Change the name to vLLM (#150)
This commit is contained in:
Woosuk Kwon
319
vllm/entrypoints/openai/api_server.py
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319
vllm/entrypoints/openai/api_server.py
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# Adapted from https://github.com/lm-sys/FastChat/blob/168ccc29d3f7edc50823016105c024fe2282732a/fastchat/serve/openai_api_server.py
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import argparse
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from http import HTTPStatus
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import json
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import time
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from typing import AsyncGenerator, Dict, List, Optional
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import fastapi
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from fastapi import BackgroundTasks, Request
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from fastapi.exceptions import RequestValidationError
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from fastapi.middleware.cors import CORSMiddleware
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from fastapi.responses import JSONResponse, StreamingResponse
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import uvicorn
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from vllm.engine.arg_utils import AsyncEngineArgs
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from vllm.engine.async_llm_engine import AsyncLLMEngine
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from vllm.engine.tokenizer_utils import get_tokenizer
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from vllm.entrypoints.openai.protocol import (
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CompletionRequest, CompletionResponse, CompletionResponseChoice,
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CompletionResponseStreamChoice, CompletionStreamResponse, ErrorResponse,
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LogProbs, ModelCard, ModelList, ModelPermission, UsageInfo)
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from vllm.logger import init_logger
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from vllm.outputs import RequestOutput
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from vllm.sampling_params import SamplingParams
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from vllm.utils import random_uuid
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TIMEOUT_KEEP_ALIVE = 5 # seconds
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logger = init_logger(__name__)
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served_model = None
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app = fastapi.FastAPI()
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def create_error_response(status_code: HTTPStatus,
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message: str) -> JSONResponse:
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return JSONResponse(
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ErrorResponse(message=message, type="invalid_request_error").dict(),
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status_code=status_code.value
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)
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@app.exception_handler(RequestValidationError)
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async def validation_exception_handler(request, exc):
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return create_error_response(HTTPStatus.BAD_REQUEST, str(exc))
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async def check_model(request) -> Optional[JSONResponse]:
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if request.model == served_model:
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return
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ret = create_error_response(
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HTTPStatus.NOT_FOUND,
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f"The model `{request.model}` does not exist.",
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)
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return ret
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@app.get("/v1/models")
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async def show_available_models():
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"""Show available models. Right now we only have one model."""
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model_cards = [ModelCard(id=served_model, root=served_model,
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permission=[ModelPermission()])]
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return ModelList(data=model_cards)
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def create_logprobs(token_ids: List[int],
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id_logprobs: List[Dict[int, float]],
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initial_text_offset: int = 0) -> LogProbs:
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"""Create OpenAI-style logprobs."""
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logprobs = LogProbs()
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last_token_len = 0
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for token_id, id_logprob in zip(token_ids, id_logprobs):
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token = tokenizer.convert_ids_to_tokens(token_id)
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logprobs.tokens.append(token)
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logprobs.token_logprobs.append(id_logprob[token_id])
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if len(logprobs.text_offset) == 0:
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logprobs.text_offset.append(initial_text_offset)
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else:
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logprobs.text_offset.append(logprobs.text_offset[-1] + last_token_len)
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last_token_len = len(token)
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logprobs.top_logprobs.append(
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{tokenizer.convert_ids_to_tokens(i): p
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for i, p in id_logprob.items()})
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return logprobs
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@app.post("/v1/completions")
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async def create_completion(raw_request: Request):
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"""Completion API similar to OpenAI's API.
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See https://platform.openai.com/docs/api-reference/completions/create
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for the API specification. This API mimics the OpenAI Completion API.
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NOTE: Currently we do not support the following features:
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- echo (since the vLLM engine does not currently support
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getting the logprobs of prompt tokens)
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- suffix (the language models we currently support do not support
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suffix)
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- logit_bias (to be supported by vLLM engine)
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"""
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request = CompletionRequest(**await raw_request.json())
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logger.info(f"Received completion request: {request}")
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error_check_ret = await check_model(request)
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if error_check_ret is not None:
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return error_check_ret
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if request.echo:
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# We do not support echo since the vLLM engine does not
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# currently support getting the logprobs of prompt tokens.
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return create_error_response(HTTPStatus.BAD_REQUEST,
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"echo is not currently supported")
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if request.suffix is not None:
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# The language models we currently support do not support suffix.
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return create_error_response(HTTPStatus.BAD_REQUEST,
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"suffix is not currently supported")
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if request.logit_bias is not None:
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# TODO: support logit_bias in vLLM engine.
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return create_error_response(HTTPStatus.BAD_REQUEST,
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"logit_bias is not currently supported")
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model_name = request.model
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request_id = f"cmpl-{random_uuid()}"
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prompt = request.prompt
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created_time = int(time.time())
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try:
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sampling_params = SamplingParams(
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n=request.n,
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best_of=request.best_of,
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presence_penalty=request.presence_penalty,
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frequency_penalty=request.frequency_penalty,
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temperature=request.temperature,
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top_p=request.top_p,
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top_k=request.top_k,
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stop=request.stop,
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ignore_eos=request.ignore_eos,
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max_tokens=request.max_tokens,
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logprobs=request.logprobs,
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use_beam_search=request.use_beam_search,
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)
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except ValueError as e:
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return create_error_response(HTTPStatus.BAD_REQUEST, str(e))
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result_generator = engine.generate(prompt, sampling_params,
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request_id)
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# Similar to the OpenAI API, when n != best_of, we do not stream the
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# results. In addition, we do not stream the results when use beam search.
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stream = (request.stream and
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(request.best_of is None or request.n == request.best_of) and
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not request.use_beam_search)
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async def abort_request() -> None:
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await engine.abort(request_id)
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def create_stream_response_json(index: int,
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text: str,
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logprobs: Optional[LogProbs] = None,
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finish_reason: Optional[str] = None) -> str:
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choice_data = CompletionResponseStreamChoice(
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index=index,
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text=text,
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logprobs=logprobs,
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finish_reason=finish_reason,
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)
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response = CompletionStreamResponse(
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id=request_id,
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created=created_time,
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model=model_name,
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choices=[choice_data],
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)
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response_json = response.json(ensure_ascii=False)
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return response_json
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async def completion_stream_generator() -> AsyncGenerator[str, None]:
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previous_texts = [""] * request.n
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previous_num_tokens = [0] * request.n
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async for res in result_generator:
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res: RequestOutput
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for output in res.outputs:
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i = output.index
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delta_text = output.text[len(previous_texts[i]):]
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if request.logprobs is not None:
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logprobs = create_logprobs(
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output.token_ids[previous_num_tokens[i]:],
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output.logprobs[previous_num_tokens[i]:],
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len(previous_texts[i]))
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else:
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logprobs = None
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previous_texts[i] = output.text
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previous_num_tokens[i] = len(output.token_ids)
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response_json = create_stream_response_json(
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index=i,
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text=delta_text,
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logprobs=logprobs,
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)
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yield f"data: {response_json}\n\n"
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if output.finish_reason is not None:
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logprobs = LogProbs() if request.logprobs is not None else None
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response_json = create_stream_response_json(
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index=i,
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text="",
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logprobs=logprobs,
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finish_reason=output.finish_reason,
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)
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yield f"data: {response_json}\n\n"
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yield "data: [DONE]\n\n"
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# Streaming response
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if stream:
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background_tasks = BackgroundTasks()
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# Abort the request if the client disconnects.
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background_tasks.add_task(abort_request)
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return StreamingResponse(completion_stream_generator(),
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media_type="text/event-stream",
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background=background_tasks)
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# Non-streaming response
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final_res: RequestOutput = None
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async for res in result_generator:
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if await raw_request.is_disconnected():
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# Abort the request if the client disconnects.
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await abort_request()
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return create_error_response(HTTPStatus.BAD_REQUEST,
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"Client disconnected")
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final_res = res
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assert final_res is not None
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choices = []
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for output in final_res.outputs:
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if request.logprobs is not None:
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logprobs = create_logprobs(output.token_ids, output.logprobs)
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else:
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logprobs = None
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choice_data = CompletionResponseChoice(
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index=output.index,
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text=output.text,
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logprobs=logprobs,
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finish_reason=output.finish_reason,
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)
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choices.append(choice_data)
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num_prompt_tokens = len(final_res.prompt_token_ids)
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num_generated_tokens = sum(len(output.token_ids)
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for output in final_res.outputs)
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usage = UsageInfo(
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prompt_tokens=num_prompt_tokens,
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completion_tokens=num_generated_tokens,
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total_tokens=num_prompt_tokens + num_generated_tokens,
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)
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response = CompletionResponse(
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id=request_id,
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created=created_time,
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model=model_name,
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choices=choices,
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usage=usage,
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)
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if request.stream:
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# When user requests streaming but we don't stream, we still need to
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# return a streaming response with a single event.
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response_json = response.json(ensure_ascii=False)
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async def fake_stream_generator() -> AsyncGenerator[str, None]:
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yield f"data: {response_json}\n\n"
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yield "data: [DONE]\n\n"
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return StreamingResponse(fake_stream_generator(),
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media_type="text/event-stream")
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return response
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if __name__ == "__main__":
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parser = argparse.ArgumentParser(
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description="vLLM OpenAI-Compatible RESTful API server."
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)
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parser.add_argument("--host", type=str, default="localhost", help="host name")
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parser.add_argument("--port", type=int, default=8000, help="port number")
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parser.add_argument(
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"--allow-credentials", action="store_true", help="allow credentials"
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)
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parser.add_argument(
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"--allowed-origins", type=json.loads, default=["*"], help="allowed origins"
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)
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parser.add_argument(
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"--allowed-methods", type=json.loads, default=["*"], help="allowed methods"
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)
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parser.add_argument(
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"--allowed-headers", type=json.loads, default=["*"], help="allowed headers"
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)
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parser.add_argument("--served-model-name", type=str, default=None,
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help="The model name used in the API. If not specified, "
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"the model name will be the same as the "
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"huggingface name.")
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parser = AsyncEngineArgs.add_cli_args(parser)
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args = parser.parse_args()
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app.add_middleware(
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CORSMiddleware,
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allow_origins=args.allowed_origins,
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allow_credentials=args.allow_credentials,
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allow_methods=args.allowed_methods,
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allow_headers=args.allowed_headers,
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)
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logger.info(f"args: {args}")
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served_model = args.served_model_name or args.model
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engine_args = AsyncEngineArgs.from_cli_args(args)
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engine = AsyncLLMEngine.from_engine_args(engine_args)
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# A separate tokenizer to map token IDs to strings.
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tokenizer = get_tokenizer(args.model)
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uvicorn.run(app, host=args.host, port=args.port, log_level="info",
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timeout_keep_alive=TIMEOUT_KEEP_ALIVE)
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