detectron2_validation_loss_calculator.py

def calculate_validation_loss(validation_dataset_loader, model, storage):
    data = next(validation_dataset_loader)
    with torch.no_grad():
        loss_dict = model(data)

        losses = sum(loss_dict.values())
        assert torch.isfinite(losses).all(), loss_dict

        loss_dict_reduced = {"val_" + k: v.item() for k, v in
                             comm.reduce_dict(loss_dict).items()}
        losses_reduced = sum(loss for loss in loss_dict_reduced.values())
        if comm.is_main_process():
            storage.put_scalars(total_val_loss=losses_reduced,
                                **loss_dict_reduced)