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Source code for mmselfsup.core.optimizer.constructor
# Copyright (c) OpenMMLab. All rights reserved.
import re
import torch.distributed as dist
from mmcv.runner.optimizer.builder import OPTIMIZER_BUILDERS, OPTIMIZERS
from mmcv.utils import build_from_cfg, print_log
[docs]@OPTIMIZER_BUILDERS.register_module(force=True)
class DefaultOptimizerConstructor:
"""Rewrote default constructor for optimizers. By default each parameter
share the same optimizer settings, and we provide an argument
``paramwise_cfg`` to specify parameter-wise settings. It is a dict and may
contain the following fields:
Args:
model (:obj:`nn.Module`): The model with parameters to be optimized.
optimizer_cfg (dict): The config dict of the optimizer.
Positional fields are
- `type`: class name of the optimizer.
Optional fields are
- any arguments of the corresponding optimizer type, e.g.,
lr, weight_decay, momentum, etc.
paramwise_cfg (dict, optional): Parameter-wise options.
Defaults to None.
Example 1:
>>> model = torch.nn.modules.Conv1d(1, 1, 1)
>>> optimizer_cfg = dict(type='SGD', lr=0.01, momentum=0.9,
>>> weight_decay=0.0001)
>>> paramwise_cfg = dict('bias': dict(weight_decay=0., \
lars_exclude=True))
>>> optim_builder = DefaultOptimizerConstructor(
>>> optimizer_cfg, paramwise_cfg)
>>> optimizer = optim_builder(model)
"""
def __init__(self, optimizer_cfg, paramwise_cfg=None):
if not isinstance(optimizer_cfg, dict):
raise TypeError('optimizer_cfg should be a dict',
f'but got {type(optimizer_cfg)}')
self.optimizer_cfg = optimizer_cfg
self.paramwise_cfg = {} if paramwise_cfg is None else paramwise_cfg
def __call__(self, model):
if hasattr(model, 'module'):
model = model.module
optimizer_cfg = self.optimizer_cfg.copy()
paramwise_options = self.paramwise_cfg
# if no paramwise option is specified, just use the global setting
if paramwise_options is None:
optimizer_cfg['params'] = model.parameters()
return build_from_cfg(optimizer_cfg, OPTIMIZERS)
else:
assert isinstance(paramwise_options, dict)
params = []
for name, param in model.named_parameters():
param_group = {'params': [param]}
if not param.requires_grad:
params.append(param_group)
continue
for regexp, options in paramwise_options.items():
if re.search(regexp, name):
for key, value in options.items():
if key.endswith('_mult'): # is a multiplier
key = key[:-5]
assert key in optimizer_cfg, \
f'{key} not in optimizer_cfg'
value = optimizer_cfg[key] * value
param_group[key] = value
if not dist.is_initialized() or \
dist.get_rank() == 0:
print_log(f'paramwise_options -- \
{name}: {key}={value}')
# otherwise use the global settings
params.append(param_group)
optimizer_cfg['params'] = params
return build_from_cfg(optimizer_cfg, OPTIMIZERS)