support custom weight loader for model runner (#7122)

Co-authored-by: kavioyu <kavioyu@tencent.com>

python/sglang/srt/model_executor/model_runner.py

@@ -93,6 +93,7 @@ from sglang.srt.torch_memory_saver_adapter import TorchMemorySaverAdapter
 from sglang.srt.utils import (
     MultiprocessingSerializer,
     cpu_has_amx_support,
+    dynamic_import,
     enable_show_time_cost,
     get_available_gpu_memory,
     get_bool_env_var,
@@ -761,6 +762,9 @@ class ModelRunner:
         ]
         if load_format == "direct":
             _model_load_weights_direct(self.model, named_tensors)
+        elif load_format in self.server_args.custom_weight_loader:
+            custom_loader = dynamic_import(load_format)
+            custom_loader(self.model, named_tensors)
         elif load_format is None:
             self.model.load_weights(named_tensors)
         else: