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Streaming Data Pipeline Optimization
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Streaming Data Pipeline Optimization

HardPython

Problem

Optimize a Python-based data pipeline to handle massive streaming inputs for model fine-tuning.

Implement pack_stream(records, block_size, eos_token). Process records in order, keep only the first record for each id, append eos_token after every non-empty accepted record, and return complete fixed-size token blocks. Discard any incomplete final block. The function must return a list of lists, not a generator.

records is a list of dictionaries with integer id and integer-list tokens; block_size is a positive integer. Preserve token order and do not add an EOS token for empty or duplicate records.

Constraints

  • 1 <= block_size
  • 0 <= len(records) <= 5000
  • Each record contains an integer id and a list of integer tokens
  • The total number of input tokens can be large
  • Only the first record for each id is processed
  • Only complete blocks are returned

Function Signature

def pack_stream(records, block_size, eos_token):
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