101 lines
3.5 KiB
Python
101 lines
3.5 KiB
Python
from typing import Dict, List, Optional, Tuple
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import torch
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import torch.optim._functional as F
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from torch import Tensor
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__all__: List[str] = []
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# Define a TorchScript compatible Functional Rprop Optimizer
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# where we use these optimizer in a functional way.
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# Instead of using the `param.grad` when updating parameters,
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# we explicitly allow the distributed optimizer pass gradients to
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# the `step` function. In this way, we could separate the gradients
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# and parameters and allow multithreaded trainer to update the
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# parameters without data traces on accumulating to the same .grad.
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# NOTE: This should be only used by distributed optimizer internals
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# and not meant to expose to the user.
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@torch.jit.script
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class _FunctionalRprop:
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def __init__(
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self,
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params: List[Tensor],
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lr: float = 1e-2,
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etas: Tuple[float, float] = (0.5, 1.2),
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step_sizes: Tuple[float, float] = (1e-6, 50),
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foreach: bool = False,
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maximize: bool = False,
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_allow_empty_param_list: bool = False,
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):
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self.defaults = {
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"lr": lr,
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}
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self.etas = etas
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self.step_sizes = step_sizes
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self.foreach = foreach
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self.maximize = maximize
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if len(params) == 0 and not _allow_empty_param_list:
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raise ValueError("optimizer got an empty parameter list")
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# NOTE: we only have one param_group and don't allow user to add additional
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# param group as it's not a common use case.
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self.param_group = {"params": params}
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self.state = torch.jit.annotate(Dict[torch.Tensor, Dict[str, torch.Tensor]], {})
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def step(self, gradients: List[Optional[Tensor]]):
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params = self.param_group["params"]
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params_with_grad = []
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grads = []
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prevs = []
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step_sizes = []
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lr = self.defaults["lr"]
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etaminus, etaplus = self.etas
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step_size_min, step_size_max = self.step_sizes
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if len(params) != len(gradients):
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raise ValueError(
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"the gradients passed in does not equal to the size of the parameters!"
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+ f"Params length: {len(params)}. "
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+ f"Gradients length: {len(gradients)}"
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)
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has_complex = False
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for param, gradient in zip(params, gradients):
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if gradient is not None:
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has_complex |= torch.is_complex(param)
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params_with_grad.append(param)
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grads.append(gradient)
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# Lazy state initialization
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if param not in self.state:
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self.state[param] = {}
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state = self.state[param]
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state["step"] = torch.tensor(0.0)
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state["prev"] = torch.zeros_like(
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param, memory_format=torch.preserve_format
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)
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state["step_size"] = torch.full_like(gradient, lr)
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state = self.state[param]
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prevs.append(state["prev"])
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step_sizes.append(state["step_size"])
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state["step"] += 1
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with torch.no_grad():
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F.rprop(
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params_with_grad,
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grads,
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prevs,
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step_sizes,
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step_size_min=step_size_min,
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step_size_max=step_size_max,
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etaminus=etaminus,
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etaplus=etaplus,
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foreach=self.foreach,
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maximize=self.maximize,
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has_complex=has_complex,
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)
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