Add empty side_inputs tuple to MaybeReshuffle PTransform

[liferoad]

Fixes #33854

My guess is MaybeReshuffle is nested and somehow side_inputs is not populated from https://github.com/apache/beam/blob/master/sdks/python/apache_beam/transforms/ptransform.py#L351

Add side_inputs explicitly for MaybeReshuffle.

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[gemini-code-assist]

Summary of Changes

Hello @liferoad, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a targeted fix to the Apache Beam Python SDK, specifically within the MaybeReshuffle PTransform. The change ensures that the side_inputs attribute is always initialized, even if empty, which resolves a potential bug where this attribute could be undefined in certain nested scenarios. This enhancement improves the robustness and reliability of data processing pipelines that utilize this transform.

Highlights

• MaybeReshuffle PTransform: An empty side_inputs tuple has been explicitly added to the MaybeReshuffle PTransform class. This change addresses an issue where side_inputs might not be correctly populated when MaybeReshuffle is nested, preventing potential runtime errors and ensuring consistent behavior.

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[github-actions]

Assigning reviewers:

R: @claudevdm for label python.

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[claudevdm]

I wonder if it is because MaybeReshuffle is defined dynamically (inside Create.expand?) which is affecting the inheritince.

In general I think it is better to avoid dynamic types unless necessary. What do you think about moving MaybeReshuffle to the top level?

[liferoad]

I think we should keep this for now. Not sure changing this will cause any graph compatibility issue.

[claudevdm]

I think any change in this file that adds extra lines breaks update compat unfortunately since this is a nested transform, without explicit labels. See #34807

Line number gets added to the automatically generated label

[shunping]

I remembered I saw this kind of compat issue before. Do we also want to add a label for this change too?

[damccorm]

Do we also want to add a label for this change too?

I think we should do this and deal with the one-time update compat change. I don't think we can be in a place where we can't update this (pretty important) file

We can document this in CHANGES.md and give people a clear update path (via transform_name_mapping)

[damccorm]

Oh I see - we can do even better by explicitly naming it like https://github.com/apache/beam/pull/34807/files

[shunping]

Also notice the original issue is for Beam 2.62. I am not sure if it still happens after we switch to cloudpickle.

[liferoad]

Also notice the original issue is for Beam 2.62. I am not sure if it still happens after we switch to cloudpickle.

Good point.