# SPDX-License-Identifier: Apache-2.0 # SPDX-FileCopyrightText: Copyright contributors to the vLLM project import asyncio import time from collections.abc import AsyncGenerator from http import HTTPStatus from fastapi import Request from vllm.entrypoints.chat_utils import ConversationMessage from vllm.entrypoints.openai.chat_completion.protocol import ( BatchChatCompletionRequest, ChatCompletionResponse, ChatCompletionResponseChoice, ChatMessage, ) from vllm.entrypoints.openai.chat_completion.serving import OpenAIServingChat from vllm.entrypoints.openai.engine.protocol import ( ErrorResponse, RequestResponseMetadata, UsageInfo, ) from vllm.entrypoints.serve.utils.api_utils import get_max_tokens from vllm.inputs import EngineInput from vllm.logger import init_logger from vllm.outputs import RequestOutput from vllm.parser.abstract_parser import Parser from vllm.tokenizers import TokenizerLike from vllm.utils.async_utils import merge_async_iterators from vllm.utils.collection_utils import as_list logger = init_logger(__name__) class OpenAIServingChatBatch(OpenAIServingChat): """Extends OpenAIServingChat with the /v1/chat/completions/batch endpoint. Processes N conversations from a single request concurrently and returns one choice per conversation indexed 0, 1, ..., N-1. """ async def render_batch_chat_request( self, request: BatchChatCompletionRequest, ) -> tuple[list[list[ConversationMessage]], list[EngineInput]] | ErrorResponse: """Validate the model and preprocess a batched chat completion request. Performs engine-aware checks then delegates per-conversation preprocessing to OnlineRenderer, validating the chat template once for the whole batch. Returns: A tuple of (all_conversations, engine_prompts) on success — one entry per conversation — or an ErrorResponse on failure. """ error_check_ret = await self._check_model(request) if error_check_ret is not None: logger.error("Error with model %s", error_check_ret) return error_check_ret if self.engine_client.errored: raise self.engine_client.dead_error renderer = self.online_renderer if not renderer.use_harmony: # Common case: validate the chat template once for the whole batch. error_check_ret = renderer.validate_chat_template( request_chat_template=request.chat_template, chat_template_kwargs=request.chat_template_kwargs, trust_request_chat_template=renderer.trust_request_chat_template, ) if error_check_ret is not None: return error_check_ret parser = renderer.parser tool_dicts: list[dict] | None = None all_conversations: list[list[ConversationMessage]] = [] all_engine_prompts: list[EngineInput] = [] for messages in request.messages: single_request = request.to_chat_completion_request(messages) if renderer.use_harmony: conversation, engine_prompts = renderer._make_request_with_harmony( single_request, should_include_tools=tool_dicts is not None ) else: conversation, engine_prompts = await renderer.preprocess_chat( single_request, messages, default_template=renderer.chat_template, default_template_content_format=renderer.chat_template_content_format, default_template_kwargs=renderer.default_chat_template_kwargs, tool_dicts=tool_dicts, parser=parser, ) all_conversations.append(conversation) all_engine_prompts.append(engine_prompts[0]) return all_conversations, all_engine_prompts async def create_batch_chat_completion( self, request: BatchChatCompletionRequest, raw_request: Request | None = None, ) -> ChatCompletionResponse | ErrorResponse: """Batch Chat Completion endpoint (/v1/chat/completions/batch). Processes N conversations from a single request concurrently and returns one choice per conversation indexed 0, 1, ..., N-1. Streaming, tool use, and beam search are not supported. """ tokenizer = self.renderer.tokenizer assert tokenizer is not None single_requests = [ request.to_chat_completion_request(messages) for messages in request.messages ] parser: Parser | None = None if self.parser_cls is not None: chat_template_kwargs = self._effective_chat_template_kwargs( single_requests[0] ) parser = self.parser_cls( tokenizer, None, # tools chat_template_kwargs=chat_template_kwargs, ) render_result = await self.render_batch_chat_request(request) if isinstance(render_result, ErrorResponse): return render_result all_conversations, engine_prompts = render_result request_id = ( f"chatcmpl-{self._base_request_id(raw_request, request.request_id)}" ) request_metadata = RequestResponseMetadata(request_id=request_id) if raw_request: raw_request.state.request_metadata = request_metadata lora_request = self._maybe_get_adapters(request, supports_default_mm_loras=True) model_name = self.models.model_name(lora_request) data_parallel_rank = self._get_data_parallel_rank(raw_request) max_model_len = self.model_config.max_model_len generators: list[AsyncGenerator[RequestOutput, None]] = [] for i, engine_prompt in enumerate(engine_prompts): sub_request_id = f"{request_id}_{i}" max_tokens = get_max_tokens( max_model_len, request.max_completion_tokens if request.max_completion_tokens is not None else request.max_tokens, self._extract_prompt_len(engine_prompt), self.default_sampling_params, self.override_max_tokens, ) single_request = single_requests[i] sampling_params = single_request.to_sampling_params( max_tokens, self.default_sampling_params ) self._log_inputs( sub_request_id, engine_prompt, params=sampling_params, lora_request=lora_request, ) trace_headers = ( None if raw_request is None else await self._get_trace_headers(raw_request.headers) ) generators.append( self.engine_client.generate( engine_prompt, sampling_params, sub_request_id, lora_request=lora_request, trace_headers=trace_headers, priority=request.priority, data_parallel_rank=data_parallel_rank, reasoning_ended=None, ) ) return await self.chat_completion_full_generator_batch( request, # type: ignore[arg-type] generators, request_id, model_name, all_conversations, tokenizer, request_metadata, parser, ) async def chat_completion_full_generator_batch( self, request: BatchChatCompletionRequest, # type: ignore[override] generators: list[AsyncGenerator[RequestOutput, None]], request_id: str, model_name: str, all_conversations: list[list[ConversationMessage]], tokenizer: TokenizerLike, request_metadata: RequestResponseMetadata, parser: Parser | None = None, ) -> ErrorResponse | ChatCompletionResponse: """Handle batched (non-streaming) chat completions. Fans out N generators (one per conversation in the batch), collects the final output for each, and assembles a single ``ChatCompletionResponse`` whose ``choices`` are indexed 0,...,N-1. Tool-use and streaming are rejected upstream by the ``check_batch_mode`` validator, so neither needs to be handled here. """ created_time = int(time.time()) final_results: dict[int, RequestOutput] = {} try: async for prompt_idx, res in merge_async_iterators(*generators): final_results[prompt_idx] = res except asyncio.CancelledError: return self.create_error_response("Client disconnected") choices: list[ChatCompletionResponseChoice] = [] total_prompt_tokens = 0 total_completion_tokens = 0 for prompt_idx in range(len(generators)): final_res = final_results.get(prompt_idx) if final_res is None: return self.create_error_response( f"No output received from the engine for prompt {prompt_idx}.", err_type="InternalServerError", status_code=HTTPStatus.INTERNAL_SERVER_ERROR, ) assert final_res.prompt_token_ids is not None num_prompt_tokens = len(final_res.prompt_token_ids) if final_res.encoder_prompt_token_ids is not None: num_prompt_tokens += len(final_res.encoder_prompt_token_ids) total_prompt_tokens += num_prompt_tokens total_completion_tokens += sum( len(output.token_ids) for output in final_res.outputs ) for output in final_res.outputs: self._raise_if_error(output.finish_reason, request_id) if request.logprobs and request.top_logprobs is not None: assert output.logprobs is not None, "Did not output logprobs" logprobs = self._create_chat_logprobs( token_ids=output.token_ids, top_logprobs=output.logprobs, num_output_top_logprobs=request.top_logprobs, tokenizer=tokenizer, return_as_token_id=request.return_tokens_as_token_ids, ) else: logprobs = None if parser is not None: reasoning, content, _ = parser.parse( output.text, request=request, # type: ignore[arg-type] model_output_token_ids=output.token_ids, ) if not request.include_reasoning: reasoning = None else: reasoning = None content = output.text role = ( self.response_role if request.add_generation_prompt else request.messages[prompt_idx][-1]["role"] ) message = ChatMessage(role=role, reasoning=reasoning, content=content) if request.echo: conversation = all_conversations[prompt_idx] last_msg_content: str | list[dict[str, str]] = "" if conversation and "content" in conversation[-1]: last_msg_content = conversation[-1]["content"] or "" if isinstance(last_msg_content, list): last_msg_content = "\n".join( msg["text"] for msg in last_msg_content ) message.content = last_msg_content + (message.content or "") choice_data = ChatCompletionResponseChoice( index=prompt_idx, message=message, logprobs=logprobs, finish_reason=output.finish_reason if output.finish_reason else "stop", stop_reason=output.stop_reason, token_ids=( as_list(output.token_ids) if request.return_token_ids else None ), ) choices.append(choice_data) usage = UsageInfo( prompt_tokens=total_prompt_tokens, completion_tokens=total_completion_tokens, total_tokens=total_prompt_tokens + total_completion_tokens, ) request_metadata.final_usage_info = usage choices.sort(key=lambda c: c.index) return ChatCompletionResponse( id=request_id, created=created_time, model=model_name, choices=choices, usage=usage, system_fingerprint=self.system_fingerprint, )