fix(synthetic): align _SyntheticTextExamplesIterable with HuggingFace…

[arturofredes]

… datasets API

• Add n_shards property (alias of num_shards). HuggingFace IterableDataset expects n_shards; without it, loading synthetic data raises NotImplementedError.
• Change shard_data_sources(worker_id, num_workers) to match the base _BaseExamplesIterable API; the previous signature (num_shards, index, contiguous) caused 'unexpected keyword argument worker_id' when using multiple DataLoader workers. Fixes synthetic data loader when used with datasets.IterableDataset.

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Related Issues

• Resolves #

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[dbutenhof]

Can you tell us what version of the datasets package you're using?

The latest, 4.8.2, aligns with the code in the current GuideLLM. The change you're proposing seems to revert a datasets change made in October 2024, which renamed n_shards to num_shards (although it retained n_shards as an alias for backwards compatibility) and changed the signature of shard_data_sources from what you're proposing to what GuideLLM now uses.

GuideLLM currently depends on the datasets package without any minimum version, but apparently actually depends on a version somewhat later than you're using. (It appears that PR first appeared in datasets 3.1.0.)

Is there another constraint requiring you to use an old version of datasets? And, if not, can you try upgrading?