[jira] [Created] (ARROW-11983) [Python] ImportError calling pyarrow from_pandas within ThreadPool

["Joris Van den Bossche (Jira)" <ji...@apache.org>]

Joris Van den Bossche created ARROW-11983:
---------------------------------------------

             Summary: [Python] ImportError calling pyarrow from_pandas within ThreadPool
                 Key: ARROW-11983
                 URL: https://issues.apache.org/jira/browse/ARROW-11983
             Project: Apache Arrow
          Issue Type: Bug
          Components: Python
            Reporter: Joris Van den Bossche
            Assignee: Joris Van den Bossche
             Fix For: 4.0.0


From https://github.com/dask/dask/issues/7334

The referenced issue report is about an ImportError they get using Python 3.9 (and I can reproduce it). As far as I know how dask works, it's basically calling `pa.Table.from_pandas` within a ThreadPool, and inside `from_pandas` we do a `with futures.ThreadPoolExecutor`, which then fails with this error:

{code}
>>> df2.to_parquet('test99.parquet', engine='pyarrow-dataset')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/dataframe/core.py", line 4127, in to_parquet
    return to_parquet(self, path, *args, **kwargs)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/dataframe/io/parquet/core.py", line 671, in to_parquet
    out = out.compute(**compute_kwargs)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/base.py", line 283, in compute
    (result,) = compute(self, traverse=False, **kwargs)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/base.py", line 565, in compute
    results = schedule(dsk, keys, **kwargs)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/threaded.py", line 76, in get
    results = get_async(
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/local.py", line 487, in get_async
    raise_exception(exc, tb)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/local.py", line 317, in reraise
    raise exc
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/local.py", line 222, in execute_task
    result = _execute_task(task, data)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/core.py", line 121, in _execute_task
    return func(*(_execute_task(a, cache) for a in args))
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/utils.py", line 35, in apply
    return func(*args, **kwargs)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/dataframe/io/parquet/arrow.py", line 841, in write_partition
    t = cls._pandas_to_arrow_table(df, preserve_index=preserve_index, schema=schema)
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/dask/dataframe/io/parquet/arrow.py", line 814, in _pandas_to_arrow_table
    table = pa.Table.from_pandas(df, preserve_index=preserve_index, schema=schema)
  File "pyarrow/table.pxi", line 1479, in pyarrow.lib.Table.from_pandas
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/site-packages/pyarrow/pandas_compat.py", line 596, in dataframe_to_arrays
    with futures.ThreadPoolExecutor(nthreads) as executor:
  File "/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/concurrent/futures/__init__.py", line 49, in __getattr__
    from .thread import ThreadPoolExecutor as te
ImportError: cannot import name 'ThreadPoolExecutor' from partially initialized module 'concurrent.futures.thread' (most likely due to a circular import) (/home/joris/miniconda3/envs/test-dask-pyarrow-bug/lib/python3.9/concurrent/futures/thread.py)
{code}

We can probably avoid that by moving the import top-level (not inline inside dataframe_to_arrays)



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