial(<bound method LazyFrame.collect of <LazyFrame at 0x7E26023075C0>>, engine=<cudf_polars.engine.spmd.SPMDEngine object at 0x7e2bf15f7a10>) = <LazyFrame at 0x7E26023075C0>.collect

[Matt711]

This came up again here
cudf-polars-polars-tests / 13.3.0, 3.13, amd64, ubuntu26.04, h100, latest-driver, latest-deps

2026-06-26T07:58:58.9448015Z FAILED py-polars/tests/unit/sql/test_joins.py::test_join_on_expression_conditions[LENGTH(df1.text) = LENGTH(df2.text)-5] - assert 0 == 5
2026-06-26T07:58:58.9449473Z  +  where 0 = len(shape: (0, 2)\n┌───────┬───────┐\n│ text1 ┆ text2 │\n│ ---   ┆ ---   │\n│ str   ┆ str   │\n╞═══════╪═══════╡\n└───────┴───────┘)