Support start up LoRA server without initial adapters (#8019)

python/sglang/srt/model_executor/model_runner.py

@@ -304,11 +304,7 @@ class ModelRunner:
             self.apply_torch_tp()
 
         # Init lora
-        # TODO (lifuhuang): when we support dynamic LoRA loading / unloading, we should add
-        # a new server arg `enable_lora` to control whether to init LoRA manager to be more
-        # explicit, as it is perfectly valid to start a server with an empty lora_paths and
-        # load LoRA adapters dynamically later.
-        if server_args.lora_paths is not None:
+        if server_args.enable_lora:
             self.init_lora_manager()
 
         # Init memory pool and attention backends
@@ -895,7 +891,7 @@ class ModelRunner:
             max_lora_rank=self.server_args.max_lora_rank,
             target_modules=self.server_args.lora_target_modules,
         )
-        result = self.lora_manager.load_lora_adapters(self.server_args.lora_paths)
+        result = self.lora_manager.load_lora_adapters(self.server_args.lora_paths or {})
         if result.success:
             logger.info(
                 f"LoRA manager ready. Loaded LoRA adapters: {', '.join(result.loaded_adapters)}"