[Frontend] Move APIServerProcessManager target server fn (#38115)

Signed-off-by: Nick Hill <nickhill123@gmail.com>

vllm/v1/utils.py

@@ -21,13 +21,14 @@ from typing import (
 )
 
 import torch
+import uvloop
 from torch.autograd.profiler import record_function
 
 import vllm.envs as envs
 from vllm.logger import init_logger
 from vllm.usage.usage_lib import UsageContext, is_usage_stats_enabled, usage_message
 from vllm.utils.network_utils import get_open_port, get_open_zmq_ipc_path, get_tcp_uri
-from vllm.utils.system_utils import kill_process_tree
+from vllm.utils.system_utils import decorate_logs, kill_process_tree, set_process_title
 from vllm.v1.core.sched.output import SchedulerOutput
 
 if TYPE_CHECKING:
@@ -166,20 +167,20 @@ class APIServerProcessManager:
 
     def __init__(
         self,
-        target_server_fn: Callable,
         listen_address: str,
         sock: Any,
         args: argparse.Namespace,
         num_servers: int,
         input_addresses: list[str],
         output_addresses: list[str],
+        target_server_fn: Callable | None = None,
         stats_update_address: str | None = None,
         tensor_queue: Queue | None = None,
     ):
         """Initialize and start API server worker processes.
 
         Args:
-            target_server_fn: Function to call for each API server process
+            target_server_fn: Override function to call for each API server process
             listen_address: Address to listen for client connections
             sock: Socket for client connections
             args: Command line arguments
@@ -212,7 +213,7 @@ class APIServerProcessManager:
                 client_config["tensor_queue"] = tensor_queue
 
             proc = spawn_context.Process(
-                target=target_server_fn,
+                target=target_server_fn or run_api_server_worker_proc,
                 name=f"ApiServer_{i}",
                 args=(listen_address, sock, args, client_config),
             )
@@ -231,6 +232,25 @@ class APIServerProcessManager:
             shutdown(self.processes, timeout=timeout)
 
 
+def run_api_server_worker_proc(
+    listen_address, sock, args, client_config=None, **uvicorn_kwargs
+) -> None:
+    """Entrypoint for individual API server worker processes."""
+
+    from vllm.entrypoints.openai.api_server import run_server_worker
+
+    client_config = client_config or {}
+    server_index = client_config.get("client_index", 0)
+
+    # Set process title and add process-specific prefix to stdout and stderr.
+    set_process_title("APIServer", str(server_index))
+    decorate_logs()
+
+    uvloop.run(
+        run_server_worker(listen_address, sock, args, client_config, **uvicorn_kwargs)
+    )
+
+
 def wait_for_completion_or_failure(
     api_server_manager: APIServerProcessManager,
     engine_manager: Union["CoreEngineProcManager", "CoreEngineActorManager"]