mirror of
https://github.com/lucidrains/DALLE2-pytorch.git
synced 2025-12-19 09:44:19 +01:00
714 lines
23 KiB
Python
714 lines
23 KiB
Python
import time
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import copy
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from pathlib import Path
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from math import ceil
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from functools import partial, wraps
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from collections.abc import Iterable
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import torch
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from torch import nn
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from torch.cuda.amp import autocast, GradScaler
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from dalle2_pytorch.dalle2_pytorch import Decoder, DiffusionPrior
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from dalle2_pytorch.optimizer import get_optimizer
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from dalle2_pytorch.version import __version__
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from packaging import version
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from accelerate import Accelerator
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import numpy as np
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# helper functions
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def exists(val):
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return val is not None
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def default(val, d):
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if exists(val):
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return val
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return d() if callable(d) else d
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def cast_tuple(val, length = 1):
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return val if isinstance(val, tuple) else ((val,) * length)
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def pick_and_pop(keys, d):
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values = list(map(lambda key: d.pop(key), keys))
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return dict(zip(keys, values))
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def group_dict_by_key(cond, d):
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return_val = [dict(),dict()]
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for key in d.keys():
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match = bool(cond(key))
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ind = int(not match)
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return_val[ind][key] = d[key]
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return (*return_val,)
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def string_begins_with(prefix, str):
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return str.startswith(prefix)
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def group_by_key_prefix(prefix, d):
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return group_dict_by_key(partial(string_begins_with, prefix), d)
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def groupby_prefix_and_trim(prefix, d):
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kwargs_with_prefix, kwargs = group_dict_by_key(partial(string_begins_with, prefix), d)
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kwargs_without_prefix = dict(map(lambda x: (x[0][len(prefix):], x[1]), tuple(kwargs_with_prefix.items())))
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return kwargs_without_prefix, kwargs
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def num_to_groups(num, divisor):
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groups = num // divisor
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remainder = num % divisor
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arr = [divisor] * groups
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if remainder > 0:
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arr.append(remainder)
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return arr
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def clamp(value, min_value = None, max_value = None):
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assert exists(min_value) or exists(max_value)
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if exists(min_value):
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value = max(value, min_value)
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if exists(max_value):
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value = min(value, max_value)
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return value
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# decorators
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def cast_torch_tensor(fn):
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@wraps(fn)
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def inner(model, *args, **kwargs):
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device = kwargs.pop('_device', next(model.parameters()).device)
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cast_device = kwargs.pop('_cast_device', True)
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kwargs_keys = kwargs.keys()
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all_args = (*args, *kwargs.values())
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split_kwargs_index = len(all_args) - len(kwargs_keys)
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all_args = tuple(map(lambda t: torch.from_numpy(t) if exists(t) and isinstance(t, np.ndarray) else t, all_args))
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if cast_device:
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all_args = tuple(map(lambda t: t.to(device) if exists(t) and isinstance(t, torch.Tensor) else t, all_args))
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args, kwargs_values = all_args[:split_kwargs_index], all_args[split_kwargs_index:]
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kwargs = dict(tuple(zip(kwargs_keys, kwargs_values)))
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out = fn(model, *args, **kwargs)
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return out
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return inner
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# gradient accumulation functions
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def split_iterable(it, split_size):
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accum = []
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for ind in range(ceil(len(it) / split_size)):
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start_index = ind * split_size
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accum.append(it[start_index: (start_index + split_size)])
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return accum
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def split(t, split_size = None):
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if not exists(split_size):
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return t
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if isinstance(t, torch.Tensor):
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return t.split(split_size, dim = 0)
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if isinstance(t, Iterable):
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return split_iterable(t, split_size)
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return TypeError
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def find_first(cond, arr):
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for el in arr:
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if cond(el):
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return el
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return None
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def split_args_and_kwargs(*args, split_size = None, **kwargs):
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all_args = (*args, *kwargs.values())
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len_all_args = len(all_args)
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first_tensor = find_first(lambda t: isinstance(t, torch.Tensor), all_args)
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assert exists(first_tensor)
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batch_size = len(first_tensor)
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split_size = default(split_size, batch_size)
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num_chunks = ceil(batch_size / split_size)
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dict_len = len(kwargs)
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dict_keys = kwargs.keys()
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split_kwargs_index = len_all_args - dict_len
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split_all_args = [split(arg, split_size = split_size) if exists(arg) and isinstance(arg, (torch.Tensor, Iterable)) else ((arg,) * num_chunks) for arg in all_args]
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chunk_sizes = tuple(map(len, split_all_args[0]))
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for (chunk_size, *chunked_all_args) in tuple(zip(chunk_sizes, *split_all_args)):
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chunked_args, chunked_kwargs_values = chunked_all_args[:split_kwargs_index], chunked_all_args[split_kwargs_index:]
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chunked_kwargs = dict(tuple(zip(dict_keys, chunked_kwargs_values)))
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chunk_size_frac = chunk_size / batch_size
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yield chunk_size_frac, (chunked_args, chunked_kwargs)
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# exponential moving average wrapper
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class EMA(nn.Module):
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"""
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Implements exponential moving average shadowing for your model.
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Utilizes an inverse decay schedule to manage longer term training runs.
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By adjusting the power, you can control how fast EMA will ramp up to your specified beta.
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@crowsonkb's notes on EMA Warmup:
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If gamma=1 and power=1, implements a simple average. gamma=1, power=2/3 are
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good values for models you plan to train for a million or more steps (reaches decay
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factor 0.999 at 31.6K steps, 0.9999 at 1M steps), gamma=1, power=3/4 for models
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you plan to train for less (reaches decay factor 0.999 at 10K steps, 0.9999 at
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215.4k steps).
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Args:
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inv_gamma (float): Inverse multiplicative factor of EMA warmup. Default: 1.
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power (float): Exponential factor of EMA warmup. Default: 1.
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min_value (float): The minimum EMA decay rate. Default: 0.
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"""
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def __init__(
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self,
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model,
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beta = 0.9999,
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update_after_step = 100,
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update_every = 10,
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inv_gamma = 1.0,
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power = 2/3,
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min_value = 0.0,
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):
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super().__init__()
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self.beta = beta
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self.online_model = model
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self.ema_model = copy.deepcopy(model)
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self.update_every = update_every
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self.update_after_step = update_after_step
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self.inv_gamma = inv_gamma
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self.power = power
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self.min_value = min_value
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self.register_buffer('initted', torch.Tensor([False]))
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self.register_buffer('step', torch.tensor([0]))
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def restore_ema_model_device(self):
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device = self.initted.device
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self.ema_model.to(device)
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def copy_params_from_model_to_ema(self):
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for ma_param, current_param in zip(list(self.ema_model.parameters()), list(self.online_model.parameters())):
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ma_param.data.copy_(current_param.data)
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for ma_buffer, current_buffer in zip(list(self.ema_model.buffers()), list(self.online_model.buffers())):
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ma_buffer.data.copy_(current_buffer.data)
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def get_current_decay(self):
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epoch = clamp(self.step.item() - self.update_after_step - 1, min_value = 0)
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value = 1 - (1 + epoch / self.inv_gamma) ** - self.power
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if epoch <= 0:
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return 0.
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return clamp(value, min_value = self.min_value, max_value = self.beta)
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def update(self):
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step = self.step.item()
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self.step += 1
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if (step % self.update_every) != 0:
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return
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if step <= self.update_after_step:
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self.copy_params_from_model_to_ema()
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return
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if not self.initted.item():
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self.copy_params_from_model_to_ema()
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self.initted.data.copy_(torch.Tensor([True]))
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self.update_moving_average(self.ema_model, self.online_model)
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@torch.no_grad()
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def update_moving_average(self, ma_model, current_model):
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current_decay = self.get_current_decay()
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for current_params, ma_params in zip(list(current_model.parameters()), list(ma_model.parameters())):
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difference = ma_params.data - current_params.data
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difference.mul_(1.0 - current_decay)
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ma_params.sub_(difference)
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for current_buffer, ma_buffer in zip(list(current_model.buffers()), list(ma_model.buffers())):
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difference = ma_buffer - current_buffer
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difference.mul_(1.0 - current_decay)
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ma_buffer.sub_(difference)
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def __call__(self, *args, **kwargs):
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return self.ema_model(*args, **kwargs)
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# diffusion prior trainer
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def prior_sample_in_chunks(fn):
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@wraps(fn)
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def inner(self, *args, max_batch_size = None, **kwargs):
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if not exists(max_batch_size):
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return fn(self, *args, **kwargs)
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outputs = [fn(self, *chunked_args, **chunked_kwargs) for _, (chunked_args, chunked_kwargs) in split_args_and_kwargs(*args, split_size = max_batch_size, **kwargs)]
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return torch.cat(outputs, dim = 0)
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return inner
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class DiffusionPriorTrainer(nn.Module):
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def __init__(
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self,
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diffusion_prior,
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use_ema = True,
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lr = 3e-4,
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wd = 1e-2,
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eps = 1e-6,
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max_grad_norm = None,
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amp = False,
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group_wd_params = True,
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device = None,
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accelerator = None,
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**kwargs
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):
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super().__init__()
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assert isinstance(diffusion_prior, DiffusionPrior)
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assert not exists(accelerator) or isinstance(accelerator, Accelerator)
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assert exists(accelerator) or exists(device), "You must supply some method of obtaining a device."
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ema_kwargs, kwargs = groupby_prefix_and_trim('ema_', kwargs)
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# assign some helpful member vars
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self.accelerator = accelerator
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self.device = accelerator.device if exists(accelerator) else device
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self.text_conditioned = diffusion_prior.condition_on_text_encodings
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# save model
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self.diffusion_prior = diffusion_prior
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# optimizer and mixed precision stuff
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self.amp = amp
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self.scaler = GradScaler(enabled = amp)
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self.optim_kwargs = dict(lr=lr, wd=wd, eps=eps, group_wd_params=group_wd_params)
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self.optimizer = get_optimizer(
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self.diffusion_prior.parameters(),
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**self.optim_kwargs,
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**kwargs
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)
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# distribute the model if using HFA
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if exists(self.accelerator):
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self.diffusion_prior, self.optimizer = self.accelerator.prepare(self.diffusion_prior, self.optimizer)
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# exponential moving average stuff
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self.use_ema = use_ema
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if self.use_ema:
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self.ema_diffusion_prior = EMA(self.unwrap_model(self.diffusion_prior), **ema_kwargs)
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# gradient clipping if needed
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self.max_grad_norm = max_grad_norm
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# track steps internally
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self.register_buffer('step', torch.tensor([0]))
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# accelerator wrappers
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def print(self, msg):
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if exists(self.accelerator):
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self.accelerator.print(msg)
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else:
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print(msg)
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def unwrap_model(self, model):
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if exists(self.accelerator):
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return self.accelerator.unwrap_model(model)
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else:
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return model
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def wait_for_everyone(self):
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if exists(self.accelerator):
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self.accelerator.wait_for_everyone()
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def is_main_process(self):
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if exists(self.accelerator):
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return self.accelerator.is_main_process
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else:
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return True
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def clip_grad_norm_(self, *args):
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if exists(self.accelerator):
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return self.accelerator.clip_grad_norm_(*args)
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else:
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return torch.nn.utils.clip_grad_norm_(*args)
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def backprop(self, x):
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if exists(self.accelerator):
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self.accelerator.backward(x)
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else:
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try:
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x.backward()
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except Exception as e:
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self.print(f"Caught error in backprop call: {e}")
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# utility
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def save(self, path, overwrite = True, **kwargs):
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# ensure we sync gradients before continuing
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self.wait_for_everyone()
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# only save on the main process
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if self.is_main_process():
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self.print(f"Saving checkpoint at step: {self.step.item()}")
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path = Path(path)
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assert not (path.exists() and not overwrite)
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path.parent.mkdir(parents = True, exist_ok = True)
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save_obj = dict(
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scaler = self.scaler.state_dict(),
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optimizer = self.optimizer.state_dict(),
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model = self.unwrap_model(self.diffusion_prior).state_dict(), # unwrap the model from distribution if applicable
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version = version.parse(__version__),
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step = self.step.item(),
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**kwargs
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)
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if self.use_ema:
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save_obj = {
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**save_obj,
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'ema': self.ema_diffusion_prior.state_dict(),
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'ema_model': self.ema_diffusion_prior.ema_model.state_dict() # save the ema model specifically for easy ema-only reload
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}
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torch.save(save_obj, str(path))
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def load(self, path, overwrite_lr = True, strict = True):
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"""
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Load a checkpoint of a diffusion prior trainer.
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Will load the entire trainer, including the optimizer and EMA.
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Params:
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- path (str): a path to the DiffusionPriorTrainer checkpoint file
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- overwrite_lr (bool): wether or not to overwrite the stored LR with the LR specified in the new trainer
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- strict (bool): kwarg for `torch.nn.Module.load_state_dict`, will force an exact checkpoint match
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Returns:
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loaded_obj (dict): The loaded checkpoint dictionary
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"""
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# all processes need to load checkpoint. no restriction here
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path = Path(path)
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assert path.exists()
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loaded_obj = torch.load(str(path), map_location=self.device)
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if version.parse(__version__) != loaded_obj['version']:
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print(f'loading saved diffusion prior at version {loaded_obj["version"]} but current package version is at {__version__}')
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# unwrap the model when loading from checkpoint
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self.unwrap_model(self.diffusion_prior).load_state_dict(loaded_obj['model'], strict = strict)
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self.step.copy_(torch.ones_like(self.step) * loaded_obj['step'])
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self.scaler.load_state_dict(loaded_obj['scaler'])
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self.optimizer.load_state_dict(loaded_obj['optimizer'])
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if overwrite_lr:
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new_lr = self.optim_kwargs["lr"]
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self.print(f"Overriding LR to be {new_lr}")
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for group in self.optimizer.param_groups:
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group["lr"] = new_lr
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if self.use_ema:
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assert 'ema' in loaded_obj
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self.ema_diffusion_prior.load_state_dict(loaded_obj['ema'], strict = strict)
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# below not be necessary, but I had a suspicion that this wasn't being loaded correctly
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self.ema_diffusion_prior.ema_model.load_state_dict(loaded_obj["ema_model"])
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# sync and inform
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self.wait_for_everyone()
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self.print(f"Loaded model")
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return loaded_obj
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# model functionality
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def update(self):
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# only continue with updates until all ranks finish
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self.wait_for_everyone()
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if exists(self.max_grad_norm):
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self.scaler.unscale_(self.optimizer)
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# utilize HFA clipping where applicable
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self.clip_grad_norm_(self.diffusion_prior.parameters(), self.max_grad_norm)
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self.scaler.step(self.optimizer)
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self.scaler.update()
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self.optimizer.zero_grad()
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if self.use_ema:
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self.ema_diffusion_prior.update()
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self.step += 1
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@torch.no_grad()
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@cast_torch_tensor
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@prior_sample_in_chunks
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def p_sample_loop(self, *args, **kwargs):
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model = self.ema_diffusion_prior.ema_model if self.use_ema else self.diffusion_prior
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return model.p_sample_loop(*args, **kwargs)
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@torch.no_grad()
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@cast_torch_tensor
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@prior_sample_in_chunks
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def sample(self, *args, **kwargs):
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model = self.ema_diffusion_prior.ema_model if self.use_ema else self.diffusion_prior
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return model.sample(*args, **kwargs)
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@torch.no_grad()
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def sample_batch_size(self, *args, **kwargs):
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model = self.ema_diffusion_prior.ema_model if self.use_ema else self.diffusion_prior
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return model.sample_batch_size(*args, **kwargs)
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@torch.no_grad()
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@cast_torch_tensor
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@prior_sample_in_chunks
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def embed_text(self, *args, **kwargs):
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return self.unwrap_model(self.diffusion_prior).clip.embed_text(*args, **kwargs)
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@cast_torch_tensor
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def forward(
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self,
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*args,
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max_batch_size = None,
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**kwargs
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):
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total_loss = 0.
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for chunk_size_frac, (chunked_args, chunked_kwargs) in split_args_and_kwargs(*args, split_size = max_batch_size, **kwargs):
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with autocast(enabled = self.amp):
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loss = self.diffusion_prior(*chunked_args, **chunked_kwargs)
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loss = loss * chunk_size_frac
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total_loss += loss.item()
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|
# backprop with accelerate if applicable
|
|
|
|
if self.training:
|
|
self.backprop(self.scaler.scale(loss))
|
|
|
|
return total_loss
|
|
|
|
# decoder trainer
|
|
|
|
def decoder_sample_in_chunks(fn):
|
|
@wraps(fn)
|
|
def inner(self, *args, max_batch_size = None, **kwargs):
|
|
if not exists(max_batch_size):
|
|
return fn(self, *args, **kwargs)
|
|
|
|
if self.decoder.unconditional:
|
|
batch_size = kwargs.get('batch_size')
|
|
batch_sizes = num_to_groups(batch_size, max_batch_size)
|
|
outputs = [fn(self, *args, **{**kwargs, 'batch_size': sub_batch_size}) for sub_batch_size in batch_sizes]
|
|
else:
|
|
outputs = [fn(self, *chunked_args, **chunked_kwargs) for _, (chunked_args, chunked_kwargs) in split_args_and_kwargs(*args, split_size = max_batch_size, **kwargs)]
|
|
|
|
return torch.cat(outputs, dim = 0)
|
|
return inner
|
|
|
|
class DecoderTrainer(nn.Module):
|
|
def __init__(
|
|
self,
|
|
decoder,
|
|
accelerator = None,
|
|
use_ema = True,
|
|
lr = 1e-4,
|
|
wd = 1e-2,
|
|
eps = 1e-8,
|
|
max_grad_norm = 0.5,
|
|
amp = False,
|
|
group_wd_params = True,
|
|
**kwargs
|
|
):
|
|
super().__init__()
|
|
assert isinstance(decoder, Decoder)
|
|
ema_kwargs, kwargs = groupby_prefix_and_trim('ema_', kwargs)
|
|
|
|
self.accelerator = default(accelerator, Accelerator)
|
|
|
|
self.num_unets = len(decoder.unets)
|
|
|
|
self.use_ema = use_ema
|
|
self.ema_unets = nn.ModuleList([])
|
|
|
|
self.amp = amp
|
|
|
|
# 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))
|
|
|
|
optimizers = []
|
|
|
|
for unet, unet_lr, unet_wd, unet_eps in zip(decoder.unets, lr, wd, eps):
|
|
optimizer = get_optimizer(
|
|
unet.parameters(),
|
|
lr = unet_lr,
|
|
wd = unet_wd,
|
|
eps = unet_eps,
|
|
group_wd_params = group_wd_params,
|
|
**kwargs
|
|
)
|
|
|
|
optimizers.append(optimizer)
|
|
|
|
if self.use_ema:
|
|
self.ema_unets.append(EMA(unet, **ema_kwargs))
|
|
|
|
# gradient clipping if needed
|
|
|
|
self.max_grad_norm = max_grad_norm
|
|
|
|
self.register_buffer('step', torch.tensor([0.]))
|
|
|
|
decoder, *optimizers = list(self.accelerator.prepare(decoder, *optimizers))
|
|
|
|
self.decoder = decoder
|
|
|
|
for opt_ind, optimizer in zip(range(len(optimizers)), optimizers):
|
|
setattr(self, f'optim{opt_ind}', optimizer)
|
|
|
|
def save(self, path, overwrite = True, **kwargs):
|
|
path = Path(path)
|
|
assert not (path.exists() and not overwrite)
|
|
path.parent.mkdir(parents = True, exist_ok = True)
|
|
|
|
save_obj = dict(
|
|
model = self.accelerator.unwrap_model(self.decoder).state_dict(),
|
|
version = __version__,
|
|
step = self.step.item(),
|
|
**kwargs
|
|
)
|
|
|
|
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()}
|
|
|
|
if self.use_ema:
|
|
save_obj = {**save_obj, 'ema': self.ema_unets.state_dict()}
|
|
|
|
self.accelerator.save(save_obj, str(path))
|
|
|
|
def load(self, path, only_model = False, strict = True):
|
|
path = Path(path)
|
|
assert path.exists()
|
|
|
|
loaded_obj = torch.load(str(path), map_location = 'cpu')
|
|
|
|
if version.parse(__version__) != version.parse(loaded_obj['version']):
|
|
self.accelerator.print(f'loading saved decoder at version {loaded_obj["version"]}, but current package version is {__version__}')
|
|
|
|
self.accelerator.unwrap_model(self.decoder).load_state_dict(loaded_obj['model'], strict = strict)
|
|
self.step.copy_(torch.ones_like(self.step) * loaded_obj['step'])
|
|
|
|
if only_model:
|
|
return loaded_obj
|
|
|
|
for ind in range(0, self.num_unets):
|
|
optimizer_key = f'optim{ind}'
|
|
optimizer = getattr(self, optimizer_key)
|
|
|
|
self.accelerator.unwrap_model(optimizer).load_state_dict(loaded_obj[optimizer_key])
|
|
|
|
if self.use_ema:
|
|
assert 'ema' in loaded_obj
|
|
self.ema_unets.load_state_dict(loaded_obj['ema'], strict = strict)
|
|
|
|
return loaded_obj
|
|
|
|
@property
|
|
def unets(self):
|
|
return nn.ModuleList([ema.ema_model for ema in self.ema_unets])
|
|
|
|
def update(self, unet_number = None):
|
|
if self.num_unets == 1:
|
|
unet_number = default(unet_number, 1)
|
|
|
|
assert exists(unet_number) and 1 <= unet_number <= self.num_unets
|
|
index = unet_number - 1
|
|
|
|
optimizer = getattr(self, f'optim{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()
|
|
|
|
if self.use_ema:
|
|
ema_unet = self.ema_unets[index]
|
|
ema_unet.update()
|
|
|
|
self.step += 1
|
|
|
|
@torch.no_grad()
|
|
@cast_torch_tensor
|
|
@decoder_sample_in_chunks
|
|
def sample(self, *args, **kwargs):
|
|
distributed = self.accelerator.num_processes > 1
|
|
base_decoder = self.accelerator.unwrap_model(self.decoder)
|
|
if kwargs.pop('use_non_ema', False) or not self.use_ema:
|
|
return base_decoder.sample(*args, **kwargs, distributed = distributed)
|
|
|
|
trainable_unets = self.accelerator.unwrap_model(self.decoder).unets
|
|
base_decoder.unets = self.unets # swap in exponential moving averaged unets for sampling
|
|
|
|
output = base_decoder.sample(*args, **kwargs, distributed = distributed)
|
|
|
|
base_decoder.unets = trainable_unets # restore original training unets
|
|
|
|
# cast the ema_model unets back to original device
|
|
for ema in self.ema_unets:
|
|
ema.restore_ema_model_device()
|
|
|
|
return output
|
|
|
|
@cast_torch_tensor
|
|
def forward(
|
|
self,
|
|
*args,
|
|
unet_number = None,
|
|
max_batch_size = None,
|
|
**kwargs
|
|
):
|
|
if self.num_unets == 1:
|
|
unet_number = default(unet_number, 1)
|
|
|
|
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
|
|
|
|
total_loss += loss.item()
|
|
|
|
if self.training:
|
|
self.accelerator.backward(loss)
|
|
|
|
return total_loss
|