Spurious pytest failure

[ritchie46]

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• [X] I have checked that this issue has not already been reported.

• [X] I have confirmed this bug exists on the latest version of Polars.

Issue description

I believe that the the parallelization lead to a race condition with a file.

@stinodego I think we must ensure that all file creators and consumers end up on the same workers.

    @pytest.mark.xfail(sys.platform == "win32", reason="Does not work on Windows")
    def test_parquet_struct_categorical() -> None:
        df = pl.DataFrame(
            [
                pl.Series("a", ["bob"], pl.Categorical),
                pl.Series("b", ["foo"], pl.Categorical),
            ]
        )
        df.write_parquet("/tmp/tmp.pq")
        with pl.StringCache():
>           out = pl.read_parquet("/tmp/tmp.pq").select(pl.col("b").value_counts())

tests/unit/io/test_lazy_parquet.py:207: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
polars/internals/dataframe/frame.py:5603: in select
    self.lazy().select(exprs).collect(no_optimization=True)._df
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <polars.LazyFrame object at 0x7F8EBD9BBDF0>

    def collect(
        self,
        *,
        type_coercion: bool = True,
        predicate_pushdown: bool = True,
        projection_pushdown: bool = True,
        simplify_expression: bool = True,
        no_optimization: bool = False,
        slice_pushdown: bool = True,
        common_subplan_elimination: bool = True,
        streaming: bool = False,
    ) -> pli.DataFrame:
        """
        Collect into a DataFrame.
    
        Note: use :func:`fetch` if you want to run your query on the first `n` rows
        only. This can be a huge time saver in debugging queries.
    
        Parameters
        ----------
        type_coercion
            Do type coercion optimization.
        predicate_pushdown
            Do predicate pushdown optimization.
        projection_pushdown
            Do projection pushdown optimization.
        simplify_expression
            Run simplify expressions optimization.
        no_optimization
            Turn off (certain) optimizations.
        slice_pushdown
            Slice pushdown optimization.
        common_subplan_elimination
            Will try to cache branching subplans that occur on self-joins or unions.
        streaming
            Run parts of the query in a streaming fashion (this is in an alpha state)
    
        Returns
        -------
        DataFrame
    
        Examples
        --------
        >>> df = pl.DataFrame(
        ...     {
        ...         "a": ["a", "b", "a", "b", "b", "c"],
        ...         "b": [1, 2, 3, 4, 5, 6],
        ...         "c": [6, 5, 4, 3, 2, 1],
        ...     }
        ... ).lazy()
        >>> df.groupby("a", maintain_order=True).agg(pl.all().sum()).collect()
        shape: (3, 3)
        ┌─────┬─────┬─────┐
        │ a   ┆ b   ┆ c   │
        │ --- ┆ --- ┆ --- │
        │ str ┆ i64 ┆ i64 │
        ╞═════╪═════╪═════╡
        │ a   ┆ 4   ┆ 10  │
        │ b   ┆ 11  ┆ 10  │
        │ c   ┆ 6   ┆ 1   │
        └─────┴─────┴─────┘
    
        """
        if no_optimization:
            predicate_pushdown = False
            projection_pushdown = False
            slice_pushdown = False
            common_subplan_elimination = False
    
        if streaming:
            common_subplan_elimination = False
    
        ldf = self._ldf.optimization_toggle(
            type_coercion,
            predicate_pushdown,
            projection_pushdown,
            simplify_expression,
            slice_pushdown,
            common_subplan_elimination,
            streaming,
        )
>       return pli.wrap_df(ldf.collect())
E       exceptions.NotFoundError: b
E       
E       > Error originated just after operation: '  DF ["name", "amount"]; PROJECT */2 COLUMNS; SELECTION: "None"
E       '
E       This operation could not be added to the plan.

polars/internals/lazyframe/frame.py:1147: NotFoundError

Reproducible example

None

Expected behavior

Run tests successfully.

Installed versions

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