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neural-networkpytorchtorch

net.load_state_dict(torch.load('rnn_x_epoch.net')) not working on cpu


I am using pytorch to train a Neural Network. When I train and test on GPU, it works fine. But When I try to load the model parameters on CPU using:

net.load_state_dict(torch.load('rnn_x_epoch.net'))

I get the following error:

RuntimeError: cuda runtime error (35) : CUDA driver version is insufficient for CUDA runtime version at torch/csrc/cuda/Module.cpp:51

I have searched for the error, it's mainly because of CUDA driver dependency, but since I'm running on CPU when I get this error,it must be something else, or may be I missed something. Since it's working fine using GPU, I could just run it on GPU but I'm trying to train the network on GPU, store the parameters and then load it on CPU mode for predictions. I am just looking for a way to load the parameters while on CPU mode.

I tried this as well to load the parameters:

check = torch.load('rnn_x_epoch.net')

It did not work.

I tried to save the model parameters in two ways, to see if any of these would work, but didn't: 1)

checkpoint = {'n_hidden': net.n_hidden,
          'n_layers': net.n_layers,
          'state_dict': net.state_dict(),
          'tokens': net.chars}

with open('rnn_x_epoch.net', 'wb') as f:
    torch.save(checkpoint, f)

2)

torch.save(model.state_dict(), 'rnn_x_epoch.net')

TraceBack:

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-9-e61f28013b35> in <module>()
----> 1 net.load_state_dict(torch.load('rnn_x_epoch.net'))

/opt/conda/lib/python3.6/site-packages/torch/serialization.py in load(f, map_location, pickle_module)
    301         f = open(f, 'rb')
    302     try:
--> 303         return _load(f, map_location, pickle_module)
    304     finally:
    305         if new_fd:

/opt/conda/lib/python3.6/site-packages/torch/serialization.py in _load(f, map_location, pickle_module)
    467     unpickler = pickle_module.Unpickler(f)
    468     unpickler.persistent_load = persistent_load
--> 469     result = unpickler.load()
    470 
    471     deserialized_storage_keys = pickle_module.load(f)

/opt/conda/lib/python3.6/site-packages/torch/serialization.py in persistent_load(saved_id)
    435             if root_key not in deserialized_objects:
    436                 deserialized_objects[root_key] = restore_location(
--> 437                     data_type(size), location)
    438             storage = deserialized_objects[root_key]
    439             if view_metadata is not None:

/opt/conda/lib/python3.6/site-packages/torch/serialization.py in default_restore_location(storage, location)
     86 def default_restore_location(storage, location):
     87     for _, _, fn in _package_registry:
---> 88         result = fn(storage, location)
     89         if result is not None:
     90             return result

/opt/conda/lib/python3.6/site-packages/torch/serialization.py in _cuda_deserialize(obj, location)
     68     if location.startswith('cuda'):
     69         device = max(int(location[5:]), 0)
---> 70         return obj.cuda(device)
     71 
     72 

/opt/conda/lib/python3.6/site-packages/torch/_utils.py in _cuda(self, device, non_blocking, **kwargs)
     66         if device is None:
     67             device = -1
---> 68     with torch.cuda.device(device):
     69         if self.is_sparse:
     70             new_type = getattr(torch.cuda.sparse, 
self.__class__.__name__)

/opt/conda/lib/python3.6/site-packages/torch/cuda/__init__.py in __enter__(self)
    223         if self.idx is -1:
    224             return
--> 225         self.prev_idx = torch._C._cuda_getDevice()
    226         if self.prev_idx != self.idx:
    227             torch._C._cuda_setDevice(self.idx)

RuntimeError: cuda runtime error (35) : CUDA driver version is insufficient for CUDA runtime version at torch/csrc/cuda/Module.cpp:51

Also may be the save/load operations in Pytorch are only for GPU mode, but I am not really convinced by that.


Solution

  • From the PyTorch documentation:

    When you call torch.load() on a file which contains GPU tensors, those tensors will be loaded to GPU by default.

    To load the model on CPU which was saved on GPU, you need to pass map_location argument as cpu in load function as follows:

    # Load all tensors onto the CPU
    net.load_state_dict(torch.load('rnn_x_epoch.net', map_location=torch.device('cpu')))
    

    In doing so, the storages underlying the tensors are dynamically remapped to the CPU device using the map_location argument. You can read more on the official PyTorch tutorials.

    This can also be done as follows:

    # Load all tensors onto the CPU, using a function
    net.load_state_dict(torch.load('rnn_x_epoch.net', map_location=lambda storage, loc: storage))