comment the case of spec decode

Signed-off-by: youkaichao <[email protected]>

vllm/attention/backends/abstract.py

@@ -65,11 +65,6 @@ def make_metadata(cls, *args, **kwargs) -> "AttentionMetadata":
     def get_builder_cls() -> Type["AttentionMetadataBuilder"]:
         raise NotImplementedError
 
-    @classmethod
-    def make_metadata_builder(cls, *args,
-                              **kwargs) -> "AttentionMetadataBuilder":
-        return cls.get_builder_cls()(*args, **kwargs)
-
     @staticmethod
     @abstractmethod
     def get_kv_cache_shape(

vllm/worker/cpu_model_runner.py

@@ -154,8 +154,10 @@ def __init__(self,
         self.device = self.runner.device
         self.multi_modal_input_mapper = self.runner.multi_modal_input_mapper
         self.enable_lora = self.runner.lora_config is not None
-        self.att_metadata_builder = self.runner.attn_backend.get_builder_cls()(
-            self)
+        if self.runner.attn_backend is not None:
+            # spec decode (e.g. Medusa) does not have atten backend
+            attn_backend = self.runner.attn_backend
+            self.att_metadata_builder = attn_backend.get_builder_cls()(self)
 
         self.prepare(finished_requests_ids)
 

vllm/worker/model_runner.py

@@ -460,8 +460,10 @@ def __init__(self,
         self.decode_only = True
 
         # Attention metadata inputs.
-        self.attn_metadata_builder = self.attn_backend.make_metadata_builder(
-            weakref.proxy(self))
+        if self.attn_backend is not None:
+            # spec decode (e.g. Medusa) does not have atten backend
+            self.attn_metadata_builder = self.attn_backend.get_builder_cls()(
+                weakref.proxy(self))
 
         # Engine/Model configurations.
         self.chunked_prefill_enabled = (