[jira] [Created] (ARROW-10670) [Python] Make self_destruct and RecordBatchReader work better together

["David Li (Jira)" <ji...@apache.org>]

David Li created ARROW-10670:
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             Summary: [Python] Make self_destruct and RecordBatchReader work better together
                 Key: ARROW-10670
                 URL: https://issues.apache.org/jira/browse/ARROW-10670
             Project: Apache Arrow
          Issue Type: Improvement
          Components: Python
            Reporter: David Li


When reading record batches via IPC, Arrow generally constructs each batch as a single allocation, with each column in the batch composed of slices of that allocation. This doesn't play well with {{to_pandas(self_destruct=True)}} as even though Arrow will release references to each column, those references were just to slices of a larger allocation, so no memory actually gets freed until the end of the conversion - defeating the point.

Reallocating the batches via pa.concat_arrays avoids this but requires a copy. Additionally, it's unclear that pa.concat_arrays is suitable for this purpose. It would be convenient if the record batch readers could (at least in some cases) provide suitably allocated batches (this may be hard, e.g. in Flight, the batches are ultimately based on memory allocated by gRPC). If that's not possible, then at least, we should either guarantee that concat_arrays truly returns a copy, or provide an explicit way to copy arrays.

This came up when trying to integrate self_destruct into PySpark (see SPARK-32953/https://github.com/apache/spark/pull/29818)



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