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

python/sglang/srt/model_executor/cuda_graph_runner.py

@@ -264,7 +264,7 @@ class CudaGraphRunner:
         if self.enable_torch_compile:
             set_torch_compile_config()
 
-        if self.model_runner.server_args.lora_paths is not None:
+        if self.model_runner.server_args.enable_lora:
             self.model_runner.lora_manager.init_cuda_graph_batch_info(self.max_bs)
 
         # Graph inputs
@@ -510,11 +510,10 @@ class CudaGraphRunner:
                 spec_info.capture_hidden_mode if spec_info else CaptureHiddenMode.NULL
             )
 
-        if self.model_runner.server_args.lora_paths is not None:
-            # Currently, if the lora_path in `lora_paths` is None, the lora backend will use a
-            # different logic to handle lora, so we need to set `lora_paths` to a list of non-None
-            # values if lora is enabled.
-            lora_paths = [next(iter(self.model_runner.server_args.lora_paths))] * bs
+        if self.model_runner.server_args.enable_lora:
+            # It is safe to capture CUDA graph using empty LoRA path, as the LoRA kernels will always be launched whenever
+            # `--enable-lora` is set to True (and return immediately if the LoRA path is empty for perf optimization).
+            lora_paths = [None] * bs
         else:
             lora_paths = None