Pandas Bug in Chunk Processing: Non-NULL IDs Become NULL During IterationBUG:

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Reproducible Example

import pandas as pd
import numpy as np

# Sample DataFrame
data = {
    'race_id': [1, 1, 2, 2, 3, 3],
    'value': [10, 20, 30, 40, 50, 60]
}
df = pd.DataFrame(data)

# Chunk processing
chunks = np.array_split(df, 2)
for chunk in chunks:
    print(chunk)

Issue Description

Description: I have encountered a critical bug in the chunk processing functionality of pandas. When performing iteration on specific non-NULL IDs, the chunk processing results in those IDs becoming NULL. This issue also causes related values to be recognized as NULL within the DataFrame, leading to incorrect processing

Expected Behavior

Steps to Reproduce:

Perform iteration on a DataFrame with specific non-NULL IDs. Observe that during chunk processing, those IDs become NULL. Related values within the DataFrame are also recognized as NULL, causing incorrect processing. Expected Behavior: The IDs should remain non-NULL during chunk processing, and related values should be processed correctly.

Actual Behavior: The IDs become NULL during chunk processing, and related values are recognized as NULL, leading to incorrect processing.

Additional Context: This bug significantly impacts the reliability of chunk processing in pandas, making it difficult to perform accurate data analysis. A prompt resolution would be greatly appreciated.

Installed Versions