Error while saving state of optimizer in Pytorch

Hi all,
I am saving state of optimizer and getting this error
“state_dict() missing 1 required positional argument: ‘self’”.

            'epoch': num_epochs,
            'model_state_dict': model.state_dict(),
            'optimizer_state_dict': opt_func.state_dict(),
            'loss': val_loss,
            'accuracy': val_acc 
            }, '')

Any help shall be highly appreciated

Could you post an executable code snippet which would reproduce the issue?
Based on the error it seems as if you’ve overridden the state_dict method and might be missing an argument. However, you’ve also used the torchx category so I’m unsure if that’s specific to torchx or not.

I did some search and came up with some solution and applied it in my code but still I am having some confusions and also getting errors. So, I am posting my changed code over here:

Question : If I am not passing saved optimizer in my fit function then how it is calculating accuracy and loss?
Confusion: When I am passing optimizer3(saved optimizer) in fit function it is throwing error “Adam is not callable”. (For reference please check attached snapshot).Kindly help me understand the cause of this issue and provide the way to resolve it.

Model Training

def evaluate(model, val_loader):
    outputs = [model.validation_step(batch) for batch in val_loader]
    return model.validation_epoch_end(outputs)
#optimizer = torch.optim.Adam(model.parameters(), lr)
def fit(epochs, lr, model, train_loader, val_loader, opt_func=torch.optim.SGD):
#def fit(epochs, lr, model, train_loader, val_loader, optimizer):  
    history = []
    optimizer = opt_func(model.parameters(), lr)
    for epoch in range(epochs):
        # Training Phase 
        train_losses = []
        for batch in train_loader:
            loss = model.training_step(batch)
        # Validation phase
        result = evaluate(model, val_loader)
        result['train_loss'] = torch.stack(train_losses).mean().item()
        model.epoch_end(epoch, result)
    return history, optimizer
num_epochs = 2
opt_func = torch.optim.Adam
lr = 0.001
history, optimizer = fit(num_epochs, lr, model, train_dl, val_dl, opt_func)


Epoch [0], train_loss: 1.7836, val_loss: 1.4373, val_acc: 0.4659
Epoch [1], train_loss: 1.2700, val_loss: 1.1127, val_acc: 0.6018

# Saving the model and optimizer{
            'epoch': num_epochs,
            'model_state_dict': model.state_dict(),
            'optimizer_state_dict': optimizer.state_dict()            
            }, '')

# Load the model and optimizer
model3 = to_device(Cifar10CnnModel(), device) # instantiate model
optimizer3 = torch.optim.Adam(model3.parameters(), lr) # instantiate optimizer
checkpoint = torch.load('')
model3.load_state_dict(checkpoint['model_state_dict']) # Load model
optimizer3.load_state_dict(checkpoint['optimizer_state_dict']) # load optimizer
epoch = checkpoint['epoch']
history, optimizer = fit(4, lr, model3, train_dl, val_dl) # no optimizer


Epoch [0], train_loss: 1.0236, val_loss: 1.0559, val_acc: 0.6151
Epoch [1], train_loss: 1.0089, val_loss: 1.0491, val_acc: 0.6178
Epoch [2], train_loss: 1.0020, val_loss: 1.0447, val_acc: 0.6209
Epoch [3], train_loss: 0.9967, val_loss: 1.0421, val_acc: 0.6193

The optimizer is not calculating the accuracy or loss and is used to update the passed parameter using the already calculated gradients.

I guess you are passing an optimizer object in this case instead of the function:

model = nn.Linear(1, 1)

# works
opt_func = torch.optim.Adam
optimizer = opt_func(model.parameters(), lr=1e-3)

# raises your error
optimizer = optimizer(model.parameters(), lr=1e-3)
> TypeError: 'Adam' object is not callable

Thank you so much for your guidance. I am still getting error while passing saved optimizer.
history, optimizer = fit(4, lr, model3, train_dl, val_dl, optimizer3)
Still same error!

This is expected.
Your current method uses the opt_func argument as a function not an object:

def fit(epochs, lr, model, train_loader, val_loader, opt_func=torch.optim.SGD):
    optimizer = opt_func(model.parameters(), lr) # !!! this is wrong if opt_func is already an optimizer object

so you would have to change the fit method to accept an optimizer instead of the function.

1 Like

Just checking in to confirm this question, @Sumera_Rounaq you tagged torchx. Is there anything torchx specific you were doing or another reason you tagged this category?

Thank you so much. It really helped alot and i figured out what was my mistake.

Actually I want to deploy my model in next step so for this reason i tagged torchx. Anyways, as of this in hand problem it has nothing to do with torchx. For better understanding of my problem i removed that specific part of code. Hope I clarified.