HuggingFace | PipelineException: No mask_token (<mask>) found on the input - python-3.x

Question

Goal: to for-loop over multiple models, print() elapsed time.
Processing one Model works fine:
i=0
start = time.time()
unmasker = pipeline('fill-mask', model=models[i])
unmasker("Hello I'm a [MASK] model.", top_k=1)
end = time.time()
df = df.append({'Model': models[i], 'Time': end-start}, ignore_index=True)
Some weights of the model checkpoint at bert-base-uncased were not used when initializing BertForMaskedLM: ['cls.seq_relationship.bias', 'cls.seq_relationship.weight']
- This IS expected if you are initializing BertForMaskedLM from the checkpoint of a model trained on another task or with another architecture (e.g. initializing a BertForSequenceClassification model from a BertForPreTraining model).
- This IS NOT expected if you are initializing BertForMaskedLM from the checkpoint of a model that you expect to be exactly identical (initializing a BertForSequenceClassification model from a BertForSequenceClassification model).
However, iterating over many model names causes the titled error.
Code:
from transformers import pipeline
import time
models = ['bert-base-uncased', 'roberta-base', 'distilbert-base-uncased', 'bert-base-cased', 'albert-base-v2', 'roberta-large', 'bert-large-uncased albert-large-v2', 'albert-base-v2', 'bert-large-cased', 'albert-base-v1', 'bert-large-cased-whole-word-masking', 'bert-large-uncased-whole-word-masking', 'albert-xxlarge-v2', 'google/bigbird-roberta-large', 'albert-xlarge-v2', 'albert-xxlarge-v1', 'facebook/muppet-roberta-large', 'facebook/muppet-roberta-base', 'albert-large-v1', 'albert-xlarge-v1']
for _model in models:
start = time.time()
unmasker = pipeline('fill-mask', model=_model)
unmasker("Hello I'm a [MASK] model.", top_k=1) # default: top_k=5
end = time.time()
print(end-start)
Some weights of the model checkpoint at bert-base-uncased were not used when initializing BertForMaskedLM: ['cls.seq_relationship.bias', 'cls.seq_relationship.weight']
- This IS expected if you are initializing BertForMaskedLM from the checkpoint of a model trained on another task or with another architecture (e.g. initializing a BertForSequenceClassification model from a BertForPreTraining model).
- This IS NOT expected if you are initializing BertForMaskedLM from the checkpoint of a model that you expect to be exactly identical (initializing a BertForSequenceClassification model from a BertForSequenceClassification model).
---------------------------------------------------------------------------
PipelineException Traceback (most recent call last)
<ipython-input-19-13b5f651657e> in <module>
3 start = time.time()
4 unmasker = pipeline('fill-mask', model=_model)
----> 5 unmasker("Hello I'm a [MASK] model.", top_k=1) # default: top_k=5
6 end = time.time()
7
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/fill_mask.py in __call__(self, inputs, *args, **kwargs)
224 - **token** (`str`) -- The predicted token (to replace the masked one).
225 """
--> 226 outputs = super().__call__(inputs, **kwargs)
227 if isinstance(inputs, list) and len(inputs) == 1:
228 return outputs[0]
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/base.py in __call__(self, inputs, num_workers, batch_size, *args, **kwargs)
1099 return self.iterate(inputs, preprocess_params, forward_params, postprocess_params)
1100 else:
-> 1101 return self.run_single(inputs, preprocess_params, forward_params, postprocess_params)
1102
1103 def run_multi(self, inputs, preprocess_params, forward_params, postprocess_params):
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/base.py in run_single(self, inputs, preprocess_params, forward_params, postprocess_params)
1105
1106 def run_single(self, inputs, preprocess_params, forward_params, postprocess_params):
-> 1107 model_inputs = self.preprocess(inputs, **preprocess_params)
1108 model_outputs = self.forward(model_inputs, **forward_params)
1109 outputs = self.postprocess(model_outputs, **postprocess_params)
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/fill_mask.py in preprocess(self, inputs, return_tensors, **preprocess_parameters)
82 return_tensors = self.framework
83 model_inputs = self.tokenizer(inputs, return_tensors=return_tensors)
---> 84 self.ensure_exactly_one_mask_token(model_inputs)
85 return model_inputs
86
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/fill_mask.py in ensure_exactly_one_mask_token(self, model_inputs)
76 else:
77 for input_ids in model_inputs["input_ids"]:
---> 78 self._ensure_exactly_one_mask_token(input_ids)
79
80 def preprocess(self, inputs, return_tensors=None, **preprocess_parameters) -> Dict[str, GenericTensor]:
~/anaconda3/envs/pytorch_p36/lib/python3.6/site-packages/transformers/pipelines/fill_mask.py in _ensure_exactly_one_mask_token(self, input_ids)
67 "fill-mask",
68 self.model.base_model_prefix,
---> 69 f"No mask_token ({self.tokenizer.mask_token}) found on the input",
70 )
71
PipelineException: No mask_token (<mask>) found on the input
Please let me know if there's anything else I can add to post to clarify.

Answer 1

Only certain models would throw that error.
Since I am experimenting with runtimes for any model, the below suffices. I was successful at running the majority of models.
I applied try except logic. Note, it is considered bad practice to handle exceptions without naming the error specifically in the except statement.
for _model in models:
for i in range(10):
start = time.time()
try:
unmasker = pipeline('fill-mask', model=_model)
unmasker("Hello I'm a [MASK] model.", top_k=1) # default: top_k=5
print(_model)
except: continue
end = time.time()
df = df.append({'Model': _model, 'Time': end-start}, ignore_index=True)
print(df)
df.to_csv('model_performance.csv', index=False)