113 lines
5.4 KiB
Python
113 lines
5.4 KiB
Python
import math
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import random
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import torch
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from utils.util import opt_get
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def create_batch_size_optimizer(opt_train):
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if 'batch_size_optimizer' in opt_train.keys():
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if opt_train['batch_size_optimizer']['type'] == 'gradient_direction':
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return GradientDirectionOptimizer(opt_train)
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return MegabatchBatchSizeOptimizer(opt_train)
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# Base class for BatchSizeOptimizers.
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class BatchSizeOptimizer:
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def focus(self, optimizer):
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pass
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def should_step(self, it):
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raise NotImplementedError
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def get_statistics(self):
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return {}
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# BatchSizeOptimizer that just steps every megabatch.
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class MegabatchBatchSizeOptimizer(BatchSizeOptimizer):
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def __init__(self, opt_train):
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pass
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def should_step(self, it):
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return True
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# BatchSizeOptimizer that uses the gradient direction of a few parameters to determine when to step.
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# Very similar to what is described in https://aclanthology.org/2020.acl-main.323.pdf
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# Special note: this class will ALWAYS accumulate, at a minimum, 3 batches. Plan accordingly.
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class GradientDirectionOptimizer(BatchSizeOptimizer):
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def __init__(self, opt_train):
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self.opt = opt_train['batch_size_optimizer']
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self.max_full_batches = opt_get(self.opt, ['max_full_batches'], 10)
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self.parameters_to_poll = opt_get(self.opt, ['poll_parameters'], 8)
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self.recalculate_directions_every = opt_get(self.opt, ['recalculate_directions_steps'], 1)
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self.current_model = None
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# Metrics
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self.steps_taken = 0
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self.last_number_iterations = torch.zeros((128,))
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self.last_number_iterations_i = 0
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self.last_number_iterations_filled = False
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def vector_angle(self, v1, v2):
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if torch.all(v1 == 0) or torch.all(v2 == 0):
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return torch.tensor(0, device=v1.device)
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with torch.no_grad():
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v1 = v1.flatten()
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v2 = v2.flatten()
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v1_norm = (v1 ** 2).sum().sqrt()
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v2_norm = (v2 ** 2).sum().sqrt()
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angle = torch.arccos((torch.dot(v1, v2)) / (v1_norm * v2_norm))
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return angle
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def focus(self, model):
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if not hasattr(model, '_gradient_direction_optimizer_finished') or model._gradient_direction_optimizer_finished:
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all_params = list(filter(lambda t: '.weight' in t[0] and t[1].requires_grad, list(model.named_parameters()))) # Extracts weight parameters. Who cares about biases anyways? :)
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num_params = min(len(all_params), self.parameters_to_poll)
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model._gradient_direction_optimizer_params = random.sample(all_params, num_params)
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model._gradient_direction_optimizer_prior_directions = [0 for _ in range(num_params)]
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model._gradient_direction_optimizer_direction_change_magnitudes = [math.pi for _ in range(num_params)]
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model._gradient_direction_optimizer_prior_grads = None
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model._gradient_direction_optimizer_step = 0
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model._gradient_direction_optimizer_finished = False
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self.current_model = model
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def should_step(self, it):
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model = self.current_model
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model._gradient_direction_optimizer_step += 1
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cur_grads = [p.grad.detach().clone() for k, p in model._gradient_direction_optimizer_params]
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if model._gradient_direction_optimizer_prior_grads is not None:
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cur_dir = [self.vector_angle(lgrad, cgrad) for lgrad, cgrad in zip(model._gradient_direction_optimizer_prior_grads, cur_grads)]
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delta_dir = [(cdir - ldir) for cdir, ldir in zip(cur_dir, model._gradient_direction_optimizer_prior_directions)]
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delta_delta_dir = torch.stack([pdd - cdd for pdd, cdd in zip(model._gradient_direction_optimizer_direction_change_magnitudes, delta_dir)]).mean().item()
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model._gradient_direction_optimizer_prior_directions = cur_dir
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model._gradient_direction_optimizer_direction_change_magnitudes = delta_dir
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if delta_delta_dir < 0 or model._gradient_direction_optimizer_step >= self.max_full_batches:
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# <0 means the gradient direction is getting larger. Halt batch accumulation here.
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model._gradient_direction_optimizer_finished = True
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self.record_number_steps(model._gradient_direction_optimizer_step)
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# Fix the gradients. We've accumulated _gradient_direction_optimizer_step steps total, so we need to divide the grads by that.
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for p in model.parameters():
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if p.requires_grad:
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p.grad = p.grad / model._gradient_direction_optimizer_step
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return True
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model._gradient_direction_optimizer_prior_grads = cur_grads
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return False
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def record_number_steps(self, steps):
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self.last_number_iterations[self.last_number_iterations_i] = steps
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if self.last_number_iterations_i == self.last_number_iterations.shape[0]-1:
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self.last_number_iterations_filled = True
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self.last_number_iterations_i = (self.last_number_iterations_i + 1) % self.last_number_iterations.shape[0]
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self.steps_taken += 1
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def get_statistics(self):
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res = {"batch_size_opt_total_steps": self.steps_taken}
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if self.last_number_iterations_filled:
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res["batch_size_opt_avg_iterations_per_step"] = self.last_number_iterations.mean().item()
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else:
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res["batch_size_opt_avg_iterations_per_step"] = self.last_number_iterations[:self.last_number_iterations_i].mean().item()
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return res
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