set ability to do warmup steps for each unet during training

dalle2_pytorch/train_configs.py

@@ -293,6 +293,7 @@ class DecoderTrainConfig(BaseModel):
     epochs: int = 20
     lr: SingularOrIterable(float) = 1e-4
     wd: SingularOrIterable(float) = 0.01
+    warmup_steps: Optional[SingularOrIterable(int)] = None
     find_unused_parameters: bool = True
     max_grad_norm: SingularOrIterable(float) = 0.5
     save_every_n_samples: int = 100000

dalle2_pytorch/trainer.py

@@ -3,11 +3,13 @@ import copy
 from pathlib import Path
 from math import ceil
 from functools import partial, wraps
+from contextlib import nullcontext
 from collections.abc import Iterable
 
 import torch
 import torch.nn.functional as F
 from torch import nn
+from torch.optim.lr_scheduler import LambdaLR
 from torch.cuda.amp import autocast, GradScaler
 
 from dalle2_pytorch.dalle2_pytorch import Decoder, DiffusionPrior
@@ -15,6 +17,8 @@ from dalle2_pytorch.optimizer import get_optimizer
 from dalle2_pytorch.version import __version__
 from packaging import version
 
+import pytorch_warmup as warmup
+
 from ema_pytorch import EMA
 
 from accelerate import Accelerator
@@ -163,6 +167,7 @@ class DiffusionPriorTrainer(nn.Module):
         group_wd_params = True,
         device = None,
         accelerator = None,
+        verbose = True,
         **kwargs
     ):
         super().__init__()
@@ -209,6 +214,10 @@ class DiffusionPriorTrainer(nn.Module):
 
         self.max_grad_norm = max_grad_norm
 
+        # verbosity
+
+        self.verbose = verbose
+
         # track steps internally
 
         self.register_buffer('step', torch.tensor([0]))
@@ -216,6 +225,9 @@ class DiffusionPriorTrainer(nn.Module):
     # accelerator wrappers
 
     def print(self, msg):
+        if not self.verbose:
+            return
+
         if exists(self.accelerator):
             self.accelerator.print(msg)
         else:
@@ -429,6 +441,7 @@ class DecoderTrainer(nn.Module):
         lr = 1e-4,
         wd = 1e-2,
         eps = 1e-8,
+        warmup_steps = None,
         max_grad_norm = 0.5,
         amp = False,
         group_wd_params = True,
@@ -450,13 +463,15 @@ class DecoderTrainer(nn.Module):
         # be able to finely customize learning rate, weight decay
         # per unet
 
-        lr, wd, eps = map(partial(cast_tuple, length = self.num_unets), (lr, wd, eps))
+        lr, wd, eps, warmup_steps = map(partial(cast_tuple, length = self.num_unets), (lr, wd, eps, warmup_steps))
 
         assert all([unet_lr < 1e-3 for unet_lr in lr]), 'your learning rate is too high, recommend sticking with 1e-4, at most 5e-4'
 
         optimizers = []
+        schedulers = []
+        warmup_schedulers = []
 
-        for unet, unet_lr, unet_wd, unet_eps in zip(decoder.unets, lr, wd, eps):
+        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,
@@ -468,6 +483,13 @@ class DecoderTrainer(nn.Module):
 
             optimizers.append(optimizer)
 
+            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)
+
+            schedulers.append(scheduler)
+
             if self.use_ema:
                 self.ema_unets.append(EMA(unet, **ema_kwargs))
 
@@ -478,12 +500,24 @@ class DecoderTrainer(nn.Module):
         self.register_buffer('steps', torch.tensor([0] * self.num_unets))
 
         decoder, *optimizers = list(self.accelerator.prepare(decoder, *optimizers))
+        schedulers = list(self.accelerator.prepare(*schedulers))
 
         self.decoder = decoder
 
+        # store optimizers
+
         for opt_ind, optimizer in zip(range(len(optimizers)), optimizers):
             setattr(self, f'optim{opt_ind}', optimizer)
 
+        # store schedulers
+
+        for sched_ind, scheduler in zip(range(len(schedulers)), schedulers):
+            setattr(self, f'sched{sched_ind}', scheduler)
+
+        # store warmup schedulers
+
+        self.warmup_schedulers = warmup_schedulers
+
     def save(self, path, overwrite = True, **kwargs):
         path = Path(path)
         assert not (path.exists() and not overwrite)
@@ -516,12 +550,17 @@ class DecoderTrainer(nn.Module):
         if only_model:
             return loaded_obj
 
-        for ind in range(0, self.num_unets):
+        for ind, last_step in zip(range(0, self.num_unets), self.steps.cpu().unbind()):
+
             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 exists(warmup_scheduler):
+                warmup_scheduler.last_step = last_step
+
         if self.use_ema:
             assert 'ema' in loaded_obj
             self.ema_unets.load_state_dict(loaded_obj['ema'], strict = strict)
@@ -554,12 +593,20 @@ class DecoderTrainer(nn.Module):
         index = unet_number - 1
 
         optimizer = getattr(self, f'optim{index}')
+        scheduler = getattr(self, f'sched{index}')
 
         if exists(self.max_grad_norm):
             self.accelerator.clip_grad_norm_(self.decoder.parameters(), self.max_grad_norm)  # Automatically unscales gradients
+
         optimizer.step()
         optimizer.zero_grad()
 
+        warmup_scheduler = self.warmup_schedulers[index]
+        scheduler_context = warmup_scheduler.dampening if exists(warmup_scheduler) else nullcontext
+
+        with scheduler_context():
+            scheduler.step()
+
         if self.use_ema:
             ema_unet = self.ema_unets[index]
             ema_unet.update()
@@ -614,7 +661,6 @@ class DecoderTrainer(nn.Module):
         total_loss = 0.
 
         for chunk_size_frac, (chunked_args, chunked_kwargs) in split_args_and_kwargs(*args, split_size = max_batch_size, **kwargs):
-            # with autocast(enabled = self.amp):
             with self.accelerator.autocast():
                 loss = self.decoder(*chunked_args, unet_number = unet_number, **chunked_kwargs)
                 loss = loss * chunk_size_frac

dalle2_pytorch/version.py

@@ -1 +1 @@
-__version__ = '0.16.3'
+__version__ = '0.16.5'

setup.py

@@ -37,6 +37,7 @@ setup(
     'packaging',
     'pillow',
     'pydantic',
+    'pytorch-warmup',
     'resize-right>=0.0.2',
     'rotary-embedding-torch',
     'torch>=1.10',