yolov6 / yolov6 /core /engine.py
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#!/usr/bin/env python3
# -*- coding:utf-8 -*-
import os
import time
from copy import deepcopy
import os.path as osp
from tqdm import tqdm
import numpy as np
import torch
from torch.cuda import amp
from torch.nn.parallel import DistributedDataParallel as DDP
from torch.utils.tensorboard import SummaryWriter
import tools.eval as eval
from yolov6.data.data_load import create_dataloader
from yolov6.models.yolo import build_model
from yolov6.models.loss import ComputeLoss
from yolov6.utils.events import LOGGER, NCOLS, load_yaml, write_tblog
from yolov6.utils.ema import ModelEMA, de_parallel
from yolov6.utils.checkpoint import load_state_dict, save_checkpoint, strip_optimizer
from yolov6.solver.build import build_optimizer, build_lr_scheduler
class Trainer:
def __init__(self, args, cfg, device):
self.args = args
self.cfg = cfg
self.device = device
if args.resume:
self.ckpt = torch.load(args.resume, map_location='cpu')
self.rank = args.rank
self.local_rank = args.local_rank
self.world_size = args.world_size
self.main_process = self.rank in [-1, 0]
self.save_dir = args.save_dir
# get data loader
self.data_dict = load_yaml(args.data_path)
self.num_classes = self.data_dict['nc']
self.train_loader, self.val_loader = self.get_data_loader(args, cfg, self.data_dict)
# get model and optimizer
model = self.get_model(args, cfg, self.num_classes, device)
self.optimizer = self.get_optimizer(args, cfg, model)
self.scheduler, self.lf = self.get_lr_scheduler(args, cfg, self.optimizer)
self.ema = ModelEMA(model) if self.main_process else None
# tensorboard
self.tblogger = SummaryWriter(self.save_dir) if self.main_process else None
self.start_epoch = 0
#resume
if hasattr(self, "ckpt"):
resume_state_dict = self.ckpt['model'].float().state_dict() # checkpoint state_dict as FP32
model.load_state_dict(resume_state_dict, strict=True) # load
self.start_epoch = self.ckpt['epoch'] + 1
self.optimizer.load_state_dict(self.ckpt['optimizer'])
if self.main_process:
self.ema.ema.load_state_dict(self.ckpt['ema'].float().state_dict())
self.ema.updates = self.ckpt['updates']
self.model = self.parallel_model(args, model, device)
self.model.nc, self.model.names = self.data_dict['nc'], self.data_dict['names']
self.max_epoch = args.epochs
self.max_stepnum = len(self.train_loader)
self.batch_size = args.batch_size
self.img_size = args.img_size
# Training Process
def train(self):
try:
self.train_before_loop()
for self.epoch in range(self.start_epoch, self.max_epoch):
self.train_in_loop()
except Exception as _:
LOGGER.error('ERROR in training loop or eval/save model.')
raise
finally:
self.train_after_loop()
# Training loop for each epoch
def train_in_loop(self):
try:
self.prepare_for_steps()
for self.step, self.batch_data in self.pbar:
self.train_in_steps()
self.print_details()
except Exception as _:
LOGGER.error('ERROR in training steps.')
raise
try:
self.eval_and_save()
except Exception as _:
LOGGER.error('ERROR in evaluate and save model.')
raise
# Training loop for batchdata
def train_in_steps(self):
images, targets = self.prepro_data(self.batch_data, self.device)
# forward
with amp.autocast(enabled=self.device != 'cpu'):
preds = self.model(images)
total_loss, loss_items = self.compute_loss(preds, targets)
if self.rank != -1:
total_loss *= self.world_size
# backward
self.scaler.scale(total_loss).backward()
self.loss_items = loss_items
self.update_optimizer()
def eval_and_save(self):
remaining_epochs = self.max_epoch - self.epoch
eval_interval = self.args.eval_interval if remaining_epochs > self.args.heavy_eval_range else 1
is_val_epoch = (not self.args.eval_final_only or (remaining_epochs == 1)) and (self.epoch % eval_interval == 0)
if self.main_process:
self.ema.update_attr(self.model, include=['nc', 'names', 'stride']) # update attributes for ema model
if is_val_epoch:
self.eval_model()
self.ap = self.evaluate_results[0] * 0.1 + self.evaluate_results[1] * 0.9
self.best_ap = max(self.ap, self.best_ap)
# save ckpt
ckpt = {
'model': deepcopy(de_parallel(self.model)).half(),
'ema': deepcopy(self.ema.ema).half(),
'updates': self.ema.updates,
'optimizer': self.optimizer.state_dict(),
'epoch': self.epoch,
}
save_ckpt_dir = osp.join(self.save_dir, 'weights')
save_checkpoint(ckpt, (is_val_epoch) and (self.ap == self.best_ap), save_ckpt_dir, model_name='last_ckpt')
del ckpt
# log for tensorboard
write_tblog(self.tblogger, self.epoch, self.evaluate_results, self.mean_loss)
def eval_model(self):
results = eval.run(self.data_dict,
batch_size=self.batch_size // self.world_size * 2,
img_size=self.img_size,
model=self.ema.ema,
dataloader=self.val_loader,
save_dir=self.save_dir,
task='train')
LOGGER.info(f"Epoch: {self.epoch} | mAP@0.5: {results[0]} | mAP@0.50:0.95: {results[1]}")
self.evaluate_results = results[:2]
def train_before_loop(self):
LOGGER.info('Training start...')
self.start_time = time.time()
self.warmup_stepnum = max(round(self.cfg.solver.warmup_epochs * self.max_stepnum), 1000)
self.scheduler.last_epoch = self.start_epoch - 1
self.last_opt_step = -1
self.scaler = amp.GradScaler(enabled=self.device != 'cpu')
self.best_ap, self.ap = 0.0, 0.0
self.evaluate_results = (0, 0) # AP50, AP50_95
self.compute_loss = ComputeLoss(iou_type=self.cfg.model.head.iou_type)
def prepare_for_steps(self):
if self.epoch > self.start_epoch:
self.scheduler.step()
self.model.train()
if self.rank != -1:
self.train_loader.sampler.set_epoch(self.epoch)
self.mean_loss = torch.zeros(4, device=self.device)
self.optimizer.zero_grad()
LOGGER.info(('\n' + '%10s' * 5) % ('Epoch', 'iou_loss', 'l1_loss', 'obj_loss', 'cls_loss'))
self.pbar = enumerate(self.train_loader)
if self.main_process:
self.pbar = tqdm(self.pbar, total=self.max_stepnum, ncols=NCOLS, bar_format='{l_bar}{bar:10}{r_bar}{bar:-10b}')
# Print loss after each steps
def print_details(self):
if self.main_process:
self.mean_loss = (self.mean_loss * self.step + self.loss_items) / (self.step + 1)
self.pbar.set_description(('%10s' + '%10.4g' * 4) % (f'{self.epoch}/{self.max_epoch - 1}', \
*(self.mean_loss)))
# Empty cache if training finished
def train_after_loop(self):
if self.main_process:
LOGGER.info(f'\nTraining completed in {(time.time() - self.start_time) / 3600:.3f} hours.')
save_ckpt_dir = osp.join(self.save_dir, 'weights')
strip_optimizer(save_ckpt_dir, self.epoch) # strip optimizers for saved pt model
if self.device != 'cpu':
torch.cuda.empty_cache()
def update_optimizer(self):
curr_step = self.step + self.max_stepnum * self.epoch
self.accumulate = max(1, round(64 / self.batch_size))
if curr_step <= self.warmup_stepnum:
self.accumulate = max(1, np.interp(curr_step, [0, self.warmup_stepnum], [1, 64 / self.batch_size]).round())
for k, param in enumerate(self.optimizer.param_groups):
warmup_bias_lr = self.cfg.solver.warmup_bias_lr if k == 2 else 0.0
param['lr'] = np.interp(curr_step, [0, self.warmup_stepnum], [warmup_bias_lr, param['initial_lr'] * self.lf(self.epoch)])
if 'momentum' in param:
param['momentum'] = np.interp(curr_step, [0, self.warmup_stepnum], [self.cfg.solver.warmup_momentum, self.cfg.solver.momentum])
if curr_step - self.last_opt_step >= self.accumulate:
self.scaler.step(self.optimizer)
self.scaler.update()
self.optimizer.zero_grad()
if self.ema:
self.ema.update(self.model)
self.last_opt_step = curr_step
@staticmethod
def get_data_loader(args, cfg, data_dict):
train_path, val_path = data_dict['train'], data_dict['val']
# check data
nc = int(data_dict['nc'])
class_names = data_dict['names']
assert len(class_names) == nc, f'the length of class names does not match the number of classes defined'
grid_size = max(int(max(cfg.model.head.strides)), 32)
# create train dataloader
train_loader = create_dataloader(train_path, args.img_size, args.batch_size // args.world_size, grid_size,
hyp=dict(cfg.data_aug), augment=True, rect=False, rank=args.local_rank,
workers=args.workers, shuffle=True, check_images=args.check_images,
check_labels=args.check_labels, data_dict=data_dict, task='train')[0]
# create val dataloader
val_loader = None
if args.rank in [-1, 0]:
val_loader = create_dataloader(val_path, args.img_size, args.batch_size // args.world_size * 2, grid_size,
hyp=dict(cfg.data_aug), rect=True, rank=-1, pad=0.5,
workers=args.workers, check_images=args.check_images,
check_labels=args.check_labels, data_dict=data_dict, task='val')[0]
return train_loader, val_loader
@staticmethod
def prepro_data(batch_data, device):
images = batch_data[0].to(device, non_blocking=True).float() / 255
targets = batch_data[1].to(device)
return images, targets
def get_model(self, args, cfg, nc, device):
model = build_model(cfg, nc, device)
weights = cfg.model.pretrained
if weights: # finetune if pretrained model is set
LOGGER.info(f'Loading state_dict from {weights} for fine-tuning...')
model = load_state_dict(weights, model, map_location=device)
LOGGER.info('Model: {}'.format(model))
return model
@staticmethod
def parallel_model(args, model, device):
# If DP mode
dp_mode = device.type != 'cpu' and args.rank == -1
if dp_mode and torch.cuda.device_count() > 1:
LOGGER.warning('WARNING: DP not recommended, use DDP instead.\n')
model = torch.nn.DataParallel(model)
# If DDP mode
ddp_mode = device.type != 'cpu' and args.rank != -1
if ddp_mode:
model = DDP(model, device_ids=[args.local_rank], output_device=args.local_rank)
return model
def get_optimizer(self, args, cfg, model):
accumulate = max(1, round(64 / args.batch_size))
cfg.solver.weight_decay *= args.batch_size * accumulate / 64
optimizer = build_optimizer(cfg, model)
return optimizer
@staticmethod
def get_lr_scheduler(args, cfg, optimizer):
epochs = args.epochs
lr_scheduler, lf = build_lr_scheduler(cfg, optimizer, epochs)
return lr_scheduler, lf