engine_pretrain.py

# Copyright (c) SenseTime.
# All rights reserved.

# This source code is licensed under the license found in the
# LICENSE file in the root directory of this source tree.
# --------------------------------------------------------
# References:
# DeiT: https://github.com/facebookresearch/deit
# BEiT: https://github.com/microsoft/unilm/tree/master/beit
# MAE:  https://github.com/facebookresearch/mae
# --------------------------------------------------------

import sys
import math
import torch
from typing import Iterable

import utils_pretrain.misc as misc
import utils_pretrain.lr_sched as lr_sched

from torchvision.transforms import Resize


def train_one_epoch(model: torch.nn.Module,
                    data_loader: Iterable, optimizer: torch.optim.Optimizer,
                    device: torch.device, epoch: int, loss_scaler,
                    log_writer=None,
                    args=None):
    model.train(True)
    metric_logger = misc.MetricLogger(delimiter="  ")
    metric_logger.add_meter('lr', misc.SmoothedValue(window_size=1, fmt='{value:.6f}'))
    header = 'Epoch: [{}]'.format(epoch)
    print_freq = 2

    accum_iter = args.accum_iter

    optimizer.zero_grad()

    # if log_writer is not None:
    #     print('log_dir: {}'.format(log_writer.log_dir))

    for data_iter_step, (samples, _) in enumerate(metric_logger.log_every(data_loader, print_freq, header)):

        # we use a per iteration (instead of per epoch) lr scheduler
        if data_iter_step % accum_iter == 0:
            lr_sched.adjust_learning_rate(optimizer, data_iter_step / len(data_loader) + epoch, args)

        resizer = Resize(args.input_size)
        samples = resizer(torch.cat(samples))
        samples = samples.to(device, non_blocking=True)

        with torch.cuda.amp.autocast():
            loss, _, _ = model(samples, mask_ratio=args.mask_ratio)

        loss_value = loss.item()

        if not math.isfinite(loss_value):
            print("Loss is {}, stopping training".format(loss_value), flush=True)
            sys.exit(1)

        loss = loss / accum_iter
        grad_norm = loss_scaler(loss, optimizer, parameters=model.parameters(),
                    update_grad=(data_iter_step + 1) % accum_iter == 0,
                    clip_grad=args.clip_grad)
        if (data_iter_step + 1) % accum_iter == 0:
            optimizer.zero_grad()

        torch.cuda.synchronize()

        metric_logger.update(loss=loss_value)

        lr = optimizer.param_groups[0]["lr"]
        metric_logger.update(lr=lr)

        if grad_norm is not None:
            metric_logger.update(grad_norm=grad_norm.item())

        loss_value_reduce = misc.all_reduce_mean(loss_value)
        if log_writer is not None and (data_iter_step + 1) % accum_iter == 0:
            """ We use epoch_1000x as the x-axis in tensorboard.
            This calibrates different curves when batch size changes.
            """
            if data_iter_step % 50 == 0:
                epoch_1000x = int((data_iter_step / len(data_loader) + epoch) * 1000)
                log_writer.add_scalar('train_loss', loss_value_reduce, epoch_1000x)
                log_writer.add_scalar('lr', lr, epoch_1000x)

    # gather the stats from all processes
    metric_logger.synchronize_between_processes()
    print("Averaged stats:", metric_logger)
    return {k: meter.global_avg for k, meter in metric_logger.meters.items()}