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# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved | |
# Modified by Jialian Wu from https://github.com/facebookresearch/Detic/blob/main/detic/custom_solver.py | |
import itertools | |
from typing import Any, Callable, Dict, Iterable, List, Set, Type, Union | |
import torch | |
from detectron2.config import CfgNode | |
from detectron2.solver.build import maybe_add_gradient_clipping | |
def build_custom_optimizer(cfg: CfgNode, model: torch.nn.Module) -> torch.optim.Optimizer: | |
params: List[Dict[str, Any]] = [] | |
memo: Set[torch.nn.parameter.Parameter] = set() | |
optimizer_type = cfg.SOLVER.OPTIMIZER | |
for key, value in model.named_parameters(recurse=True): | |
if not value.requires_grad: | |
continue | |
# Avoid duplicating parameters | |
if value in memo: | |
continue | |
memo.add(value) | |
lr = cfg.SOLVER.BASE_LR | |
weight_decay = cfg.SOLVER.WEIGHT_DECAY | |
if cfg.SOLVER.VIT_LAYER_DECAY: | |
lr = lr * get_vit_lr_decay_rate(key, cfg.SOLVER.VIT_LAYER_DECAY_RATE, cfg.MODEL.VIT_LAYERS) | |
param = {"params": [value], "lr": lr} | |
if optimizer_type != 'ADAMW': | |
param['weight_decay'] = weight_decay | |
params += [param] | |
def maybe_add_full_model_gradient_clipping(optim): # optim: the optimizer class | |
# detectron2 doesn't have full model gradient clipping now | |
clip_norm_val = cfg.SOLVER.CLIP_GRADIENTS.CLIP_VALUE | |
enable = ( | |
cfg.SOLVER.CLIP_GRADIENTS.ENABLED | |
and cfg.SOLVER.CLIP_GRADIENTS.CLIP_TYPE == "full_model" | |
and clip_norm_val > 0.0 | |
) | |
class FullModelGradientClippingOptimizer(optim): | |
def step(self, closure=None): | |
all_params = itertools.chain(*[x["params"] for x in self.param_groups]) | |
torch.nn.utils.clip_grad_norm_(all_params, clip_norm_val) | |
super().step(closure=closure) | |
return FullModelGradientClippingOptimizer if enable else optim | |
if optimizer_type == 'SGD': | |
optimizer = maybe_add_full_model_gradient_clipping(torch.optim.SGD)( | |
params, cfg.SOLVER.BASE_LR, momentum=cfg.SOLVER.MOMENTUM, | |
nesterov=cfg.SOLVER.NESTEROV | |
) | |
elif optimizer_type == 'ADAMW': | |
optimizer = maybe_add_full_model_gradient_clipping(torch.optim.AdamW)( | |
params, cfg.SOLVER.BASE_LR, | |
weight_decay=cfg.SOLVER.WEIGHT_DECAY | |
) | |
else: | |
raise NotImplementedError(f"no optimizer type {optimizer_type}") | |
if not cfg.SOLVER.CLIP_GRADIENTS.CLIP_TYPE == "full_model": | |
optimizer = maybe_add_gradient_clipping(cfg, optimizer) | |
return optimizer | |
def get_vit_lr_decay_rate(name, lr_decay_rate=1.0, num_layers=12): | |
""" | |
Calculate lr decay rate for different ViT blocks. | |
Args: | |
name (string): parameter name. | |
lr_decay_rate (float): base lr decay rate. | |
num_layers (int): number of ViT blocks. | |
Returns: | |
lr decay rate for the given parameter. | |
""" | |
layer_id = num_layers + 1 | |
if name.startswith("backbone"): | |
if ".pos_embed" in name or ".patch_embed" in name: | |
layer_id = 0 | |
elif ".blocks." in name and ".residual." not in name: | |
layer_id = int(name[name.find(".blocks.") :].split(".")[2]) + 1 | |
return lr_decay_rate ** (num_layers + 1 - layer_id) |