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2026-07-13 12:40:42 +08:00

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# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations
import warnings
from typing import TYPE_CHECKING
import paddle
from paddle import _C_ops, pir
from paddle.framework import in_dynamic_or_pir_mode
from paddle.regularizer import L2Decay
from ..base import core, framework
from .optimizer import Optimizer
if TYPE_CHECKING:
from collections.abc import Sequence
from typing_extensions import NotRequired
from paddle import Tensor
from paddle.nn.clip import GradientClipBase
from paddle.regularizer import WeightDecayRegularizer
from .lr import LRScheduler
from .optimizer import _ParameterConfig
class _MomentumParameterConfig(_ParameterConfig):
momentum: NotRequired[float]
use_nesterov: NotRequired[bool]
rescale_grad: NotRequired[float]
regularization_method: NotRequired[str]
regularization_coeff: NotRequired[float]
__all__ = []
class Momentum(Optimizer):
r"""
Simple Momentum optimizer with velocity state
This optimizer has a flag for Nestrov Momentum.
The update equations are as follows:
.. math::
& velocity = mu * velocity + gradient
& if (use\_nesterov):
&\quad param = param - (gradient + mu * velocity) * learning\_rate
& else:
&\quad param = param - learning\_rate * velocity
Parameters:
learning_rate (float|Tensor|LRScheduler, optional): The learning rate used to update ``Parameter``.
It can be a float value, a ``Tensor`` with a float type or a LRScheduler. The default value is 0.001.
momentum (float): Momentum factor. The default value is 0.9.
parameters (list|tuple|None, optional): List|Tuple of ``Tensor`` to update to minimize ``loss``. \
This parameter is required in dygraph mode. And you can specify different options for \
different parameter groups such as the learning rate, weight decay, etc, \
then the parameters are list of dict. Note that the learning_rate in parameter groups \
represents the scale of base learning_rate. \
The default value is None in static graph mode, at this time all parameters will be updated.
use_nesterov(bool, optional): Enables Nesterov momentum. The default value is False.
weight_decay (int|float|WeightDecayRegularizer|None, optional): The strategy of regularization. \
It can be a int or float value as coeff of L2 regularization or \
:ref:`api_paddle_regularizer_L1Decay`, :ref:`api_paddle_regularizer_L2Decay`.
If a parameter has set regularizer using :ref:`api_paddle_ParamAttr` already, \
the regularization setting here in optimizer will be ignored for this parameter. \
Otherwise, the regularization setting here in optimizer will take effect. \
Default None, meaning there is no regularization.
grad_clip (GradientClipBase|None, optional): Gradient clipping strategy, it's an instance of
some derived class of ``GradientClipBase`` . There are three clipping strategies
( :ref:`api_paddle_nn_ClipGradByGlobalNorm` , :ref:`api_paddle_nn_ClipGradByNorm` ,
:ref:`api_paddle_nn_ClipGradByValue` ). Default None, meaning there is no gradient clipping.
multi_precision (bool, optional): Whether to use multi-precision during weight updating. Default is false.
rescale_grad (float, optional): Multiply the gradient with `rescale_grad` before updating. \
Often choose to be ``1.0/batch_size``.
use_multi_tensor (bool, optional): Whether to use multi-tensor strategy to update all parameters at once . Default is false.
name (str|None, optional): The default value is None. Normally there is no need for user
to set this property. For more information, please refer to
:ref:`api_guide_Name` .
Examples:
.. code-block:: pycon
>>> import paddle
>>> inp = paddle.uniform([10, 10], dtype="float32", min=-0.1, max=0.1)
>>> linear = paddle.nn.Linear(10, 10)
>>> inp = paddle.to_tensor(inp)
>>> out = linear(inp)
>>> loss = paddle.mean(out)
>>> momentum = paddle.optimizer.Momentum(
... learning_rate=0.1,
... parameters=linear.parameters(),
... weight_decay=0.01
... )
>>> back = out.backward()
>>> momentum.step()
>>> momentum.clear_grad()
>>> # Note that the learning_rate of linear_2 is 0.01.
>>> linear_1 = paddle.nn.Linear(10, 10)
>>> linear_2 = paddle.nn.Linear(10, 10)
>>> inp = paddle.uniform(shape=[10, 10], min=-0.1, max=0.1)
>>> out = linear_1(inp)
>>> out = linear_2(out)
>>> loss = paddle.mean(out)
>>> momentum = paddle.optimizer.Momentum(
... learning_rate=0.1,
... parameters=[{ # type: ignore
... 'params': linear_1.parameters()
... }, {
... 'params': linear_2.parameters(),
... 'weight_decay': 0.001,
... 'learning_rate': 0.1
... }],
... weight_decay=0.01,
... momentum=0.9
... )
>>> out.backward()
>>> momentum.step()
>>> momentum.clear_grad()
"""
_velocity_acc_str = "velocity"
def __init__(
self,
learning_rate: float | Tensor | LRScheduler = 0.001,
momentum: float = 0.9,
parameters: (
Sequence[Tensor] | Sequence[_MomentumParameterConfig] | None
) = None,
use_nesterov: bool = False,
weight_decay: float | WeightDecayRegularizer | None = None,
grad_clip: GradientClipBase | None = None,
multi_precision: bool = False,
rescale_grad: float = 1.0,
use_multi_tensor: bool = False,
name: str | None = None,
) -> None:
if learning_rate is None:
raise ValueError("learning_rate is not set")
if momentum is None:
raise ValueError("momentum is not set")
if isinstance(weight_decay, int):
weight_decay = float(weight_decay)
predicate = lambda regular: isinstance(regular, (L2Decay, float))
if isinstance(parameters, list):
if isinstance(parameters[0], dict):
for param_group in parameters:
decay = (
param_group['weight_decay']
if 'weight_decay' in param_group
else weight_decay
)
reg_method, reg_coeff = self._update_regularization(decay)
param_group['regularization_method'] = reg_method
param_group['regularization_coeff'] = reg_coeff
py_regular = None if predicate(decay) else decay
param_group['weight_decay'] = py_regular
py_regular = None if predicate(weight_decay) else weight_decay
super().__init__(
learning_rate=learning_rate,
parameters=parameters,
weight_decay=py_regular,
grad_clip=grad_clip,
name=name,
)
self.type = "momentum"
self._momentum = momentum
self._use_nesterov = bool(use_nesterov)
(
self._regularization_method,
self._regularization_coeff,
) = self._update_regularization(weight_decay)
self._multi_precision = multi_precision
self._rescale_grad = rescale_grad
self._master_weights = {}
self._default_dict = {
'momentum': momentum,
'use_nesterov': use_nesterov,
'rescale_grad': rescale_grad,
'regularization_method': self._regularization_method,
'regularization_coeff': self._regularization_coeff,
}
self._use_multi_tensor = use_multi_tensor
if self._use_multi_tensor:
self._param_dict = self._create_multi_tensor_dict()
self._velocity_dict = self._create_multi_tensor_dict()
self._master_weight_dict = self._create_multi_tensor_dict()
self._master_weight_dict['FP32_DenseTensor'] = None
self._regularization_method_dict = self._create_multi_tensor_dict()
self._regularization_coeff_dict = self._create_multi_tensor_dict()
def _update_regularization(self, weight_decay):
reg_method = ""
reg_coeff = 0.0
if isinstance(weight_decay, L2Decay):
reg_method = "l2_decay"
reg_coeff = weight_decay._coeff
if isinstance(weight_decay, float):
reg_method = "l2_decay"
reg_coeff = weight_decay
return reg_method, reg_coeff
def _create_accumulators(self, block, parameters):
'''
if framework.in_dynamic_mode():
return
'''
assert isinstance(block, (framework.Block, paddle.pir.Block))
if isinstance(parameters, dict):
parameters = self._update_param_group(parameters)
for p in parameters:
if p.name in self._already_create_accumulator:
continue
if self._multi_precision and self._is_dtype_fp16_or_bf16(p.dtype):
master_p = self._create_master_weight(p)
self._add_accumulator(self._velocity_acc_str, master_p)
self._already_create_accumulator.add(p.name)
continue
if (
self._is_dtype_fp16_or_bf16(p.dtype)
and not self._multi_precision
):
warnings.warn(
"Accumulating with FP16/BF16 in optimizer can lead to poor accuracy or slow convergence."
"Consider using multi_precision=True option of the Momentum optimizer."
)
self._add_accumulator(self._velocity_acc_str, p)
self._already_create_accumulator.add(p.name)
def _create_regularization_of_grad(self, param, grad, regularization=None):
"""Create and add backward regularization Operators
Function helper of append_regularization_ops.
"""
# If ParamAttr is set to L2Decay, we skip doing regularization here. And then we fused
# L2Decay with momentum which can refer to _append_optimize_op below.
if hasattr(param, 'regularizer') and isinstance(
param.regularizer, L2Decay
):
return grad
return super()._create_regularization_of_grad(
param, grad, regularization
)
def _append_optimize_op(self, block, param_and_grad):
if not isinstance(block, (framework.Block, pir.Block)):
raise TypeError("block is not instance of Block.")
if isinstance(param_and_grad, dict):
param_and_grad = self._update_param_group(param_and_grad)
velocity_acc = self._get_accumulator_master(
self._velocity_acc_str, param_and_grad[0]
)
lr = self._create_param_lr(param_and_grad)
# For fusion of momentum and l2decay
param = param_and_grad[0]
regularization_method = self._regularization_method
regularization_coeff = self._regularization_coeff
if hasattr(param, 'regularizer'):
# we skip param's l2decay before, so fuse it with momentum here.
if isinstance(param.regularizer, L2Decay):
regularization_method = "l2_decay"
regularization_coeff = param.regularizer._coeff
# the param's regularization has been done before, we avoid do l2decay in momentum.
elif param.regularizer is not None:
regularization_method = ""
regularization_coeff = 0.0
find_master = self._multi_precision and self._is_dtype_fp16_or_bf16(
param_and_grad[0].dtype
)
master_weight = (
self._master_weights[param_and_grad[0].name]
if find_master
else None
)
if in_dynamic_or_pir_mode():
if isinstance(param_and_grad, dict):
self._update_regularization(param_and_grad['weight_decay'])
return _C_ops.momentum_(
param_and_grad[0],
param_and_grad[1],
velocity_acc,
lr,
master_weight,
self._momentum,
self._use_nesterov,
regularization_method,
regularization_coeff,
find_master,
self._rescale_grad,
)
else:
attrs = {
"mu": self._momentum,
"use_nesterov": self._use_nesterov,
"regularization_method": regularization_method,
"regularization_coeff": regularization_coeff,
"multi_precision": find_master,
"rescale_grad": self._rescale_grad,
}
inputs = {
"Param": [param_and_grad[0]],
"Grad": [param_and_grad[1]],
"Velocity": [velocity_acc],
"LearningRate": [lr],
}
outputs = {
"ParamOut": [param_and_grad[0]],
"VelocityOut": [velocity_acc],
}
if find_master:
inputs["MasterParam"] = master_weight
outputs["MasterParamOut"] = master_weight
# create the momentum optimize op
momentum_op = block.append_op(
type=self.type,
inputs=inputs,
outputs=outputs,
attrs=attrs,
stop_gradient=True,
)
return momentum_op
def _multi_tensor_init(self, target_block, parameters, param_group_idx):
"""
All parameters used for optimizer (such as: parameters, master_weight, velocity_acc for momentum) calculations are grouped into a python list by data type (float16, bf16, float32).
This function will be overridden in the corresponding optimizer file.
Args:
target_block: the block in which the loss tensor is present
parameters: list of parameter tensors for the optimizer
"""
self._create_accumulators(target_block, parameters)
for param in parameters:
velocity_acc = self._get_accumulator_master(
self._velocity_acc_str, param
)
regularization_method = self._regularization_method
regularization_coeff = self._regularization_coeff
if hasattr(param, 'regularizer'):
# we skip param's l2decay before, so fuse it with momentum here.
if isinstance(param.regularizer, L2Decay):
regularization_method = "l2_decay"
regularization_coeff = param.regularizer._coeff
elif param.regularizer is not None:
regularization_method = ""
regularization_coeff = 0.0
if param.dtype == paddle.float32:
self._param_dict['FP32_DenseTensor'][param_group_idx].append(
param
)
self._velocity_dict['FP32_DenseTensor'][param_group_idx].append(
velocity_acc
)
# fp32 no master weight
self._regularization_method_dict['FP32_DenseTensor'][
param_group_idx
].append(regularization_method)
self._regularization_coeff_dict['FP32_DenseTensor'][
param_group_idx
].append(regularization_coeff)
elif self._is_dtype_fp16_or_bf16(param.dtype):
self._param_dict['FP16_DenseTensor'][param_group_idx].append(
param
)
self._velocity_dict['FP16_DenseTensor'][param_group_idx].append(
velocity_acc
)
if self._multi_precision:
self._master_weight_dict['FP16_DenseTensor'][
param_group_idx
].append(self._master_weights[param.name])
else:
self._master_weight_dict['FP16_DenseTensor'][
param_group_idx
] = None
self._regularization_method_dict['FP16_DenseTensor'][
param_group_idx
].append(regularization_method)
self._regularization_coeff_dict['FP16_DenseTensor'][
param_group_idx
].append(regularization_coeff)
else:
raise ValueError(
"Now multi_tensor_momentum only support fp32, fp16 or bf16 parameters and grad is DENSE_TENSOR."
)
def _append_optimize_multi_tensor_op(
self,
target_block,
parameters_and_grads,
param_group_idx,
):
"""
For Multi Tensor, append optimize merged_operator to block.
"""
assert isinstance(target_block, framework.Block)
grad_dict = {'FP32_DenseTensor': [], 'FP16_DenseTensor': []}
lr_dict = {'FP32_DenseTensor': [], 'FP16_DenseTensor': []}
if isinstance(parameters_and_grads, list):
for param_and_grad in parameters_and_grads:
if param_and_grad[1] is None:
continue
if param_and_grad[0].stop_gradient is False:
if (
param_and_grad[0].dtype == paddle.float32
and param_and_grad[1].type
== core.VarDesc.VarType.DENSE_TENSOR
):
grad_dict['FP32_DenseTensor'].append(param_and_grad[1])
lr = self._create_param_lr(param_and_grad)
lr_dict['FP32_DenseTensor'].append(lr)
elif (
self._is_dtype_fp16_or_bf16(param_and_grad[0].dtype)
and param_and_grad[1].type
== core.VarDesc.VarType.DENSE_TENSOR
):
grad_dict['FP16_DenseTensor'].append(param_and_grad[1])
lr = self._create_param_lr(param_and_grad)
lr_dict['FP16_DenseTensor'].append(lr)
else:
for param_and_grad in parameters_and_grads['params']:
if param_and_grad[1] is None:
continue
if param_and_grad[0].stop_gradient is False:
param_grad_dict = {}
param_grad_dict['params'] = param_and_grad
param_grad_dict.update(
{
k: v
for k, v in parameters_and_grads.items()
if k != 'params'
}
)
param_and_grad = self._update_param_group(param_grad_dict)
if (
param_and_grad[0].dtype == paddle.float32
and param_and_grad[1].type
== core.VarDesc.VarType.DENSE_TENSOR
):
grad_dict['FP32_DenseTensor'].append(param_and_grad[1])
lr = self._create_param_lr(param_and_grad)
lr_dict['FP32_DenseTensor'].append(lr)
elif (
self._is_dtype_fp16_or_bf16(param_and_grad[0].dtype)
and param_and_grad[1].type
== core.VarDesc.VarType.DENSE_TENSOR
):
grad_dict['FP16_DenseTensor'].append(param_and_grad[1])
lr = self._create_param_lr(param_and_grad)
lr_dict['FP16_DenseTensor'].append(lr)
multi_tensor_list = ['FP32_DenseTensor', 'FP16_DenseTensor']
for key in multi_tensor_list:
if len(self._param_dict[key][param_group_idx]) > 0:
find_master = (
self._multi_precision and key == 'FP16_DenseTensor'
)
master_weight = self._master_weight_dict[key]
master_weight = (
master_weight[param_group_idx]
if master_weight is not None
else None
)
if in_dynamic_or_pir_mode():
found_inf = self._get_auxiliary_var('found_inf')
if found_inf:
if isinstance(
found_inf, (core.eager.Tensor, paddle.pir.Value)
):
self._set_auxiliary_var('found_inf', True)
else:
if isinstance(
found_inf, (core.eager.Tensor, paddle.pir.Value)
):
self._set_auxiliary_var('found_inf', False)
_, _, _ = _C_ops.merged_momentum_(
self._param_dict[key][param_group_idx],
grad_dict[key],
self._velocity_dict[key][param_group_idx],
lr_dict[key],
master_weight,
self._momentum,
self._use_nesterov,
self._regularization_method_dict[key][
param_group_idx
],
self._regularization_coeff_dict[key][
param_group_idx
],
find_master,
self._rescale_grad,
)
else:
inputs = {
"Param": self._param_dict[key][param_group_idx],
"Grad": grad_dict[key],
"Velocity": self._velocity_dict[key][param_group_idx],
"LearningRate": lr_dict[key],
}
outputs = {
"ParamOut": self._param_dict[key][param_group_idx],
"VelocityOut": self._velocity_dict[key][
param_group_idx
],
}
attrs = {
"mu": self._momentum,
"use_nesterov": self._use_nesterov,
"regularization_method": self._regularization_method_dict[
key
][param_group_idx],
"regularization_coeff": self._regularization_coeff_dict[
key
][param_group_idx],
}
if find_master:
inputs["MasterParam"] = self._master_weight_dict[key][
param_group_idx
]
outputs["MasterParamOut"] = self._master_weight_dict[
key
][param_group_idx]
attrs["multi_precision"] = find_master
target_block.append_op(
type="merged_momentum",
inputs=inputs,
outputs=outputs,
attrs=attrs,
stop_gradient=True,
)
def _update_param_group(self, parameters):
self._momentum = parameters.get(
'momentum', self._default_dict['momentum']
)
self._use_nesterov = parameters.get(
'use_nesterov', self._default_dict['use_nesterov']
)
self._rescale_grad = parameters.get(
'rescale_grad', self._default_dict['rescale_grad']
)
self._regularization_method = parameters.get(
'regularization_method', self._default_dict['regularization_method']
)
self._regularization_coeff = parameters.get(
'regularization_coeff', self._default_dict['regularization_coeff']
)
parameters = parameters.get('params')
return parameters