clean api code, remove redundant background task. (#1102)

vllm/entrypoints/api_server.py

@@ -2,7 +2,7 @@ import argparse
 import json
 from typing import AsyncGenerator
 
-from fastapi import BackgroundTasks, FastAPI, Request
+from fastapi import FastAPI, Request
 from fastapi.responses import JSONResponse, Response, StreamingResponse
 import uvicorn
 
@@ -44,14 +44,8 @@ async def generate(request: Request) -> Response:
             ret = {"text": text_outputs}
             yield (json.dumps(ret) + "\0").encode("utf-8")
 
-    async def abort_request() -> None:
-        await engine.abort(request_id)
-
     if stream:
-        background_tasks = BackgroundTasks()
-        # Abort the request if the client disconnects.
-        background_tasks.add_task(abort_request)
-        return StreamingResponse(stream_results(), background=background_tasks)
+        return StreamingResponse(stream_results())
 
     # Non-streaming case
     final_output = None

vllm/entrypoints/openai/api_server.py

@@ -10,7 +10,7 @@ from typing import AsyncGenerator, Dict, List, Optional, Tuple, Union
 
 import fastapi
 import uvicorn
-from fastapi import BackgroundTasks, Request
+from fastapi import Request
 from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse, StreamingResponse
@@ -229,9 +229,6 @@ async def create_chat_completion(request: ChatCompletionRequest,
     result_generator = engine.generate(prompt, sampling_params, request_id,
                                        token_ids)
 
-    async def abort_request() -> None:
-        await engine.abort(request_id)
-
     def create_stream_response_json(
         index: int,
         text: str,
@@ -291,19 +288,15 @@ async def create_chat_completion(request: ChatCompletionRequest,
 
     # Streaming response
     if request.stream:
-        background_tasks = BackgroundTasks()
-        # Abort the request if the client disconnects.
-        background_tasks.add_task(abort_request)
         return StreamingResponse(completion_stream_generator(),
-                                 media_type="text/event-stream",
-                                 background=background_tasks)
+                                 media_type="text/event-stream")
 
     # Non-streaming response
     final_res: RequestOutput = None
     async for res in result_generator:
         if await raw_request.is_disconnected():
             # Abort the request if the client disconnects.
-            await abort_request()
+            await engine.abort(request_id)
             return create_error_response(HTTPStatus.BAD_REQUEST,
                                          "Client disconnected")
         final_res = res
@@ -448,9 +441,6 @@ async def create_completion(request: CompletionRequest, raw_request: Request):
               and (request.best_of is None or request.n == request.best_of)
               and not request.use_beam_search)
 
-    async def abort_request() -> None:
-        await engine.abort(request_id)
-
     def create_stream_response_json(
         index: int,
         text: str,
@@ -510,19 +500,15 @@ async def create_completion(request: CompletionRequest, raw_request: Request):
 
     # Streaming response
     if stream:
-        background_tasks = BackgroundTasks()
-        # Abort the request if the client disconnects.
-        background_tasks.add_task(abort_request)
         return StreamingResponse(completion_stream_generator(),
-                                 media_type="text/event-stream",
-                                 background=background_tasks)
+                                 media_type="text/event-stream")
 
     # Non-streaming response
     final_res: RequestOutput = None
     async for res in result_generator:
         if await raw_request.is_disconnected():
             # Abort the request if the client disconnects.
-            await abort_request()
+            await engine.abort(request_id)
             return create_error_response(HTTPStatus.BAD_REQUEST,
                                          "Client disconnected")
         final_res = res