Nested dictionary/list objects in context are shared across context splits

[ARMmaster17]

Summary

A shallow copy is performed when a context needs to be split into several parts. This works fine if the context is just storing primitive values like integers and strings. This does not work if there are nested structures within the context.

Implementation

https://www.delftstack.com/howto/python/python-copy-dictionary/#deep-copy-with-copy-module-in-python

[ARMmaster17]

In theory this sounds like a problem. Pending a test that can prove this bug exists in the current implementation of the pipeline logic.

[ARMmaster17]

Proposed test for how to verify this bug:

• Create a standalone pipeline.
• Create a step that outputs a list of two DTO objects with a sample field. Set the output mode to split.
• Create a step that sets the sample field of each object to the current value of a counter that measures how many times that step has run.
• Create a verification step that confirms that the values of the sample fields are 1 and 2.