Improved upsampler training (#181)

Sampling is now possible without the first decoder unet

Non-training unets are deleted in the decoder trainer since they are never used and it is harder merge the models is they have keys in this state dict

Fixed a mistake where clip was not re-added after saving

dalle2_pytorch/dalle2_pytorch.py

@@ -75,6 +75,8 @@ def cast_tuple(val, length = None, validate = True):
     return out
 
 def module_device(module):
+    if isinstance(module, nn.Identity):
+        return 'cpu' # It doesn't matter
     return next(module.parameters()).device
 
 def zero_init_(m):
@@ -2326,7 +2328,7 @@ class Decoder(nn.Module):
 
     @property
     def condition_on_text_encodings(self):
-        return any([unet.cond_on_text_encodings for unet in self.unets])
+        return any([unet.cond_on_text_encodings for unet in self.unets if isinstance(unet, Unet)])
 
     def get_unet(self, unet_number):
         assert 0 < unet_number <= self.num_unets
@@ -2646,11 +2648,13 @@ class Decoder(nn.Module):
     @eval_decorator
     def sample(
         self,
+        image = None,
         image_embed = None,
         text = None,
         text_encodings = None,
         batch_size = 1,
         cond_scale = 1.,
+        start_at_unet_number = 1,
         stop_at_unet_number = None,
         distributed = False,
         inpaint_image = None,
@@ -2671,14 +2675,22 @@ class Decoder(nn.Module):
         assert not (exists(inpaint_image) ^ exists(inpaint_mask)), 'inpaint_image and inpaint_mask (boolean mask of [batch, height, width]) must be both given for inpainting'
 
         img = None
+        if start_at_unet_number > 1:
+            # Then we are not generating the first image and one must have been passed in
+            assert exists(image), 'image must be passed in if starting at unet number > 1'
+            assert image.shape[0] == batch_size, 'image must have batch size of {} if starting at unet number > 1'.format(batch_size)
+            prev_unet_output_size = self.image_sizes[start_at_unet_number - 2]
+            img = resize_image_to(image, prev_unet_output_size, nearest = True)
         is_cuda = next(self.parameters()).is_cuda
 
         num_unets = self.num_unets
         cond_scale = cast_tuple(cond_scale, num_unets)
 
         for unet_number, unet, vae, channel, image_size, predict_x_start, learned_variance, noise_scheduler, lowres_cond, sample_timesteps, unet_cond_scale in tqdm(zip(range(1, num_unets + 1), self.unets, self.vaes, self.sample_channels, self.image_sizes, self.predict_x_start, self.learned_variance, self.noise_schedulers, self.lowres_conds, self.sample_timesteps, cond_scale)):
+            if unet_number < start_at_unet_number:
+                continue  # It's the easiest way to do it
 
-            context = self.one_unet_in_gpu(unet = unet) if is_cuda and not distributed else null_context()
+            context = self.one_unet_in_gpu(unet = unet) if is_cuda else null_context()
 
             with context:
                 # prepare low resolution conditioning for upsamplers

dalle2_pytorch/trackers.py

@@ -530,11 +530,14 @@ class Tracker:
                 prior = trainer.ema_diffusion_prior.ema_model if trainer.use_ema else trainer.diffusion_prior
                 prior: DiffusionPrior = trainer.unwrap_model(prior)
                 # Remove CLIP if it is part of the model
+                original_clip = prior.clip
                 prior.clip = None
                 model_state_dict = prior.state_dict()
+                prior.clip = original_clip
             elif isinstance(trainer, DecoderTrainer):
                 decoder: Decoder = trainer.accelerator.unwrap_model(trainer.decoder)
                 # Remove CLIP if it is part of the model
+                original_clip = decoder.clip
                 decoder.clip = None
                 if trainer.use_ema:
                     trainable_unets = decoder.unets
@@ -543,6 +546,7 @@ class Tracker:
                     decoder.unets = trainable_unets  # Swap back
                 else:
                     model_state_dict = decoder.state_dict()
+                decoder.clip = original_clip
             else:
                 raise NotImplementedError('Saving this type of model with EMA mode enabled is not yet implemented. Actually, how did you get here?')
             state_dict = {

dalle2_pytorch/train_configs.py

@@ -306,9 +306,11 @@ class DecoderTrainConfig(BaseModel):
     max_grad_norm: SingularOrIterable(float) = 0.5
     save_every_n_samples: int = 100000
     n_sample_images: int = 6                       # The number of example images to produce when sampling the train and test dataset
+    cond_scale: Union[float, List[float]] = 1.0
     device: str = 'cuda:0'
     epoch_samples: int = None                      # Limits the number of samples per epoch. None means no limit. Required if resample_train is true as otherwise the number of samples per epoch is infinite.
     validation_samples: int = None                 # Same as above but for validation.
+    save_immediately: bool = False
     use_ema: bool = True
     ema_beta: float = 0.999
     amp: bool = False

dalle2_pytorch/trainer.py

@@ -498,23 +498,27 @@ class DecoderTrainer(nn.Module):
         warmup_schedulers = []
 
         for unet, unet_lr, unet_wd, unet_eps, unet_warmup_steps in zip(decoder.unets, lr, wd, eps, warmup_steps):
-            optimizer = get_optimizer(
-                unet.parameters(),
-                lr = unet_lr,
-                wd = unet_wd,
-                eps = unet_eps,
-                group_wd_params = group_wd_params,
-                **kwargs
-            )
+            if isinstance(unet, nn.Identity):
+                optimizers.append(None)
+                schedulers.append(None)
+                warmup_schedulers.append(None)
+            else:
+                optimizer = get_optimizer(
+                    unet.parameters(),
+                    lr = unet_lr,
+                    wd = unet_wd,
+                    eps = unet_eps,
+                    group_wd_params = group_wd_params,
+                    **kwargs
+                )
 
-            optimizers.append(optimizer)
+                optimizers.append(optimizer)
+                scheduler = LambdaLR(optimizer, lr_lambda = lambda step: 1.0)
 
-            scheduler = LambdaLR(optimizer, lr_lambda = lambda step: 1.0)
+                warmup_scheduler = warmup.LinearWarmup(optimizer, warmup_period = unet_warmup_steps) if exists(unet_warmup_steps) else None
+                warmup_schedulers.append(warmup_scheduler)
 
-            warmup_scheduler = warmup.LinearWarmup(optimizer, warmup_period = unet_warmup_steps) if exists(unet_warmup_steps) else None
-            warmup_schedulers.append(warmup_scheduler)
-
-            schedulers.append(scheduler)
+                schedulers.append(scheduler)
 
             if self.use_ema:
                 self.ema_unets.append(EMA(unet, **ema_kwargs))
@@ -590,7 +594,8 @@ class DecoderTrainer(nn.Module):
         for ind in range(0, self.num_unets):
             optimizer_key = f'optim{ind}'
             optimizer = getattr(self, optimizer_key)
-            save_obj = {**save_obj, optimizer_key: self.accelerator.unwrap_model(optimizer).state_dict()}
+            state_dict = optimizer.state_dict() if optimizer is not None else None
+            save_obj = {**save_obj, optimizer_key: state_dict}
 
         if self.use_ema:
             save_obj = {**save_obj, 'ema': self.ema_unets.state_dict()}
@@ -612,8 +617,8 @@ class DecoderTrainer(nn.Module):
             optimizer_key = f'optim{ind}'
             optimizer = getattr(self, optimizer_key)
             warmup_scheduler = self.warmup_schedulers[ind]
-
-            self.accelerator.unwrap_model(optimizer).load_state_dict(loaded_obj[optimizer_key])
+            if optimizer is not None:
+                optimizer.load_state_dict(loaded_obj[optimizer_key])
 
             if exists(warmup_scheduler):
                 warmup_scheduler.last_step = last_step
@@ -714,23 +719,32 @@ class DecoderTrainer(nn.Module):
         *args,
         unet_number = None,
         max_batch_size = None,
+        return_lowres_cond_image=False,
         **kwargs
     ):
         unet_number = self.validate_and_return_unet_number(unet_number)
 
         total_loss = 0.
-
-        
-        using_amp = self.accelerator.mixed_precision != 'no'
-
+        cond_images = []
         for chunk_size_frac, (chunked_args, chunked_kwargs) in split_args_and_kwargs(*args, split_size = max_batch_size, **kwargs):
             with self.accelerator.autocast():
-                loss = self.decoder(*chunked_args, unet_number = unet_number, **chunked_kwargs)
+                loss_obj = self.decoder(*chunked_args, unet_number = unet_number, return_lowres_cond_image=return_lowres_cond_image, **chunked_kwargs)
+                # loss_obj may be a tuple with loss and cond_image
+                if return_lowres_cond_image:
+                    loss, cond_image = loss_obj
+                else:
+                    loss = loss_obj
+                    cond_image = None
                 loss = loss * chunk_size_frac
+                if cond_image is not None:
+                    cond_images.append(cond_image)
 
             total_loss += loss.item()
 
             if self.training:
                 self.accelerator.backward(loss)
 
-        return total_loss
+        if return_lowres_cond_image:
+            return total_loss, torch.stack(cond_images)
+        else:
+            return total_loss