main.py

import argparse
import os
import shutil
import time

import torch
from torch.autograd import Variable
import torch.nn as nn
import torch.nn.parallel
import torch.backends.cudnn as cudnn
import torch.distributed as dist
import torch.optim
import torch.utils.data
import torch.utils.data.distributed
import torchvision.models as models


try:
    from nvidia.dali.plugin.pytorch import DALIClassificationIterator
    from nvidia.dali.pipeline import Pipeline
    import nvidia.dali.ops as ops
    import nvidia.dali.types as types
except ImportError:
    raise ImportError("Please install DALI from https://www.github.com/NVIDIA/DALI to run this example.")

model_names = sorted(name for name in models.__dict__
                     if name.islower() and not name.startswith("__")
                     and callable(models.__dict__[name]))

parser = argparse.ArgumentParser(description='PyTorch ImageNet Training')
parser.add_argument('data', metavar='DIR', nargs='*',
                    help='path(s) to dataset (if one path is provided, it is assumed\n' +
                    'to have subdirectories named "train" and "val"; alternatively,\n' +
                    'train and val paths can be specified directly by providing both paths as arguments)')
parser.add_argument('--arch', '-a', metavar='ARCH', default='resnet18',
                    choices=model_names,
                    help='model architecture: ' +
                    ' | '.join(model_names) +
                    ' (default: resnet18)')
parser.add_argument('-j', '--workers', default=4, type=int, metavar='N',
                    help='number of data loading workers (default: 4)')
parser.add_argument('--epochs', default=90, type=int, metavar='N',
                    help='number of total epochs to run')
parser.add_argument('--start-epoch', default=0, type=int, metavar='N',
                    help='manual epoch number (useful on restarts)')
parser.add_argument('-b', '--batch-size', default=256, type=int,
                    metavar='N', help='mini-batch size (default: 256)')
parser.add_argument('--lr', '--learning-rate', default=0.1, type=float,
                    metavar='LR', help='initial learning rate')
parser.add_argument('--momentum', default=0.9, type=float, metavar='M',
                    help='momentum')
parser.add_argument('--weight-decay', '--wd', default=1e-4, type=float,
                    metavar='W', help='weight decay (default: 1e-4)')
parser.add_argument('--print-freq', '-p', default=10, type=int,
                    metavar='N', help='print frequency (default: 10)')
parser.add_argument('--resume', default='', type=str, metavar='PATH',
                    help='path to latest checkpoint (default: none)')
parser.add_argument('-e', '--evaluate', dest='evaluate', action='store_true',
                    help='evaluate model on validation set')
parser.add_argument('--pretrained', dest='pretrained', action='store_true',
                    help='use pre-trained model')
parser.add_argument('--fp16', action='store_true',
                    help='Run model fp16 mode.')
parser.add_argument('--dali_cpu', action='store_true',
                    help='Runs CPU based version of DALI pipeline.')
parser.add_argument('--static-loss-scale', type=float, default=1,
                    help='Static loss scale, positive power of 2 values can improve fp16 convergence.')
parser.add_argument('--dynamic-loss-scale', action='store_true',
                    help='Use dynamic loss scaling.  If supplied, this argument supersedes ' +
                    '--static-loss-scale.')
parser.add_argument('--prof', dest='prof', action='store_true',
                    help='Only run 10 iterations for profiling.')
parser.add_argument('-t', '--test', action='store_true',
                    help='Launch test mode with preset arguments')

parser.add_argument("--local_rank", default=0, type=int)

cudnn.benchmark = True

class HybridTrainPipe(Pipeline):
    def __init__(self, batch_size, num_threads, device_id, data_dir, crop, dali_cpu=False):
        super(HybridTrainPipe, self).__init__(batch_size, num_threads, device_id, seed=12 + device_id)
        self.input = ops.FileReader(file_root=data_dir, shard_id=args.local_rank, num_shards=args.world_size, random_shuffle=True)
        #let user decide which pipeline works him bets for RN version he runs
        if dali_cpu:
            dali_device = "cpu"
            self.decode = ops.HostDecoderRandomCrop(device=dali_device, output_type=types.RGB,
                                                    random_aspect_ratio=[0.8, 1.25],
                                                    random_area=[0.1, 1.0],
                                                    num_attempts=100)
        else:
            dali_device = "gpu"
            # This padding sets the size of the internal nvJPEG buffers to be able to handle all images from full-sized ImageNet
            # without additional reallocations
            self.decode = ops.nvJPEGDecoderRandomCrop(device="mixed", output_type=types.RGB, device_memory_padding=211025920, host_memory_padding=140544512,
                                                      random_aspect_ratio=[0.8, 1.25],
                                                      random_area=[0.1, 1.0],
                                                      num_attempts=100)
        self.res = ops.Resize(device=dali_device, resize_x=crop, resize_y=crop, interp_type=types.INTERP_TRIANGULAR)
        self.cmnp = ops.CropMirrorNormalize(device="gpu",
                                            output_dtype=types.FLOAT,
                                            output_layout=types.NCHW,
                                            crop=(crop, crop),
                                            image_type=types.RGB,
                                            mean=[0.485 * 255,0.456 * 255,0.406 * 255],
                                            std=[0.229 * 255,0.224 * 255,0.225 * 255])
        self.coin = ops.CoinFlip(probability=0.5)
        print('DALI "{0}" variant'.format(dali_device))

    def define_graph(self):
        rng = self.coin()
        self.jpegs, self.labels = self.input(name="Reader")
        images = self.decode(self.jpegs)
        images = self.res(images)
        output = self.cmnp(images.gpu(), mirror=rng)
        return [output, self.labels]

class HybridValPipe(Pipeline):
    def __init__(self, batch_size, num_threads, device_id, data_dir, crop, size):
        super(HybridValPipe, self).__init__(batch_size, num_threads, device_id, seed=12 + device_id)
        self.input = ops.FileReader(file_root=data_dir, shard_id=args.local_rank, num_shards=args.world_size, random_shuffle=False)
        self.decode = ops.nvJPEGDecoder(device="mixed", output_type=types.RGB)
        self.res = ops.Resize(device="gpu", resize_shorter=size, interp_type=types.INTERP_TRIANGULAR)
        self.cmnp = ops.CropMirrorNormalize(device="gpu",
                                            output_dtype=types.FLOAT,
                                            output_layout=types.NCHW,
                                            crop=(crop, crop),
                                            image_type=types.RGB,
                                            mean=[0.485 * 255,0.456 * 255,0.406 * 255],
                                            std=[0.229 * 255,0.224 * 255,0.225 * 255])

    def define_graph(self):
        self.jpegs, self.labels = self.input(name="Reader")
        images = self.decode(self.jpegs)
        images = self.res(images)
        output = self.cmnp(images)
        return [output, self.labels]

best_prec1 = 0
args = parser.parse_args()

# test mode, use default args for sanity test
if args.test:
    args.fp16 = False
    args.epochs = 1
    args.start_epoch = 0
    args.arch = 'resnet50'
    args.batch_size = 64
    args.data = []
    args.prof = True
    args.data.append('/data/imagenet/train-jpeg/')
    args.data.append('/data/imagenet/val-jpeg/')

if not len(args.data):
    raise Exception("error: too few arguments")

args.distributed = False
if 'WORLD_SIZE' in os.environ:
    args.distributed = int(os.environ['WORLD_SIZE']) > 1

# make apex optional
if args.fp16 or args.distributed:
    try:
        from apex.parallel import DistributedDataParallel as DDP
        from apex.fp16_utils import *
    except ImportError:
        raise ImportError("Please install apex from https://www.github.com/nvidia/apex to run this example.")

# item() is a recent addition, so this helps with backward compatibility.
def to_python_float(t):
    if hasattr(t, 'item'):
        return t.item()
    else:
        return t[0]

def main():
    global best_prec1, args

    args.gpu = 0
    args.world_size = 1

    if args.distributed:
        args.gpu = args.local_rank % torch.cuda.device_count()
        torch.cuda.set_device(args.gpu)
        torch.distributed.init_process_group(backend='nccl',
                                             init_method='env://')
        args.world_size = torch.distributed.get_world_size()

    if args.fp16:
        assert torch.backends.cudnn.enabled, "fp16 mode requires cudnn backend to be enabled."

    if args.static_loss_scale != 1.0:
        if not args.fp16:
            print("Warning:  if --fp16 is not used, static_loss_scale will be ignored.")

    # create model
    if args.pretrained:
        print("=> using pre-trained model '{}'".format(args.arch))
        model = models.__dict__[args.arch](pretrained=True)
    else:
        print("=> creating model '{}'".format(args.arch))
        model = models.__dict__[args.arch]()

    model = model.cuda()
    if args.fp16:
        model = network_to_half(model)
    if args.distributed:
        # shared param/delay all reduce turns off bucketing in DDP, for lower latency runs this can improve perf
        # for the older version of APEX please use shared_param, for newer one it is delay_allreduce
        model = DDP(model, delay_allreduce=True)

    # define loss function (criterion) and optimizer
    criterion = nn.CrossEntropyLoss().cuda()

    optimizer = torch.optim.SGD(model.parameters(), args.lr,
                                momentum=args.momentum,
                                weight_decay=args.weight_decay)
    if args.fp16:
        optimizer = FP16_Optimizer(optimizer,
                                   static_loss_scale=args.static_loss_scale,
                                   dynamic_loss_scale=args.dynamic_loss_scale)

    # optionally resume from a checkpoint
    if args.resume:
        if os.path.isfile(args.resume):
            print("=> loading checkpoint '{}'".format(args.resume))
            checkpoint = torch.load(args.resume, map_location=lambda storage, loc: storage.cuda(args.gpu))
            args.start_epoch = checkpoint['epoch']
            best_prec1 = checkpoint['best_prec1']
            model.load_state_dict(checkpoint['state_dict'])
            optimizer.load_state_dict(checkpoint['optimizer'])
            print("=> loaded checkpoint '{}' (epoch {})"
                  .format(args.resume, checkpoint['epoch']))
        else:
            print("=> no checkpoint found at '{}'".format(args.resume))

    # Data loading code
    if len(args.data) == 1:
        traindir = os.path.join(args.data[0], 'train')
        valdir = os.path.join(args.data[0], 'val')
    else:
        traindir = args.data[0]
        valdir= args.data[1]

    if(args.arch == "inception_v3"):
        crop_size = 299
        val_size = 320 # I chose this value arbitrarily, we can adjust.
    else:
        crop_size = 224
        val_size = 256

    pipe = HybridTrainPipe(batch_size=args.batch_size, num_threads=args.workers, device_id=args.local_rank, data_dir=traindir, crop=crop_size, dali_cpu=args.dali_cpu)
    pipe.build()
    train_loader = DALIClassificationIterator(pipe, size=int(pipe.epoch_size("Reader") / args.world_size))

    pipe = HybridValPipe(batch_size=args.batch_size, num_threads=args.workers, device_id=args.local_rank, data_dir=valdir, crop=crop_size, size=val_size)
    pipe.build()
    val_loader = DALIClassificationIterator(pipe, size=int(pipe.epoch_size("Reader") / args.world_size))

    if args.evaluate:
        validate(val_loader, model, criterion)
        return

    for epoch in range(args.start_epoch, args.epochs):
        # train for one epoch
        train(train_loader, model, criterion, optimizer, epoch)
        if args.prof:
            break
        # evaluate on validation set
        [prec1, prec5] = validate(val_loader, model, criterion)

        # remember best prec@1 and save checkpoint
        if args.local_rank == 0:
            is_best = prec1 > best_prec1
            best_prec1 = max(prec1, best_prec1)
            save_checkpoint({
                'epoch': epoch + 1,
                'arch': args.arch,
                'state_dict': model.state_dict(),
                'best_prec1': best_prec1,
                'optimizer': optimizer.state_dict(),
            }, is_best)
            if epoch == args.epochs - 1:
                print('##Top-1 {0}\n'
                      '##Top-5 {1}'.format(prec1, prec5))

        # reset DALI iterators
        train_loader.reset()
        val_loader.reset()

def train(train_loader, model, criterion, optimizer, epoch):
    batch_time = AverageMeter()
    data_time = AverageMeter()
    losses = AverageMeter()
    top1 = AverageMeter()
    top5 = AverageMeter()

    # switch to train mode
    model.train()
    end = time.time()

    for i, data in enumerate(train_loader):
        input = data[0]["data"]
        target = data[0]["label"].squeeze().cuda().long()
        train_loader_len = int(train_loader._size / args.batch_size)

        adjust_learning_rate(optimizer, epoch, i, train_loader_len)

        if args.prof:
            if i > 10:
                break
        # measure data loading time
        data_time.update(time.time() - end)

        input_var = Variable(input)
        target_var = Variable(target)

        # compute output
        output = model(input_var)
        loss = criterion(output, target_var)

        # measure accuracy and record loss
        prec1, prec5 = accuracy(output.data, target, topk=(1, 5))

        if args.distributed:
            reduced_loss = reduce_tensor(loss.data)
            prec1 = reduce_tensor(prec1)
            prec5 = reduce_tensor(prec5)
        else:
            reduced_loss = loss.data

        losses.update(to_python_float(reduced_loss), input.size(0))
        top1.update(to_python_float(prec1), input.size(0))
        top5.update(to_python_float(prec5), input.size(0))

        # compute gradient and do SGD step
        optimizer.zero_grad()
        if args.fp16:
            optimizer.backward(loss)
        else:
            loss.backward()
        optimizer.step()

        torch.cuda.synchronize()
        # measure elapsed time
        batch_time.update(time.time() - end)

        end = time.time()

        if args.local_rank == 0 and i % args.print_freq == 0 and i > 1:
            print('Epoch: [{0}][{1}/{2}]\t'
                  'Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
                  'Speed {3:.3f} ({4:.3f})\t'
                  'Data {data_time.val:.3f} ({data_time.avg:.3f})\t'
                  'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
                  'Prec@1 {top1.val:.3f} ({top1.avg:.3f})\t'
                  'Prec@5 {top5.val:.3f} ({top5.avg:.3f})'.format(
                   epoch, i, train_loader_len,
                   args.world_size * args.batch_size / batch_time.val,
                   args.world_size * args.batch_size / batch_time.avg,
                   batch_time=batch_time,
                   data_time=data_time, loss=losses, top1=top1, top5=top5))


def validate(val_loader, model, criterion):
    batch_time = AverageMeter()
    losses = AverageMeter()
    top1 = AverageMeter()
    top5 = AverageMeter()

    # switch to evaluate mode
    model.eval()

    end = time.time()

    for i, data in enumerate(val_loader):
        input = data[0]["data"]
        target = data[0]["label"].squeeze().cuda().long()
        val_loader_len = int(val_loader._size / args.batch_size)

        target = target.cuda(async=True)
        input_var = Variable(input)
        target_var = Variable(target)

        # compute output
        with torch.no_grad():
            output = model(input_var)
            loss = criterion(output, target_var)

        # measure accuracy and record loss
        prec1, prec5 = accuracy(output.data, target, topk=(1, 5))

        if args.distributed:
            reduced_loss = reduce_tensor(loss.data)
            prec1 = reduce_tensor(prec1)
            prec5 = reduce_tensor(prec5)
        else:
            reduced_loss = loss.data

        losses.update(to_python_float(reduced_loss), input.size(0))
        top1.update(to_python_float(prec1), input.size(0))
        top5.update(to_python_float(prec5), input.size(0))

        # measure elapsed time
        batch_time.update(time.time() - end)
        end = time.time()

        if args.local_rank == 0 and i % args.print_freq == 0:
            print('Test: [{0}/{1}]\t'
                  'Time {batch_time.val:.3f} ({batch_time.avg:.3f})\t'
                  'Speed {2:.3f} ({3:.3f})\t'
                  'Loss {loss.val:.4f} ({loss.avg:.4f})\t'
                  'Prec@1 {top1.val:.3f} ({top1.avg:.3f})\t'
                  'Prec@5 {top5.val:.3f} ({top5.avg:.3f})'.format(
                   i, val_loader_len,
                   args.world_size * args.batch_size / batch_time.val,
                   args.world_size * args.batch_size / batch_time.avg,
                   batch_time=batch_time, loss=losses,
                   top1=top1, top5=top5))

    print(' * Prec@1 {top1.avg:.3f} Prec@5 {top5.avg:.3f}'
          .format(top1=top1, top5=top5))

    return [top1.avg, top5.avg]


def save_checkpoint(state, is_best, filename='checkpoint.pth.tar'):
    torch.save(state, filename)
    if is_best:
        shutil.copyfile(filename, 'model_best.pth.tar')


class AverageMeter(object):
    """Computes and stores the average and current value"""
    def __init__(self):
        self.reset()

    def reset(self):
        self.val = 0
        self.avg = 0
        self.sum = 0
        self.count = 0

    def update(self, val, n=1):
        self.val = val
        self.sum += val * n
        self.count += n
        self.avg = self.sum / self.count


def adjust_learning_rate(optimizer, epoch, step, len_epoch):
    """LR schedule that should yield 76% converged accuracy with batch size 256"""
    factor = epoch // 30

    if epoch >= 80:
        factor = factor + 1

    lr = args.lr * (0.1 ** factor)

    """Warmup"""
    if epoch < 5:
        lr = lr * float(1 + step + epoch * len_epoch) / (5. * len_epoch)

    if(args.local_rank == 0 and step % args.print_freq == 0 and step > 1):
        print("Epoch = {}, step = {}, lr = {}".format(epoch, step, lr))

    for param_group in optimizer.param_groups:
        param_group['lr'] = lr


def accuracy(output, target, topk=(1,)):
    """Computes the precision@k for the specified values of k"""
    maxk = max(topk)
    batch_size = target.size(0)

    _, pred = output.topk(maxk, 1, True, True)
    pred = pred.t()
    correct = pred.eq(target.view(1, -1).expand_as(pred))

    res = []
    for k in topk:
        correct_k = correct[:k].view(-1).float().sum(0, keepdim=True)
        res.append(correct_k.mul_(100.0 / batch_size))
    return res


def reduce_tensor(tensor):
    rt = tensor.clone()
    dist.all_reduce(rt, op=dist.reduce_op.SUM)
    rt /= args.world_size
    return rt

if __name__ == '__main__':
    main()