我在Ubuntu 18.04LTS PyTorch C++(1.5.1，CUDA 10.1(上通过预训练的wordvector(glove.300d(使用torch::Embedding模块计算单词相似度。我相信我已经把我能做的一切都移到了GPU上，但当我执行它时，它仍然会说(问题末尾的完整错误日志(：
Expected object of device type cuda but got device type cpu for
argument #1 'self' in call to _th_index_select
(checked_dense_tensor_unwrap at /pytorch/aten/src/ATen/Utils.h:72)
我已经在main.cpp中检查了我的模型初始化方法，如果我只进行初始化就可以了。
SimilarityModel simiModel(args, 400000, 300);
simiModel.to(device);
//model forward
torch::Tensor data = ids.index({Slice(i*batch_size, (i+1)*batch_size), Slice()}).to(torch::kInt64).to(device); //take a batch
tie(score, indice) = simiModel.forward(data); //forward and transfer score, indice to cpu for further calculation
这就是我在Similarity.h:中定义相似性模型的方式
class SimilarityModel : public torch::nn::Module {
public:
int64_t topk; // num of top words;
Dictionary dict;
int64_t vocab_size;
int64_t embedding_dim;
torch::nn::Embedding embedding{nullptr};
vector<vector<float> > vec_embed;
SimilarityModel(unordered_map<string, string> args, int64_t vocab_size, int64_t embed_dim);
tuple<torch::Tensor, torch::Tensor> forward(torch::Tensor x);
};
同时，我在Similarity.cpp:中的相似性模型函数中进行了嵌入初始化
SimilarityModel::SimilarityModel(unordered_map<string, string> args, int64_t vocab_size, int64_t embed_dim)
:embedding(vocab_size, embed_dim) { //Embedding initialize
this->topk = stoi(args["topk"]);
vector<vector<float> > pre_embed;
tie(pre_embed, dict) = loadwordvec(args); //load pretrained wordvec from txt file
this->vocab_size = int64_t(dict.size());
this->embedding_dim = int64_t(pre_embed[0].size());
this->vec_embed = pre_embed;
this->dict = dict;
vector<float> temp_embed;
for(const auto& i : pre_embed) //faltten to 1-d
for(const auto& j : i)
temp_embed.push_back(j);
torch::Tensor data = torch::from_blob(temp_embed.data(), {this->vocab_size, this->embedding_dim}, torch::TensorOptions().dtype(torch::kFloat32)).clone(); //vector to tensor
register_module("embedding", embedding);
this->embedding = embedding.from_pretrained(data, torch::nn::EmbeddingFromPretrainedOptions().freeze(true));
}
和相似性.cpp中的正向函数：
tuple<torch::Tensor, torch::Tensor> SimilarityModel::forward(torch::Tensor x) {
auto cuda_available = torch::cuda::is_available(); //copy to gpu
torch::Device device(cuda_available ? torch::kCUDA : torch::kCPU);
torch::Tensor wordvec;
wordvec = this->embedding->forward(x).to(device); //python:embedding(x)
torch::Tensor similarity_score = wordvec.matmul(this->embedding->weight.transpose(0, 1)).to(device);
torch::Tensor score, indice;
tie(score, indice) = similarity_score.topk(this->topk, -1, true, true); //Tensor.topk(int64_t k, int64_t dim, bool largest = true, bool sorted = true)
score = score.to(device);
indice = indice.to(device);
score.slice(1, 1, score.size(1)); //Tensor.slice(int64_t dim, int64_t start, int64_t end, int64_t step)
indice.slice(1, 1, indice.size(1));
return {score.cpu(), indice.cpu()}; //transfer to cpu for further calculation
}
至于forward((中的中间变量也已放入GPU。然而，我完全不知道CPU中剩下哪一个，错误日志也没有多大帮助。我已经尝试了设备类型为cuda的预期对象中的方法，但在调用_th_index_select以执行SimilarityModel().to(device)时，参数#1"self"的设备类型为cpu，但这不起作用。我仍然很难阅读这个错误日志，我想要一些关于如何调试这些问题的说明。
错误日志：
terminate called after throwing an instance of 'c10::Error'
what(): Expected object of device type cuda but got device type cpu for argument #1 'self' in call to _th_index_select (checked_dense_tensor_unwrap at /pytorch/aten/src/ATen/Utils.h:72)
frame #0: c10::Error::Error(c10::SourceLocation, std::string const&) + 0x46 (0x7fb566a27536 in /home/switchsyj/Downloads/libtorch/lib/libc10.so)
frame #1: <unknown function> + 0x101a80b (0x7fb520fa380b in /home/switchsyj/Downloads/libtorch/lib/libtorch_cuda.so)
frame #2: <unknown function> + 0x105009c (0x7fb520fd909c in /home/switchsyj/Downloads/libtorch/lib/libtorch_cuda.so)
frame #3: <unknown function> + 0xf9d76b (0x7fb520f2676b in /home/switchsyj/Downloads/libtorch/lib/libtorch_cuda.so)
frame #4: <unknown function> + 0x10c44e3 (0x7fb558d224e3 in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #5: at::native::embedding(at::Tensor const&, at::Tensor const&, long, bool, bool) + 0x2e2 (0x7fb558870712 in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #6: <unknown function> + 0x114ef9d (0x7fb558dacf9d in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #7: <unknown function> + 0x1187b4d (0x7fb558de5b4d in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #8: <unknown function> + 0x2bfe42f (0x7fb55a85c42f in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #9: <unknown function> + 0x1187b4d (0x7fb558de5b4d in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #10: <unknown function> + 0x32b63a9 (0x7fb55af143a9 in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #11: torch::nn::EmbeddingImpl::forward(at::Tensor const&) + 0x71 (0x7fb55af127b1 in /home/switchsyj/Downloads/libtorch/lib/libtorch_cpu.so)
frame #12: SimilarityModel::forward(at::Tensor) + 0xa9 (0x55c96b8e5793 in ./demo)
frame #13: main + 0xaba (0x55c96b8bfe5c in ./demo)
frame #14: __libc_start_main + 0xe7 (0x7fb51edf5b97 in /lib/x86_64-linux-gnu/libc.so.6)
frame #15: _start + 0x2a (0x55c96b8bd74a in ./demo)
Aborted (core dumped)
根据错误消息，当您运行SimilarityModel::forward():时，以下两个Tensor之一不在GPU中
this->embedding->weightx
假设错误指向argument #1，我认为weight是CPU上的错误。
这是呼叫index.select:
Tensor embedding(const Tensor & weight, const Tensor & indices,
int64_t padding_idx, bool scale_grad_by_freq, bool sparse) {
auto indices_arg = TensorArg(indices, "indices", 1);
checkScalarType("embedding", indices_arg, kLong);
// TODO: use tensor.index() after improving perf
if (indices.dim() == 1) {
return weight.index_select(0, indices);
}
auto size = indices.sizes().vec();
for (auto d : weight.sizes().slice(1)) {
size.push_back(d);
}
return weight.index_select(0, indices.reshape(-1)).view(size);
}
首先，尝试直接将权重移动到GPU。如果它有效，这意味着当您调用TORCH_MODULE(SimilarityModel)并将模型移动到设备时，它也应该有效。请记住，在这种情况下，您必须将名称更改为SimilarityModelImpl(name+Impl(。否则，它将无法正常工作。