[bugfix] spec decode worker get tp group only when initialized (vllm-project#13578)

Signed-off-by: Louis Ulmer <[email protected]>

Author: simon-mo

vllm/spec_decode/spec_decode_worker.py

@@ -12,6 +12,7 @@
 from vllm.distributed.communication_op import (broadcast_tensor_dict,
                                                get_tp_group,
                                                tensor_model_parallel_gather)
+from vllm.distributed.parallel_state import model_parallel_is_initialized
 from vllm.logger import init_logger
 from vllm.model_executor.layers.rejection_sampler import RejectionSampler
 from vllm.model_executor.layers.sampler import SamplerOutput
@@ -366,8 +367,12 @@ def init_device(self) -> None:
                 target_lm_head_weight)
 
         self._metrics.init_tensors(self.rank, device_type=self.device)
-        self.spec_decode_sampler.init_tensors(get_tp_group().local_rank,
-                                              device_type=self.device)
+        if model_parallel_is_initialized():
+            self.spec_decode_sampler.init_tensors(get_tp_group().local_rank,
+                                                  device_type=self.device)
+        else:
+            self.spec_decode_sampler.init_tensors(self.rank,
+                                                  device_type=self.device)
 
         scorer_cls: Type[SpeculativeScorer]
         if self.disable_mqa_scorer: