def train()

in sagemaker/sagemaker-inference/pytorch/code_mme/train.py [0:0]

• 52 lines of code
• 17 McCabe index (conditional complexity)

def train(args):
    is_distributed = len(args.hosts) > 1 and args.backend is not None
    logger.debug("Distributed training - {}".format(is_distributed))
    use_cuda = args.num_gpus > 0
    logger.debug("Number of gpus available - {}".format(args.num_gpus))
    kwargs = {'num_workers': 1, 'pin_memory': True} if use_cuda else {}
    device = torch.device("cuda" if use_cuda else "cpu")

    if is_distributed:
        # Initialize the distributed environment.
        world_size = len(args.hosts)
        os.environ['WORLD_SIZE'] = str(world_size)
        host_rank = args.hosts.index(args.current_host)
        os.environ['RANK'] = str(host_rank)
        dist.init_process_group(backend=args.backend, rank=host_rank, world_size=world_size)
        logger.info('Initialized the distributed environment: \'{}\' backend on {} nodes. '.format(
            args.backend, dist.get_world_size()) + 'Current host rank is {}. Number of gpus: {}'.format(
            dist.get_rank(), args.num_gpus))

    # set the seed for generating random numbers
    torch.manual_seed(args.seed)
    if use_cuda:
        torch.cuda.manual_seed(args.seed)

    train_loader = _get_train_data_loader(args.batch_size, args.data_dir, is_distributed, **kwargs)
    test_loader = _get_test_data_loader(args.test_batch_size, args.data_dir, **kwargs)

    logger.debug("Processes {}/{} ({:.0f}%) of train data".format(
        len(train_loader.sampler), len(train_loader.dataset),
        100. * len(train_loader.sampler) / len(train_loader.dataset)
    ))

    logger.debug("Processes {}/{} ({:.0f}%) of test data".format(
        len(test_loader.sampler), len(test_loader.dataset),
        100. * len(test_loader.sampler) / len(test_loader.dataset)
    ))

    model = Net().to(device)
    if is_distributed and use_cuda:
        # multi-machine multi-gpu case
        model = torch.nn.parallel.DistributedDataParallel(model)
    else:
        # single-machine multi-gpu case or single-machine or multi-machine cpu case
        model = torch.nn.DataParallel(model)

    optimizer = optim.SGD(model.parameters(), lr=args.lr, momentum=args.momentum)

    for epoch in range(1, args.epochs + 1):
        model.train()
        for batch_idx, (data, target) in enumerate(train_loader, 1):
            data, target = data.to(device), target.to(device)
            optimizer.zero_grad()
            output = model(data)
            loss = F.nll_loss(output, target)
            loss.backward()
            if is_distributed and not use_cuda:
                # average gradients manually for multi-machine cpu case only
                _average_gradients(model)
            optimizer.step()
            if batch_idx % args.log_interval == 0:
                logger.info('Train Epoch: {} [{}/{} ({:.0f}%)] Loss: {:.6f}'.format(
                    epoch, batch_idx * len(data), len(train_loader.sampler),
                    100. * batch_idx / len(train_loader), loss.item()))
        test(model, test_loader, device)
    save_model(model, args.model_dir)