message: Don't asynchronously memset dense buffer in AsyncReader constructor
diff: @@ -81,15 +81,13 @@ AsyncReader<SparseType>::AsyncReader(std::string fname, size_t batch_size, size_
  // zero-initialization
  for (size_t i = 0; i < resource_manager_->get_local_gpu_count(); i++) {
  const auto local_gpu = resource_manager_->get_local_gpu(i);
  + CudaDeviceContext ctx(local_gpu->get_device_id());
  if (mixed_precision_) {
  Tensor2<__half> tensor = Tensor2<__half>::stretch_from(dense_tensors_[i]);
  - HCTR_LIB_THROW(cudaMemsetAsync(tensor.get_ptr(), 0,
  - tensor.get_num_elements() * sizeof(__half),
  - local_gpu->get_memcpy_stream()));
  + HCTR_LIB_THROW(cudaMemset(tensor.get_ptr(), 0, tensor.get_num_elements() * sizeof(__half)));
  } else {
  Tensor2<float> tensor = Tensor2<float>::stretch_from(dense_tensors_[i]);
  - HCTR_LIB_THROW(cudaMemsetAsync(tensor.get_ptr(), 0, tensor.get_num_elements() * sizeof(float),
  - local_gpu->get_memcpy_stream()));
  + HCTR_LIB_THROW(cudaMemset(tensor.get_ptr(), 0, tensor.get_num_elements() * sizeof(float)));
  }
  }
  