【vLLM 学习】Load Sharded State

vLLM 是一款专为大语言模型推理加速而设计的框架，实现了 KV 缓存内存几乎零浪费，解决了内存管理瓶颈问题。

更多 vLLM 中文文档及教程可访问 →https://vllm.hyper.ai/

*在线运行 vLLM 入门教程：零基础分步指南

源码 examples/offline_inference/load_sharded_state.py.

# SPDX-License-Identifier: Apache-2.0
"""
Validates the loading of a model saved with the sharded_state format.
This script demonstrates how to load a model that was previously saved
using save_sharded_state.py and validates it by running inference.
Example usage:
(First need to save a sharded_state mode)

python save_sharded_state.py \
    --model /path/to/load \
    --quantization deepspeedfp \
    --tensor-parallel-size 8 \
    --output /path/to/save/sharded/modele

python load_sharded_state.py \
    --model /path/to/saved/sharded/model \
    --load-format sharded_state \
    --quantization deepspeedfp \
    --tensor-parallel-size 8 \
    --prompt "Hello, my name is" \
    --max-tokens 50
"""

import dataclasses

from vllm import LLM, EngineArgs, SamplingParams
from vllm.utils import FlexibleArgumentParser


def parse_args():
    parser = FlexibleArgumentParser()
    # Add engine arguments
    EngineArgs.add_cli_args(parser)

    # Override default load_format for clarity
    parser.set_defaults(load_format="sharded_state")

    # Add validation arguments
    parser.add_argument("--prompt",
                        type=str,
                        default="Hello, world!",
                        help="Prompt for validation")
    parser.add_argument("--max-tokens",
                        type=int,
                        default=100,
                        help="Maximum number of tokens to generate")
    parser.add_argument("--temperature",
                        type=float,
                        default=0.7,
                        help="Sampling temperature")
    parser.add_argument("--top-p",
                        type=float,
                        default=1.0,
                        help="Top-p sampling parameter")

    return parser.parse_args()


def main():
    args = parse_args()
    engine_args = EngineArgs.from_cli_args(args)

    print(f"Loading model from {engine_args.model} "
          f"using format {engine_args.load_format}")
    print(f"Tensor parallel size: {engine_args.tensor_parallel_size}")

    # Load the model using engine args
    llm = LLM(**dataclasses.asdict(engine_args))

    # Prepare sampling parameters
    sampling_params = SamplingParams(
        temperature=args.temperature,
        top_p=args.top_p,
        max_tokens=args.max_tokens,
    )

    print("\nRunning inference:")
    print(f"Prompt: {args.prompt}")

    # Generate completion
    outputs = llm.generate(args.prompt, sampling_params)

    # Display generated text
    print("\nGenerated outputs:")
    for output in outputs:
        generated_text = output.outputs[0].text
        print("-" * 50)
        print(f"Full output: {args.prompt}{generated_text}")
        print("-" * 50)


if __name__ == "__main__":
    main()