bugfix: check if acc_logprob is defined before H2D copy. (#293)

Author: yjw258

xllm/core/runtime/llm_worker_impl.cpp

@@ -164,7 +164,7 @@ std::optional<ForwardOutput> LLMWorkerImpl::step(
     // beam search kernel
     BeamSearchOutput beam_search_output;
     if (concated_sampling_params.use_beam_search &&
-        inputs.acc_logprob.numel() > 0) {
+        inputs.acc_logprob.defined() && inputs.acc_logprob.numel() > 0) {
       beam_search_output = beam_searcher_->forward(inputs.acc_logprob,
                                                    sample_output.top_tokens,
                                                    sample_output.top_logprobs);

xllm/core/runtime/worker_impl.cpp

@@ -454,8 +454,10 @@ void WorkerImpl::prepare_work_before_execute(
   }
   processed_inputs.concated_sampling_params =
       inputs.concated_sampling_params.to(device_, dtype_);
-  processed_inputs.acc_logprob =
-      inputs.acc_logprob.to(torch::kFloat32).to(device_);
+  if (inputs.acc_logprob.defined()) {
+    processed_inputs.acc_logprob =
+        inputs.acc_logprob.to(torch::kFloat32).to(device_);
+  }
   auto ret = prepare_stream_->synchronize();
 }