[Frontend] split run_server into build_server and run_server (#6740)

vllm/entrypoints/openai/api_server.py

@@ -2,6 +2,7 @@ import asyncio
 import importlib
 import inspect
 import re
+import signal
 from contextlib import asynccontextmanager
 from http import HTTPStatus
 from typing import Optional, Set
@@ -213,12 +214,13 @@ def build_app(args):
     return app
 
 
-def run_server(args, llm_engine=None):
+async def build_server(
+    args,
+    llm_engine: Optional[AsyncLLMEngine] = None,
+    **uvicorn_kwargs,
+) -> uvicorn.Server:
     app = build_app(args)
 
-    logger.info("vLLM API server version %s", VLLM_VERSION)
-    logger.info("args: %s", args)
-
     if args.served_model_name is not None:
         served_model_names = args.served_model_name
     else:
@@ -231,19 +233,7 @@ def run_server(args, llm_engine=None):
               if llm_engine is not None else AsyncLLMEngine.from_engine_args(
                   engine_args, usage_context=UsageContext.OPENAI_API_SERVER))
 
-    event_loop: Optional[asyncio.AbstractEventLoop]
-    try:
-        event_loop = asyncio.get_running_loop()
-    except RuntimeError:
-        event_loop = None
-
-    if event_loop is not None and event_loop.is_running():
-        # If the current is instanced by Ray Serve,
-        # there is already a running event loop
-        model_config = event_loop.run_until_complete(engine.get_model_config())
-    else:
-        # When using single vLLM without engine_use_ray
-        model_config = asyncio.run(engine.get_model_config())
+    model_config = await engine.get_model_config()
 
     if args.disable_log_requests:
         request_logger = None
@@ -296,7 +286,8 @@ def run_server(args, llm_engine=None):
         methods = ', '.join(route.methods)
         logger.info("Route: %s, Methods: %s", route.path, methods)
 
-    uvicorn.run(app,
+    config = uvicorn.Config(
+        app,
         host=args.host,
         port=args.port,
         log_level=args.uvicorn_log_level,
@@ -304,7 +295,39 @@ def run_server(args, llm_engine=None):
         ssl_keyfile=args.ssl_keyfile,
         ssl_certfile=args.ssl_certfile,
         ssl_ca_certs=args.ssl_ca_certs,
-                ssl_cert_reqs=args.ssl_cert_reqs)
+        ssl_cert_reqs=args.ssl_cert_reqs,
+        **uvicorn_kwargs,
+    )
+
+    return uvicorn.Server(config)
+
+
+async def run_server(args, llm_engine=None, **uvicorn_kwargs) -> None:
+    logger.info("vLLM API server version %s", VLLM_VERSION)
+    logger.info("args: %s", args)
+
+    server = await build_server(
+        args,
+        llm_engine,
+        **uvicorn_kwargs,
+    )
+
+    loop = asyncio.get_running_loop()
+
+    server_task = loop.create_task(server.serve())
+
+    def signal_handler() -> None:
+        # prevents the uvicorn signal handler to exit early
+        server_task.cancel()
+
+    loop.add_signal_handler(signal.SIGINT, signal_handler)
+    loop.add_signal_handler(signal.SIGTERM, signal_handler)
+
+    try:
+        await server_task
+    except asyncio.CancelledError:
+        print("Gracefully stopping http server")
+        await server.shutdown()
 
 
 if __name__ == "__main__":
@@ -314,4 +337,4 @@ if __name__ == "__main__":
         description="vLLM OpenAI-Compatible RESTful API server.")
     parser = make_arg_parser(parser)
     args = parser.parse_args()
-    run_server(args)
+    asyncio.run(run_server(args))

vllm/scripts.py

 # The CLI entrypoint to vLLM.
 import argparse
+import asyncio
 import os
 import signal
 import sys
@@ -25,7 +26,7 @@ def serve(args: argparse.Namespace) -> None:
     # EngineArgs expects the model name to be passed as --model.
     args.model = args.model_tag
 
-    run_server(args)
+    asyncio.run(run_server(args))
 
 
 def interactive_cli(args: argparse.Namespace) -> None: