Hugging Face Local Pipelines

Hugging Face models can be run locally through the HuggingFacePipeline class.

The Hugging Face Model Hub hosts over 120k models, 20k datasets, and 50k demo apps (Spaces), all open source and publicly available, in an online platform where people can easily collaborate and build ML together.

These can be called from LangChain either through this local pipeline wrapper or by calling their hosted inference endpoints through the HuggingFaceHub class. For more information on the hosted pipelines, see the HuggingFaceHub notebook.

To use, you should have the transformers python package installed, as well as pytorch. You can also install xformer for a more memory-efficient attention implementation.

%pip install transformers --quiet

Model Loading

Models can be loaded by specifying the model parameters using the from_model_id method.

from langchain.llms.huggingface_pipeline import HuggingFacePipeline

hf = HuggingFacePipeline.from_model_id(
    model_id="gpt2",
    task="text-generation",
    pipeline_kwargs={"max_new_tokens": 10},
)

They can also be loaded by passing in an existing transformers pipeline directly

from langchain.llms.huggingface_pipeline import HuggingFacePipeline
from transformers import AutoModelForCausalLM, AutoTokenizer, pipeline

model_id = "gpt2"
tokenizer = AutoTokenizer.from_pretrained(model_id)
model = AutoModelForCausalLM.from_pretrained(model_id)
pipe = pipeline("text-generation", model=model, tokenizer=tokenizer, max_new_tokens=10)
hf = HuggingFacePipeline(pipeline=pipe)

Create Chain

With the model loaded into memory, you can compose it with a prompt to form a chain.

from langchain.prompts import PromptTemplate

template = """Question: {question}

Answer: Let's think step by step."""
prompt = PromptTemplate.from_template(template)

chain = prompt | hf

question = "What is electroencephalography?"

print(chain.invoke({"question": question}))

GPU Inference

When running on a machine with GPU, you can specify the device=n parameter to put the model on the specified device. Defaults to -1 for CPU inference.

If you have multiple-GPUs and/or the model is too large for a single GPU, you can specify device_map="auto", which requires and uses the Accelerate library to automatically determine how to load the model weights.

Note: both device and device_map should not be specified together and can lead to unexpected behavior.

gpu_llm = HuggingFacePipeline.from_model_id(
    model_id="gpt2",
    task="text-generation",
    device=0,  # replace with device_map="auto" to use the accelerate library.
    pipeline_kwargs={"max_new_tokens": 10},
)

gpu_chain = prompt | gpu_llm

question = "What is electroencephalography?"

print(gpu_chain.invoke({"question": question}))

Batch GPU Inference

If running on a device with GPU, you can also run inference on the GPU in batch mode.

gpu_llm = HuggingFacePipeline.from_model_id(
    model_id="bigscience/bloom-1b7",
    task="text-generation",
    device=0,  # -1 for CPU
    batch_size=2,  # adjust as needed based on GPU map and model size.
    model_kwargs={"temperature": 0, "max_length": 64},
)

gpu_chain = prompt | gpu_llm.bind(stop=["\n\n"])

questions = []
for i in range(4):
    questions.append({"question": f"What is the number {i} in french?"})

answers = gpu_chain.batch(questions)
for answer in answers:
    print(answer)