How to disable automatic checkpoint loading
Im trying to run a loop over a set of parameters and I wan't to make a new network for each parameter and let it learn a few epochs.
Currently my code looks like this:
def optimize_scale(self, epochs=5, comp_scale=100, scale_list=[1, 100]):
    trainer = pyli.Trainer(gpus=1, max_epochs=epochs)
    
    for scale in scale_list:
        test_model = CustomNN(num_layers=1, scale=scale, lr=1, pad=True, batch_size=1)
        trainer.fit(test_model)
        trainer.test(verbose=True)
        
        del test_model

Everything works fine for the first element of scale_list, the network learns 5 epochs and completes the test. All this can be seen in the console. However for all following elements of scale_list it doesn't work as the old network is not overwritten, but instead an old checkpoint is loaded automatically when trainer.fit(model) is called. In the console this is indicated through:
C:\Users\XXXX\AppData\Roaming\Python\Python39\site-packages\pytorch_lightning\callbacks\model_checkpoint.py:623: UserWarning:
Checkpoint directory D:\XXXX\src\lightning_logs\version_0\checkpoints exists and is not empty.
rank_zero_warn(f&quot;Checkpoint directory {dirpath} exists and is not empty.&quot;)
train_size = 8   val_size = 1    test_size = 1
Restoring states from the checkpoint path at D:\XXXX\src\lightning_logs\version_0\checkpoints\epoch=4-step=39.ckpt
LOCAL_RANK: 0 - CUDA_VISIBLE_DEVICES: [0]
Loaded model weights from checkpoint at D:\XXXX\src\lightning_logs\version_0\checkpoints\epoch=4-step=39.ckpt

The consequence is that the second test outputs the same result, as the the checkpoint from the old network was loaded which already finished all 5 epochs. I though that adding the del test_model might help in dropping the model completely, but that did not work.
On my search I found a few Issues closely related, for example: https://github.com/PyTorchLightning/pytorch-lightning/issues/368. However I did not manage to fix my problem. I assume it has something to with the fact that the new network which should overwrite the old one has the same name/version and therefore looks for the same checkpoints.
If anyone has an idea or knows how to circumvent this I would be very grateful.

I think, in your settings, you want to disable automatic checkpointing:
trainer = pyli.Trainer(gpus=1, max_epochs=epochs,enable_checkpointing=False)

You may need to explicitly save a checkpoint (with a different name) for each training session you are running.
You can manually save a checkpoint via:
trainer.save_checkpoint(f'checkpoint_for_scale_{scale}.pth')

