T5 Tokenizer requires `protobuf` package

[sanchit-gandhi]

System Info

• transformers version: 4.32.0.dev0
• Platform: macOS-13.5.1-arm64-arm-64bit
• Python version: 3.9.13
• Huggingface_hub version: 0.16.4
• Safetensors version: 0.3.3
• Accelerate version: not installed
• Accelerate config: not found
• PyTorch version (GPU?): not installed (NA)
• Tensorflow version (GPU?): not installed (NA)
• Flax version (CPU?/GPU?/TPU?): not installed (NA)
• Jax version: not installed
• JaxLib version: not installed

Who can help?

@ArthurZucker @sanchit-gandhi

Information

• The official example scripts
• My own modified scripts

Tasks

• An officially supported task in the examples folder (such as GLUE/SQuAD, ...)
• My own task or dataset (give details below)

Reproduction

1. Ensure protobuf is uninstalled:

pip uninstall protobuf

2. Import the T5Tokenizer:

from transformers import T5Tokenizer

tokenizer = T5Tokenizer.from_pretrained("t5-base")

Traceback:

UnboundLocalError                         Traceback (most recent call last)
Cell In[2], line 1
----> 1 tokenizer = T5Tokenizer.from_pretrained("t5-base")

File ~/transformers/src/transformers/tokenization_utils_base.py:1854, in PreTrainedTokenizerBase.from_pretrained(cls, pretrained_model_name_or_path, cache_dir, force_download, local_files_only, token, revision, *init_inputs, **kwargs)
   1851     else:
   1852         logger.info(f"loading file {file_path} from cache at {resolved_vocab_files[file_id]}")
-> 1854 return cls._from_pretrained(
   1855     resolved_vocab_files,
   1856     pretrained_model_name_or_path,
   1857     init_configuration,
   1858     *init_inputs,
   1859     token=token,
   1860     cache_dir=cache_dir,
   1861     local_files_only=local_files_only,
   1862     _commit_hash=commit_hash,
   1863     _is_local=is_local,
   1864     **kwargs,
   1865 )

File ~/transformers/src/transformers/tokenization_utils_base.py:2017, in PreTrainedTokenizerBase._from_pretrained(cls, resolved_vocab_files, pretrained_model_name_or_path, init_configuration, token, cache_dir, local_files_only, _commit_hash, _is_local, *init_inputs, **kwargs)
   2015 # Instantiate tokenizer.
   2016 try:
-> 2017     tokenizer = cls(*init_inputs, **init_kwargs)
   2018 except OSError:
   2019     raise OSError(
   2020         "Unable to load vocabulary from file. "
   2021         "Please check that the provided vocabulary is accessible and not corrupted."
   2022     )

File ~/transformers/src/transformers/models/t5/tokenization_t5.py:194, in T5Tokenizer.__init__(self, vocab_file, eos_token, unk_token, pad_token, extra_ids, additional_special_tokens, sp_model_kwargs, legacy, **kwargs)
    191 self.vocab_file = vocab_file
    192 self._extra_ids = extra_ids
--> 194 self.sp_model = self.get_spm_processor()

File ~/transformers/src/transformers/models/t5/tokenization_t5.py:200, in T5Tokenizer.get_spm_processor(self)
    198 with open(self.vocab_file, "rb") as f:
    199     sp_model = f.read()
--> 200     model_pb2 = import_protobuf()
    201     model = model_pb2.ModelProto.FromString(sp_model)
    202     if not self.legacy:

File ~/transformers/src/transformers/convert_slow_tokenizer.py:40, in import_protobuf()
     38     else:
     39         from transformers.utils import sentencepiece_model_pb2_new as sentencepiece_model_pb2
---> 40 return sentencepiece_model_pb2

UnboundLocalError: local variable 'sentencepiece_model_pb2' referenced before assignment

This is occurring because we do import_protobuf in the init:

transformers/src/transformers/models/t5/tokenization_t5.py

Line 200 in 85cf90a

model_pb2 = import_protobuf()

But import_protobuf is ill-defined in the case that protobuf is not available:

transformers/src/transformers/convert_slow_tokenizer.py

Lines 32 to 40 in cb8e3ee

	def import_protobuf():
	if is_protobuf_available():
	import google.protobuf
	if version.parse(google.protobuf.__version__) < version.parse("4.0.0"):
	from transformers.utils import sentencepiece_model_pb2
	else:
	from transformers.utils import sentencepiece_model_pb2_new as sentencepiece_model_pb2
	return sentencepiece_model_pb2

=> if protobuf is not installed, then sentencepiece_model_pb2 will be un-defined

Has protobuf been made a soft-dependency for T5Tokenizer inadvertently in #24622? Or can sentencepiece_model_pb2 be defined without protobuf?

Expected behavior

Use T5Tokenizer without protobuf

[ArthurZucker]

See the link PR for a fix