add initial version of torchpack

examples/config_cifar10.py

@@ -0,0 +1,31 @@
+# model settings
+model = 'resnet18'
+# dataset settings
+data_root = '/mnt/SSD/dataset/cifar10'
+mean = [0.4914, 0.4822, 0.4465]
+std = [0.2023, 0.1994, 0.2010]
+batch_size = 64
+
+# optimizer and learning rate
+optimizer = dict(type='SGD', lr=0.1, momentum=0.9, weight_decay=5e-4)
+lr_policy = dict(policy='step', step=2)
+
+# runtime settings
+work_dir = './demo'
+gpus = range(2)
+data_workers = 2  # data workers per gpu
+checkpoint_cfg = dict(interval=1)  # save checkpoint at every epoch
+workflow = [('train', 1), ('val', 1)]
+max_epoch = 6
+resume_from = None
+load_from = None
+
+# logging settings
+log_level = 'INFO'
+log_cfg = dict(
+    # log at every 50 iterations
+    interval=50,
+    hooks=[
+        dict(type='TextLoggerHook'),
+        # dict(type='TensorboardLoggerHook', log_dir=work_dir + '/log'),
+    ])

examples/resnet_cifar.py

@@ -0,0 +1,132 @@
+# copied from https://github.com/kuangliu/pytorch-cifar/blob/master/models/resnet.py
+
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+class BasicBlock(nn.Module):
+    expansion = 1
+
+    def __init__(self, in_planes, planes, stride=1):
+        super(BasicBlock, self).__init__()
+        self.conv1 = nn.Conv2d(
+            in_planes,
+            planes,
+            kernel_size=3,
+            stride=stride,
+            padding=1,
+            bias=False)
+        self.bn1 = nn.BatchNorm2d(planes)
+        self.conv2 = nn.Conv2d(
+            planes, planes, kernel_size=3, stride=1, padding=1, bias=False)
+        self.bn2 = nn.BatchNorm2d(planes)
+
+        self.shortcut = nn.Sequential()
+        if stride != 1 or in_planes != self.expansion * planes:
+            self.shortcut = nn.Sequential(
+                nn.Conv2d(
+                    in_planes,
+                    self.expansion * planes,
+                    kernel_size=1,
+                    stride=stride,
+                    bias=False), nn.BatchNorm2d(self.expansion * planes))
+
+    def forward(self, x):
+        out = F.relu(self.bn1(self.conv1(x)))
+        out = self.bn2(self.conv2(out))
+        out += self.shortcut(x)
+        out = F.relu(out)
+        return out
+
+
+class Bottleneck(nn.Module):
+    expansion = 4
+
+    def __init__(self, in_planes, planes, stride=1):
+        super(Bottleneck, self).__init__()
+        self.conv1 = nn.Conv2d(in_planes, planes, kernel_size=1, bias=False)
+        self.bn1 = nn.BatchNorm2d(planes)
+        self.conv2 = nn.Conv2d(
+            planes,
+            planes,
+            kernel_size=3,
+            stride=stride,
+            padding=1,
+            bias=False)
+        self.bn2 = nn.BatchNorm2d(planes)
+        self.conv3 = nn.Conv2d(
+            planes, self.expansion * planes, kernel_size=1, bias=False)
+        self.bn3 = nn.BatchNorm2d(self.expansion * planes)
+
+        self.shortcut = nn.Sequential()
+        if stride != 1 or in_planes != self.expansion * planes:
+            self.shortcut = nn.Sequential(
+                nn.Conv2d(
+                    in_planes,
+                    self.expansion * planes,
+                    kernel_size=1,
+                    stride=stride,
+                    bias=False), nn.BatchNorm2d(self.expansion * planes))
+
+    def forward(self, x):
+        out = F.relu(self.bn1(self.conv1(x)))
+        out = F.relu(self.bn2(self.conv2(out)))
+        out = self.bn3(self.conv3(out))
+        out += self.shortcut(x)
+        out = F.relu(out)
+        return out
+
+
+class ResNet(nn.Module):
+
+    def __init__(self, block, num_blocks, num_classes=10):
+        super(ResNet, self).__init__()
+        self.in_planes = 64
+
+        self.conv1 = nn.Conv2d(
+            3, 64, kernel_size=3, stride=1, padding=1, bias=False)
+        self.bn1 = nn.BatchNorm2d(64)
+        self.layer1 = self._make_layer(block, 64, num_blocks[0], stride=1)
+        self.layer2 = self._make_layer(block, 128, num_blocks[1], stride=2)
+        self.layer3 = self._make_layer(block, 256, num_blocks[2], stride=2)
+        self.layer4 = self._make_layer(block, 512, num_blocks[3], stride=2)
+        self.linear = nn.Linear(512 * block.expansion, num_classes)
+
+    def _make_layer(self, block, planes, num_blocks, stride):
+        strides = [stride] + [1] * (num_blocks - 1)
+        layers = []
+        for stride in strides:
+            layers.append(block(self.in_planes, planes, stride))
+            self.in_planes = planes * block.expansion
+        return nn.Sequential(*layers)
+
+    def forward(self, x):
+        out = F.relu(self.bn1(self.conv1(x)))
+        out = self.layer1(out)
+        out = self.layer2(out)
+        out = self.layer3(out)
+        out = self.layer4(out)
+        out = F.avg_pool2d(out, 4)
+        out = out.view(out.size(0), -1)
+        out = self.linear(out)
+        return out
+
+
+def resnet18():
+    return ResNet(BasicBlock, [2, 2, 2, 2])
+
+
+def resnet34():
+    return ResNet(BasicBlock, [3, 4, 6, 3])
+
+
+def resnet50():
+    return ResNet(Bottleneck, [3, 4, 6, 3])
+
+
+def resnet101():
+    return ResNet(Bottleneck, [3, 4, 23, 3])
+
+
+def resnet152():
+    return ResNet(Bottleneck, [3, 8, 36, 3])

examples/train_cifar10.py

@@ -0,0 +1,102 @@
+from argparse import ArgumentParser
+from collections import OrderedDict
+
+import torch
+import torch.nn.functional as F
+from mmcv import Config
+from mmcv.torchpack import Runner
+from torchvision import datasets, transforms
+
+import resnet_cifar
+
+
+def accuracy(output, target, topk=(1, )):
+    """Computes the precision@k for the specified values of k"""
+    with torch.no_grad():
+        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 batch_processor(model, data, train_mode):
+    img, label = data
+    label = label.cuda(non_blocking=True)
+    pred = model(img)
+    loss = F.cross_entropy(pred, label)
+    acc_top1, acc_top5 = accuracy(pred, label, topk=(1, 5))
+    log_vars = OrderedDict()
+    log_vars['loss'] = loss.item()
+    log_vars['acc_top1'] = acc_top1.item()
+    log_vars['acc_top5'] = acc_top5.item()
+    outputs = dict(loss=loss, log_vars=log_vars, num_samples=img.size(0))
+    return outputs
+
+
+def parse_args():
+    parser = ArgumentParser(description='Train CIFAR-10 classification')
+    parser.add_argument('config', help='train config file path')
+    return parser.parse_args()
+
+
+def main():
+    args = parse_args()
+    cfg = Config.fromfile(args.config)
+    model = getattr(resnet_cifar, cfg.model)()
+    model = torch.nn.DataParallel(model, device_ids=cfg.gpus).cuda()
+
+    normalize = transforms.Normalize(mean=cfg.mean, std=cfg.std)
+    train_dataset = datasets.CIFAR10(
+        root=cfg.data_root,
+        train=True,
+        transform=transforms.Compose([
+            transforms.RandomCrop(32, padding=4),
+            transforms.RandomHorizontalFlip(),
+            transforms.ToTensor(),
+            normalize,
+        ]))
+    val_dataset = datasets.CIFAR10(
+        root=cfg.data_root,
+        transform=transforms.Compose([
+            transforms.ToTensor(),
+            normalize,
+        ]))
+
+    num_workers = cfg.data_workers * len(cfg.gpus)
+    train_loader = torch.utils.data.DataLoader(
+        train_dataset,
+        batch_size=cfg.batch_size,
+        shuffle=True,
+        num_workers=num_workers,
+        pin_memory=True)
+    val_loader = torch.utils.data.DataLoader(
+        val_dataset,
+        batch_size=cfg.batch_size,
+        shuffle=False,
+        num_workers=num_workers,
+        pin_memory=True)
+
+    runner = Runner(model, cfg.optimizer, batch_processor, cfg.work_dir)
+    runner.register_default_hooks(
+        lr_config=cfg.lr_policy,
+        checkpoint_config=cfg.checkpoint_cfg,
+        log_config=cfg.log_cfg)
+
+    if cfg.get('resume_from') is not None:
+        runner.resume(cfg.resume_from)
+    elif cfg.get('load_from') is not None:
+        runner.load_checkpoint(cfg.load_from)
+
+    runner.run([train_loader, val_loader], cfg.workflow, cfg.max_epoch)
+
+
+if __name__ == '__main__':
+    main()

mmcv/torchpack/__init__.py

@@ -0,0 +1,5 @@
+from .hooks import *
+from .io import *
+from .parallel import *
+from .runner import *
+from .utils import *

mmcv/torchpack/hooks/__init__.py

@@ -0,0 +1,7 @@
+from .hook import Hook
+from .checkpoint_saver import CheckpointSaverHook
+from .closure import ClosureHook
+from .lr_updater import LrUpdaterHook
+from .optimizer_stepper import OptimizerStepperHook
+from .iter_timer import IterTimerHook
+from .logger import *

mmcv/torchpack/hooks/checkpoint_saver.py

@@ -0,0 +1,25 @@
+from .hook import Hook
+from ..utils import master_only
+
+
+class CheckpointSaverHook(Hook):
+
+    def __init__(self,
+                 interval=-1,
+                 save_optimizer=True,
+                 out_dir=None,
+                 **kwargs):
+        self.interval = interval
+        self.save_optimizer = save_optimizer
+        self.out_dir = out_dir
+        self.args = kwargs
+
+    @master_only
+    def after_train_epoch(self, runner):
+        if not self.every_n_epochs(runner, self.interval):
+            return
+
+        if not self.out_dir:
+            self.out_dir = runner.work_dir
+        runner.save_checkpoint(
+            self.out_dir, save_optimizer=self.save_optimizer, **self.args)

mmcv/torchpack/hooks/closure.py

@@ -0,0 +1,9 @@
+from .hook import Hook
+
+
+class ClosureHook(Hook):
+
+    def __init__(self, fn_name, fn):
+        assert hasattr(self, fn_name)
+        assert callable(fn)
+        setattr(self, fn_name, fn)

mmcv/torchpack/hooks/hook.py

@@ -0,0 +1,55 @@
+class Hook(object):
+
+    def before_run(self, runner):
+        pass
+
+    def after_run(self, runner):
+        pass
+
+    def before_epoch(self, runner):
+        pass
+
+    def after_epoch(self, runner):
+        pass
+
+    def before_iter(self, runner):
+        pass
+
+    def after_iter(self, runner):
+        pass
+
+    def before_train_epoch(self, runner):
+        self.before_epoch(runner)
+
+    def before_val_epoch(self, runner):
+        self.before_epoch(runner)
+
+    def after_train_epoch(self, runner):
+        self.after_epoch(runner)
+
+    def after_val_epoch(self, runner):
+        self.after_epoch(runner)
+
+    def before_train_iter(self, runner):
+        self.before_iter(runner)
+
+    def before_val_iter(self, runner):
+        self.before_iter(runner)
+
+    def after_train_iter(self, runner):
+        self.after_iter(runner)
+
+    def after_val_iter(self, runner):
+        self.after_iter(runner)
+
+    def every_n_epochs(self, runner, n):
+        return (runner.epoch + 1) % n == 0 if n > 0 else False
+
+    def every_n_inner_iters(self, runner, n):
+        return (runner.inner_iter + 1) % n == 0 if n > 0 else False
+
+    def every_n_iters(self, runner, n):
+        return (runner.iter + 1) % n == 0 if n > 0 else False
+
+    def end_of_epoch(self, runner):
+        return runner.inner_iter + 1 == len(runner.data_loader)

mmcv/torchpack/hooks/iter_timer.py

@@ -0,0 +1,16 @@
+import time
+
+from .hook import Hook
+
+
+class IterTimerHook(Hook):
+
+    def before_epoch(self, runner):
+        self.t = time.time()
+
+    def before_iter(self, runner):
+        runner.log_buffer.update({'data_time': time.time() - self.t})
+
+    def after_iter(self, runner):
+        runner.log_buffer.update({'time': time.time() - self.t})
+        self.t = time.time()

mmcv/torchpack/hooks/logger/__init__.py

@@ -0,0 +1,4 @@
+from .base import LoggerHook
+from .pavi import PaviClient, PaviLoggerHook
+from .tensorboard import TensorboardLoggerHook
+from .text import TextLoggerHook

mmcv/torchpack/hooks/logger/base.py

@@ -0,0 +1,49 @@
+from abc import ABCMeta, abstractmethod
+
+from ..hook import Hook
+
+
+class LoggerHook(Hook):
+    """Base class for logger hooks."""
+
+    __metaclass__ = ABCMeta
+
+    def __init__(self, interval=10, ignore_last=True, reset_flag=False):
+        self.interval = interval
+        self.ignore_last = ignore_last
+        self.reset_flag = reset_flag
+
+    @abstractmethod
+    def log(self, runner):
+        pass
+
+    def before_run(self, runner):
+        for hook in runner.hooks[::-1]:
+            if isinstance(hook, LoggerHook):
+                hook.reset_flag = True
+                break
+
+    def before_epoch(self, runner):
+        runner.log_buffer.clear()  # clear logs of last epoch
+
+    def after_train_iter(self, runner):
+        if self.every_n_inner_iters(runner, self.interval):
+            runner.log_buffer.average(self.interval)
+        elif self.end_of_epoch(runner) and not self.ignore_last:
+            # not precise but more stable
+            runner.log_buffer.average(self.interval)
+
+        if runner.log_buffer.ready:
+            self.log(runner)
+            if self.reset_flag:
+                runner.log_buffer.clear_output()
+
+    def after_train_epoch(self, runner):
+        if runner.log_buffer.ready:
+            self.log(runner)
+
+    def after_val_epoch(self, runner):
+        runner.log_buffer.average()
+        self.log(runner)
+        if self.reset_flag:
+            runner.log_buffer.clear_output()

mmcv/torchpack/hooks/logger/pavi.py

@@ -0,0 +1,147 @@
+from __future__ import print_function
+
+import os
+import time
+from datetime import datetime
+from threading import Thread
+
+import requests
+from six.moves.queue import Empty, Queue
+
+from .base import LoggerHook
+from ...utils import master_only, get_host_info
+
+
+class PaviClient(object):
+
+    def __init__(self, url, username=None, password=None, instance_id=None):
+        self.url = url
+        self.username = self._get_env_var(username, 'PAVI_USERNAME')
+        self.password = self._get_env_var(password, 'PAVI_PASSWORD')
+        self.instance_id = instance_id
+        self.log_queue = None
+
+    def _get_env_var(self, var, env_var):
+        if var is not None:
+            return str(var)
+
+        var = os.getenv(env_var)
+        if not var:
+            raise ValueError(
+                '"{}" is neither specified nor defined as env variables'.
+                format(env_var))
+        return var
+
+    def connect(self,
+                model_name,
+                work_dir=None,
+                info=dict(),
+                timeout=5,
+                logger=None):
+        if logger:
+            log_info = logger.info
+            log_error = logger.error
+        else:
+            log_info = log_error = print
+        log_info('connecting pavi service {}...'.format(self.url))
+        post_data = dict(
+            time=str(datetime.now()),
+            username=self.username,
+            password=self.password,
+            instance_id=self.instance_id,
+            model=model_name,
+            work_dir=os.path.abspath(work_dir) if work_dir else '',
+            session_file=info.get('session_file', ''),
+            session_text=info.get('session_text', ''),
+            model_text=info.get('model_text', ''),
+            device=get_host_info())
+        try:
+            response = requests.post(self.url, json=post_data, timeout=timeout)
+        except Exception as ex:
+            log_error('fail to connect to pavi service: {}'.format(ex))
+        else:
+            if response.status_code == 200:
+                self.instance_id = response.text
+                log_info('pavi service connected, instance_id: {}'.format(
+                    self.instance_id))
+                self.log_queue = Queue()
+                self.log_thread = Thread(target=self.post_worker_fn)
+                self.log_thread.daemon = True
+                self.log_thread.start()
+                return True
+            else:
+                log_error('fail to connect to pavi service, status code: '
+                          '{}, err message: {}'.format(response.status_code,
+                                                       response.reason))
+        return False
+
+    def post_worker_fn(self, max_retry=3, queue_timeout=1, req_timeout=3):
+        while True:
+            try:
+                log = self.log_queue.get(timeout=queue_timeout)
+            except Empty:
+                time.sleep(1)
+            except Exception as ex:
+                print('fail to get logs from queue: {}'.format(ex))
+            else:
+                retry = 0
+                while retry < max_retry:
+                    try:
+                        response = requests.post(
+                            self.url, json=log, timeout=req_timeout)
+                    except Exception as ex:
+                        retry += 1
+                        print('error when posting logs to pavi: {}'.format(ex))
+                    else:
+                        status_code = response.status_code
+                        if status_code == 200:
+                            break
+                        else:
+                            print('unexpected status code: %d, err msg: %s',
+                                  status_code, response.reason)
+                            retry += 1
+                if retry == max_retry:
+                    print('fail to send logs of iteration %d', log['iter_num'])
+
+    def log(self, phase, iter, outputs):
+        if self.log_queue is not None:
+            logs = {
+                'time': str(datetime.now()),
+                'instance_id': self.instance_id,
+                'flow_id': phase,
+                'iter_num': iter,
+                'outputs': outputs,
+                'msg': ''
+            }
+            self.log_queue.put(logs)
+
+
+class PaviLoggerHook(LoggerHook):
+
+    def __init__(self,
+                 url,
+                 username=None,
+                 password=None,
+                 instance_id=None,
+                 interval=10,
+                 reset_meter=True,
+                 ignore_last=True):
+        self.pavi = PaviClient(url, username, password, instance_id)
+        super(PaviLoggerHook, self).__init__(interval, reset_meter,
+                                             ignore_last)
+
+    @master_only
+    def connect(self,
+                model_name,
+                work_dir=None,
+                info=dict(),
+                timeout=5,
+                logger=None):
+        return self.pavi.connect(model_name, work_dir, info, timeout, logger)
+
+    @master_only
+    def log(self, runner):
+        log_outs = runner.log_buffer.output.copy()
+        log_outs.pop('time', None)
+        log_outs.pop('data_time', None)
+        self.pavi.log(runner.mode, runner.iter, log_outs)

mmcv/torchpack/hooks/logger/tensorboard.py

@@ -0,0 +1,37 @@
+from .base import LoggerHook
+from ...utils import master_only
+
+
+class TensorboardLoggerHook(LoggerHook):
+
+    def __init__(self,
+                 log_dir,
+                 interval=10,
+                 reset_meter=True,
+                 ignore_last=True):
+        super(TensorboardLoggerHook, self).__init__(interval, reset_meter,
+                                                    ignore_last)
+        self.log_dir = log_dir
+
+    @master_only
+    def before_run(self, runner):
+        try:
+            from tensorboardX import SummaryWriter
+        except ImportError:
+            raise ImportError('Please install tensorflow and tensorboardX '
+                              'to use TensorboardLoggerHook.')
+        else:
+            self.writer = SummaryWriter(self.log_dir)
+
+    @master_only
+    def log(self, runner):
+        for var in runner.log_buffer.output:
+            if var in ['time', 'data_time']:
+                continue
+            tag = '{}/{}'.format(var, runner.mode)
+            self.writer.add_scalar(tag, runner.log_buffer.output[var],
+                                   runner.iter)
+
+    @master_only
+    def after_run(self, runner):
+        self.writer.close()

mmcv/torchpack/hooks/logger/text.py

@@ -0,0 +1,26 @@
+from .base import LoggerHook
+
+
+class TextLoggerHook(LoggerHook):
+
+    def log(self, runner):
+        if runner.mode == 'train':
+            lr_str = ', '.join(
+                ['{:.5f}'.format(lr) for lr in runner.current_lr()])
+            log_str = 'Epoch [{}][{}/{}]\tlr: {}, '.format(
+                runner.epoch + 1, runner.inner_iter + 1,
+                len(runner.data_loader), lr_str)
+        else:
+            log_str = 'Epoch({}) [{}][{}]\t'.format(runner.mode, runner.epoch,
+                                                    runner.inner_iter + 1)
+        if 'time' in runner.log_buffer.output:
+            log_str += (
+                'time: {log[time]:.3f}, data_time: {log[data_time]:.3f}, '.
+                format(log=runner.log_buffer.output))
+        log_items = []
+        for name, val in runner.log_buffer.output.items():
+            if name in ['time', 'data_time']:
+                continue
+            log_items.append('{}: {:.4f}'.format(name, val))
+        log_str += ', '.join(log_items)
+        runner.logger.info(log_str)

mmcv/torchpack/hooks/lr_updater.py

@@ -0,0 +1,163 @@
+from __future__ import division
+
+from .hook import Hook
+
+
+class LrUpdaterHook(Hook):
+
+    def __init__(self,
+                 by_epoch=True,
+                 warmup=None,
+                 warmup_iters=0,
+                 warmup_ratio=0.1,
+                 **kwargs):
+        # validate the "warmup" argument
+        if warmup is not None:
+            if warmup not in ['constant', 'linear', 'exp']:
+                raise ValueError(
+                    '"{}" is not a supported type for warming up, valid types'
+                    ' are "constant" and "linear"'.format(warmup))
+        if warmup is not None:
+            assert warmup_iters > 0, \
+                '"warmup_iters" must be a positive integer'
+            assert 0 < warmup_ratio <= 1.0, \
+                '"warmup_ratio" must be in range (0,1]'
+
+        self.by_epoch = by_epoch
+        self.warmup = warmup
+        self.warmup_iters = warmup_iters
+        self.warmup_ratio = warmup_ratio
+
+        self.base_lr = []  # initial lr for all param groups
+        self.regular_lr = []  # expected lr if no warming up is performed
+
+    def _set_lr(self, runner, lr_groups):
+        for param_group, lr in zip(runner.optimizer.param_groups, lr_groups):
+            param_group['lr'] = lr
+
+    def get_lr(self, runner, base_lr):
+        raise NotImplementedError
+
+    def get_regular_lr(self, runner):
+        return [self.get_lr(runner, _base_lr) for _base_lr in self.base_lr]
+
+    def get_warmup_lr(self, cur_iters):
+        if self.warmup == 'constant':
+            warmup_lr = [_lr * self.warmup_ratio for _lr in self.regular_lr]
+        elif self.warmup == 'linear':
+            k = (1 - cur_iters / self.warmup_iters) * (1 - self.warmup_ratio)
+            warmup_lr = [_lr * (1 - k) for _lr in self.regular_lr]
+        elif self.warmup == 'exp':
+            k = self.warmup_ratio**(1 - cur_iters / self.warmup_iters)
+            warmup_lr = [_lr * k for _lr in self.regular_lr]
+        return warmup_lr
+
+    def before_run(self, runner):
+        # NOTE: when resuming from a checkpoint, if 'initial_lr' is not saved,
+        # it will be set according to the optimizer params
+        for group in runner.optimizer.param_groups:
+            group.setdefault('initial_lr', group['lr'])
+        self.base_lr = [
+            group['initial_lr'] for group in runner.optimizer.param_groups
+        ]
+
+    def before_train_epoch(self, runner):
+        if not self.by_epoch:
+            return
+        self.regular_lr = self.get_regular_lr(runner)
+        self._set_lr(runner, self.regular_lr)
+
+    def before_train_iter(self, runner):
+        cur_iter = runner.iter
+        if not self.by_epoch:
+            self.regular_lr = self.get_regular_lr(runner)
+            if self.warmup is None or cur_iter >= self.warmup_iters:
+                self._set_lr(runner, self.regular_lr)
+            else:
+                warmup_lr = self.get_warmup_lr(cur_iter)
+                self._set_lr(runner, warmup_lr)
+        elif self.by_epoch:
+            if self.warmup is None or cur_iter > self.warmup_iters:
+                return
+            elif cur_iter == self.warmup_iters:
+                self._set_lr(runner, self.regular_lr)
+            else:
+                warmup_lr = self.get_warmup_lr(cur_iter)
+                self._set_lr(runner, warmup_lr)
+
+
+class FixedLrUpdaterHook(LrUpdaterHook):
+
+    def __init__(self, **kwargs):
+        super(FixedLrUpdaterHook, self).__init__(**kwargs)
+
+    def get_lr(self, runner, base_lr):
+        return base_lr
+
+
+class StepLrUpdaterHook(LrUpdaterHook):
+
+    def __init__(self, step, gamma=0.1, **kwargs):
+        assert isinstance(step, (list, int))
+        if isinstance(step, list):
+            for s in step:
+                assert isinstance(s, int) and s > 0
+        elif isinstance(step, int):
+            assert step > 0
+        else:
+            raise TypeError('"step" must be a list or integer')
+        self.step = step
+        self.gamma = gamma
+        super(StepLrUpdaterHook, self).__init__(**kwargs)
+
+    def get_lr(self, runner, base_lr):
+        progress = runner.epoch if self.by_epoch else runner.iter
+
+        if isinstance(self.step, int):
+            return base_lr * (self.gamma**(progress // self.step))
+
+        exp = len(self.step)
+        for i, s in enumerate(self.step):
+            if progress < s:
+                exp = i
+                break
+        return base_lr * self.gamma**exp
+
+
+class ExpLrUpdaterHook(LrUpdaterHook):
+
+    def __init__(self, gamma, **kwargs):
+        self.gamma = gamma
+        super(ExpLrUpdaterHook, self).__init__(**kwargs)
+
+    def get_lr(self, runner, base_lr):
+        progress = runner.epoch if self.by_epoch else runner.iter
+        return base_lr * self.gamma**progress
+
+
+class PolyLrUpdaterHook(LrUpdaterHook):
+
+    def __init__(self, power=1., **kwargs):
+        self.power = power
+        super(PolyLrUpdaterHook, self).__init__(**kwargs)
+
+    def get_lr(self, runner, base_lr):
+        if self.by_epoch:
+            progress = runner.epoch
+            max_progress = runner.max_epochs
+        else:
+            progress = runner.iter
+            max_progress = runner.max_iters
+        return base_lr * (1 - progress / max_progress)**self.power
+
+
+class InvLrUpdaterHook(LrUpdaterHook):
+
+    def __init__(self, gamma, power=1., **kwargs):
+        self.gamma = gamma
+        self.power = power
+        super(InvLrUpdaterHook, self).__init__(**kwargs)
+
+    def get_lr(self, runner, base_lr):
+        progress = runner.epoch if self.by_epoch else runner.iter
+        return base_lr * (1 + self.gamma * progress)**(-self.power)

mmcv/torchpack/hooks/optimizer_stepper.py

@@ -0,0 +1,21 @@
+from torch.nn.utils import clip_grad
+
+from .hook import Hook
+
+
+class OptimizerStepperHook(Hook):
+
+    def __init__(self, grad_clip=False, max_norm=35, norm_type=2):
+        self.grad_clip = grad_clip
+        self.max_norm = max_norm
+        self.norm_type = norm_type
+
+    def after_train_iter(self, runner):
+        runner.optimizer.zero_grad()
+        runner.outputs['loss'].backward()
+        if self.grad_clip:
+            clip_grad.clip_grad_norm_(
+                filter(lambda p: p.requires_grad, runner.model.parameters()),
+                max_norm=self.max_norm,
+                norm_type=self.norm_type)
+        runner.optimizer.step()

mmcv/torchpack/io.py

@@ -0,0 +1,157 @@
+import os.path as osp
+import time
+from collections import OrderedDict
+
+import mmcv
+import torch
+from torch.nn.parallel import DataParallel, DistributedDataParallel
+from torch.utils import model_zoo
+
+
+def load_state_dict(module, state_dict, strict=False, logger=None):
+    """Load state_dict to a module.
+
+    This method is modified from :meth:`torch.nn.Module.load_state_dict`.
+    Default value for ``strict`` is set to ``False`` and the message for
+    param mismatch will be shown even if strict is False.
+
+    Args:
+        module (Module): Module that receives the state_dict.
+        state_dict (OrderedDict): Weights.
+        strict (bool): whether to strictly enforce that the keys
+            in :attr:`state_dict` match the keys returned by this module's
+            :meth:`~torch.nn.Module.state_dict` function. Default: ``False``.
+        logger (:obj:`logging.Logger`, optional): Logger to log the error
+            message. If not specified, print function will be used.
+    """
+    unexpected_keys = []
+    own_state = module.state_dict()
+    for name, param in state_dict.items():
+        if name not in own_state:
+            unexpected_keys.append(name)
+            continue
+        if isinstance(param, torch.nn.Parameter):
+            # backwards compatibility for serialized parameters
+            param = param.data
+
+        try:
+            own_state[name].copy_(param)
+        except Exception:
+            raise RuntimeError('While copying the parameter named {}, '
+                               'whose dimensions in the model are {} and '
+                               'whose dimensions in the checkpoint are {}.'
+                               .format(name, own_state[name].size(),
+                                       param.size()))
+    missing_keys = set(own_state.keys()) - set(state_dict.keys())
+
+    err_msg = []
+    if unexpected_keys:
+        err_msg.append('unexpected key in source state_dict: {}\n'.format(
+            ', '.join(unexpected_keys)))
+    if missing_keys:
+        err_msg.append('missing keys in source state_dict: {}\n'.format(
+            ', '.join(missing_keys)))
+    err_msg = '\n'.join(err_msg)
+    if err_msg:
+        if strict:
+            raise RuntimeError(err_msg)
+        elif logger is not None:
+            logger.warn(err_msg)
+        else:
+            print(err_msg)
+
+
+def load_checkpoint(model,
+                    filename,
+                    map_location=None,
+                    strict=False,
+                    logger=None):
+    """Load checkpoint from a file or URI.
+
+    Args:
+        model (Module): Module to load checkpoint.
+        filename (str): Either a filepath or URL or modelzoll://xxxxxxx.
+        map_location (str): Same as :func:`torch.load`.
+        strict (bool): Whether to allow different params for the model and
+            checkpoint.
+        logger (:mod:`logging.Logger` or None): The logger for error message.
+
+    Returns:
+        dict or OrderedDict: The loaded checkpoint.
+    """
+    # load checkpoint from modelzoo or file or url
+    if filename.startswith('modelzoo://'):
+        from torchvision.models.resnet import model_urls
+        model_name = filename[11:]
+        checkpoint = model_zoo.load_url(model_urls[model_name])
+    elif filename.startswith(('http://', 'https://')):
+        checkpoint = model_zoo.load_url(filename)
+    else:
+        if not osp.isfile(filename):
+            raise IOError('{} is not a checkpoint file'.format(filename))
+        checkpoint = torch.load(filename, map_location=map_location)
+    # get state_dict from checkpoint
+    if isinstance(checkpoint, OrderedDict):
+        state_dict = checkpoint
+    elif isinstance(checkpoint, dict) and 'state_dict' in checkpoint:
+        state_dict = checkpoint['state_dict']
+    else:
+        raise RuntimeError(
+            'No state_dict found in checkpoint file {}'.format(filename))
+    # strip prefix of state_dict
+    if list(state_dict.keys())[0].startswith('module.'):
+        state_dict = {k[7:]: v for k, v in checkpoint['state_dict'].items()}
+    # load state_dict
+    if isinstance(model, (DataParallel, DistributedDataParallel)):
+        load_state_dict(model.module, state_dict, strict, logger)
+    else:
+        load_state_dict(model, state_dict, strict, logger)
+    return checkpoint
+
+
+def weights_to_cpu(state_dict):
+    """Copy a model state_dict to cpu.
+
+    Args:
+        state_dict (OrderedDict): Model weights on GPU.
+
+    Returns:
+        OrderedDict: Model weights on GPU.
+    """
+    state_dict_cpu = OrderedDict()
+    for key, val in state_dict.items():
+        state_dict_cpu[key] = val.cpu()
+    return state_dict_cpu
+
+
+def save_checkpoint(model, filename, optimizer=None, meta=None):
+    """Save checkpoint to file.
+
+    The checkpoint will have 3 fields: ``meta``, ``state_dict`` and
+    ``optimizer``. By default ``meta`` will contain version and time info.
+
+    Args:
+        model (Module): Module whose params are to be saved.
+        filename (str): Checkpoint filename.
+        optimizer (:obj:`Optimizer`, optional): Optimizer to be saved.
+        meta (dict, optional): Metadata to be saved in checkpoint.
+    """
+    if meta is None:
+        meta = {}
+    elif not isinstance(meta, dict):
+        raise TypeError('meta must be a dict or None, but got {}'.format(
+            type(meta)))
+    meta.update(mmcv_version=mmcv.__version__, time=time.asctime())
+
+    mmcv.mkdir_or_exist(osp.dirname(filename))
+    if isinstance(model, (DataParallel, DistributedDataParallel)):
+        model = model.module
+
+    checkpoint = {
+        'meta': meta,
+        'state_dict': weights_to_cpu(model.state_dict())
+    }
+    if optimizer is not None:
+        checkpoint['optimizer'] = optimizer.state_dict()
+
+    torch.save(checkpoint, filename)

mmcv/torchpack/parallel.py

@@ -0,0 +1,74 @@
+import multiprocessing
+
+import torch
+
+from .io import load_checkpoint
+
+
+def worker_func(model_cls, model_kwargs, checkpoint, dataset, data_func,
+                gpu_id, idx_queue, result_queue):
+    model = model_cls(**model_kwargs)
+    load_checkpoint(model, checkpoint, map_location='cpu')
+    torch.cuda.set_device(gpu_id)
+    model.cuda()
+    model.eval()
+    with torch.no_grad():
+        while True:
+            idx = idx_queue.get()
+            data = dataset[idx]
+            result = model(**data_func(data, gpu_id))
+            result_queue.put((idx, result))
+
+
+def parallel_test(model_cls,
+                  model_kwargs,
+                  checkpoint,
+                  dataset,
+                  data_func,
+                  gpus,
+                  workers_per_gpu=1):
+    """Parallel testing on multiple GPUs.
+
+    Args:
+        model_cls (type): Model class type.
+        model_kwargs (dict): Arguments to init the model.
+        checkpoint (str): Checkpoint filepath.
+        dataset (:obj:`Dataset`): The dataset to be tested.
+        data_func (callable): The function that generates model inputs.
+        gpus (list[int]): GPU ids to be used.
+        workers_per_gpu (int): Number of processes on each GPU. It is possible
+            to run multiple workers on each GPU.
+
+    Returns:
+        list: Test results.
+    """
+    ctx = multiprocessing.get_context('spawn')
+    idx_queue = ctx.Queue()
+    result_queue = ctx.Queue()
+    num_workers = len(gpus) * workers_per_gpu
+    workers = [
+        ctx.Process(
+            target=worker_func,
+            args=(model_cls, model_kwargs, checkpoint, dataset, data_func,
+                  gpus[i % len(gpus)], idx_queue, result_queue))
+        for i in range(num_workers)
+    ]
+    for w in workers:
+        w.daemon = True
+        w.start()
+
+    for i in range(len(dataset)):
+        idx_queue.put(i)
+
+    results = [None for _ in range(len(dataset))]
+    import cvbase as cvb
+    prog_bar = cvb.ProgressBar(task_num=len(dataset))
+    for _ in range(len(dataset)):
+        idx, res = result_queue.get()
+        results[idx] = res
+        prog_bar.update()
+    print('\n')
+    for worker in workers:
+        worker.terminate()
+
+    return results

mmcv/torchpack/runner/__init__.py

@@ -0,0 +1,2 @@
+from .log_buffer import LogBuffer
+from .runner import Runner

mmcv/torchpack/runner/log_buffer.py

@@ -0,0 +1,39 @@
+from collections import OrderedDict
+import numpy as np
+
+
+class LogBuffer(object):
+
+    def __init__(self):
+        self.val_history = OrderedDict()
+        self.n_history = OrderedDict()
+        self.output = OrderedDict()
+        self.ready = False
+
+    def clear(self):
+        self.val_history.clear()
+        self.n_history.clear()
+        self.clear_output()
+
+    def clear_output(self):
+        self.output.clear()
+        self.ready = False
+
+    def update(self, vars, count=1):
+        assert isinstance(vars, dict)
+        for key, var in vars.items():
+            if key not in self.val_history:
+                self.val_history[key] = []
+                self.n_history[key] = []
+            self.val_history[key].append(var)
+            self.n_history[key].append(count)
+
+    def average(self, n=0):
+        """Average latest n values or all values"""
+        assert n >= 0
+        for key in self.val_history:
+            values = np.array(self.val_history[key][-n:])
+            nums = np.array(self.n_history[key][-n:])
+            avg = np.sum(values * nums) / np.sum(nums)
+            self.output[key] = avg
+        self.ready = True

mmcv/torchpack/runner/runner.py

@@ -0,0 +1,344 @@
+import logging
+import os.path as osp
+import time
+
+import mmcv
+import torch
+from torch.nn.parallel import DataParallel, DistributedDataParallel
+
+from .log_buffer import LogBuffer
+from .. import hooks
+from ..hooks import (Hook, LrUpdaterHook, CheckpointSaverHook, IterTimerHook,
+                     OptimizerStepperHook)
+from ..io import load_checkpoint, save_checkpoint
+from ..utils import (get_dist_info, get_host_info, get_time_str,
+                     add_file_handler, obj_from_dict)
+
+
+class Runner(object):
+    """A training helper for PyTorch."""
+
+    def __init__(self,
+                 model,
+                 optimizer,
+                 batch_processor,
+                 work_dir=None,
+                 log_level=logging.INFO):
+        assert callable(batch_processor)
+        self.model = model
+        self.optimizer = self.init_optimizer(optimizer)
+        self.batch_processor = batch_processor
+
+        # create work_dir
+        if mmcv.is_str(work_dir):
+            self.work_dir = osp.abspath(work_dir)
+            mmcv.mkdir_or_exist(self.work_dir)
+        elif work_dir is None:
+            self.work_dir = None
+        else:
+            raise TypeError('"work_dir" must be a str or None')
+
+        # get model name from the model class
+        if isinstance(self.model, (DataParallel, DistributedDataParallel)):
+            self._model_name = self.model.module.__class__.__name__
+        else:
+            self._model_name = self.model.__class__.__name__
+
+        self._rank, self._world_size = get_dist_info()
+        self.logger = self.init_logger(work_dir, log_level)
+        self.log_buffer = LogBuffer()
+
+        self.mode = None
+        self._hooks = []
+        self._epoch = 0
+        self._iter = 0
+        self._inner_iter = 0
+        self._max_epochs = 0
+        self._max_iters = 0
+
+    @property
+    def model_name(self):
+        """str: Name of the model, usually the module class name."""
+        return self._model_name
+
+    @property
+    def rank(self):
+        """int: Rank of current process. (distributed training)"""
+        return self._rank
+
+    @property
+    def world_size(self):
+        """int: Number of processes participating in the job.
+        (distributed training)"""
+        return self._world_size
+
+    @property
+    def hooks(self):
+        """list[:obj:`Hook`]: A list of registered hooks."""
+        return self._hooks
+
+    @property
+    def epoch(self):
+        """int: Current epoch."""
+        return self._epoch
+
+    @property
+    def iter(self):
+        """int: Current iteration."""
+        return self._iter
+
+    @property
+    def inner_iter(self):
+        """int: Iteration in an epoch."""
+        return self._inner_iter
+
+    @property
+    def max_epochs(self):
+        """int: Maximum training epochs."""
+        return self._max_epochs
+
+    @property
+    def max_iters(self):
+        """int: Maximum training iterations."""
+        return self._max_iters
+
+    def init_optimizer(self, optimizer):
+        """Init the optimizer.
+
+        Args:
+            optimizer (dict or :obj:`~torch.optim.Optimizer`): Either an
+                optimizer object or a dict used for constructing the optimizer.
+                An example of the dict: ``{'algorithm': 'SGD', 'lr': 0.02,
+                'momentum': 0.9, 'weight_decay': 0.0001}``.
+
+        Returns:
+            :obj:`~torch.optim.Optimizer`: An optimizer object.
+        """
+        if isinstance(optimizer, dict):
+            optimizer = obj_from_dict(
+                optimizer, torch.optim, dict(params=self.model.parameters()))
+        elif not isinstance(optimizer, torch.optim.Optimizer):
+            raise TypeError(
+                'optimizer must be either an Optimizer object or a dict, '
+                'but got {}'.format(type(optimizer)))
+        return optimizer
+
+    def init_logger(self, log_dir=None, level=logging.INFO):
+        """Init the logger.
+
+        Args:
+            log_dir(str, optional): Log file directory. If not specified, no
+                log file will be used.
+            level (int or str): See the built-in python logging module.
+
+        Returns:
+            :obj:`~logging.Logger`: Python logger.
+        """
+        logging.basicConfig(
+            format='%(asctime)s - %(levelname)s - %(message)s', level=level)
+        logger = logging.getLogger(__name__)
+        if log_dir:
+            filename = '{}_{}.log'.format(get_time_str(), self.rank)
+            log_file = osp.join(log_dir, filename)
+            add_file_handler(logger, log_file, level=level)
+        return logger
+
+    def current_lr(self):
+        """Get current learning rates.
+
+        Returns:
+            list: Current learning rate of all param groups.
+        """
+        return [group['lr'] for group in self.optimizer.param_groups]
+
+    def register_hook(self, hook, priority=50):
+        """Register a hook into the hook list.
+
+        Args:
+            hook (:obj:`Hook`): The hook to be registered.
+            priority (int): Hook priority. Lower value means higher priority.
+        """
+        assert isinstance(hook, Hook)
+        assert isinstance(priority, int) and priority >= 0 and priority <= 100
+        if hasattr(hook, 'priority'):
+            raise ValueError('"priority" is a reserved attribute for hooks')
+        hook.priority = priority
+        # insert the hook to a sorted list
+        inserted = False
+        for i in range(len(self._hooks) - 1, -1, -1):
+            if priority >= self._hooks[i].priority:
+                self._hooks.insert(i + 1, hook)
+                inserted = True
+                break
+        if not inserted:
+            self._hooks.insert(0, hook)
+
+    def call_hook(self, fn_name):
+        for hook in self._hooks:
+            getattr(hook, fn_name)(self)
+
+    def load_checkpoint(self, filename, map_location='cpu', strict=False):
+        self.logger.info('load checkpoint from %s', filename)
+        return load_checkpoint(self.model, filename, map_location, strict,
+                               self.logger)
+
+    def save_checkpoint(self,
+                        out_dir,
+                        filename_tmpl='epoch_{}.pth',
+                        save_optimizer=True,
+                        meta=None):
+        if meta is None:
+            meta = dict(epoch=self.epoch + 1, iter=self.iter)
+        else:
+            meta.update(epoch=self.epoch + 1, iter=self.iter)
+
+        filename = osp.join(out_dir, filename_tmpl.format(self.epoch))
+        linkname = osp.join(out_dir, 'latest.pth')
+        optimizer = self.optimizer if save_optimizer else None
+        save_checkpoint(self.model, filename, optimizer=optimizer, meta=meta)
+        mmcv.symlink(filename, linkname)
+
+    def train(self, data_loader, **kwargs):
+        self.model.train()
+        self.mode = 'train'
+        self.data_loader = data_loader
+        self._max_iters = self._max_epochs * len(data_loader)
+        self.call_hook('before_train_epoch')
+
+        for i, data_batch in enumerate(data_loader):
+            self._inner_iter = i
+            self.call_hook('before_train_iter')
+            outputs = self.batch_processor(
+                self.model, data_batch, train_mode=True, **kwargs)
+            if not isinstance(outputs, dict):
+                raise TypeError('batch_processor() must return a dict')
+            if 'log_vars' in outputs:
+                self.log_buffer.update(outputs['log_vars'],
+                                       outputs['num_samples'])
+            self.outputs = outputs
+            self.call_hook('after_train_iter')
+            self._iter += 1
+
+        self.call_hook('after_train_epoch')
+        self._epoch += 1
+
+    def val(self, data_loader, **kwargs):
+        self.model.eval()
+        self.mode = 'val'
+        self.data_loader = data_loader
+        self.call_hook('before_val_epoch')
+
+        for i, data_batch in enumerate(data_loader):
+            self._inner_iter = i
+            self.call_hook('before_val_iter')
+            outputs = self.batch_processor(
+                self.model, data_batch, train_mode=False, **kwargs)
+            if not isinstance(outputs, dict):
+                raise TypeError('batch_processor() must return a dict')
+            if 'log_vars' in outputs:
+                self.log_buffer.update(outputs['log_vars'],
+                                       outputs['num_samples'])
+            self.outputs = outputs
+            self.call_hook('after_val_iter')
+
+        self.call_hook('after_val_epoch')
+
+    def resume(self, checkpoint, resume_optimizer=True,
+               map_location='default'):
+        if map_location == 'default':
+            device_id = torch.cuda.current_device()
+            checkpoint = self.load_checkpoint(
+                checkpoint,
+                map_location=lambda storage, loc: storage.cuda(device_id))
+        else:
+            checkpoint = self.load_checkpoint(
+                checkpoint, map_location=map_location)
+
+        self._epoch = checkpoint['meta']['epoch']
+        self._iter = checkpoint['meta']['iter']
+        if 'optimizer' in checkpoint and resume_optimizer:
+            self.optimizer.load_state_dict(checkpoint['optimizer'])
+
+        self.logger.info('resumed epoch %d, iter %d', self.epoch, self.iter)
+
+    def run(self, data_loaders, workflow, max_epochs, **kwargs):
+        assert isinstance(data_loaders, list)
+        assert mmcv.is_list_of(workflow, tuple)
+        assert len(data_loaders) == len(workflow)
+
+        self._max_epochs = max_epochs
+        work_dir = self.work_dir if self.work_dir is not None else 'NONE'
+        self.logger.info('Start running, host: %s, work_dir: %s',
+                         get_host_info(), work_dir)
+        self.logger.info('workflow: %s, max: %d epochs', workflow, max_epochs)
+        self.call_hook('before_run')
+
+        while self.epoch < max_epochs:
+            for i, flow in enumerate(workflow):
+                mode, epochs = flow
+                if isinstance(mode, str):  # self.train()
+                    if not hasattr(self, mode):
+                        raise ValueError(
+                            'runner has no method named "{}" to run an epoch'.
+                            format(mode))
+                    epoch_runner = getattr(self, mode)
+                elif callable(mode):  # custom train()
+                    epoch_runner = mode
+                else:
+                    raise TypeError('mode in workflow must be a str or '
+                                    'callable function, not {}'.format(
+                                        type(mode)))
+                for _ in range(epochs):
+                    if mode == 'train' and self.epoch >= max_epochs:
+                        return
+                    epoch_runner(data_loaders[i], **kwargs)
+
+        time.sleep(1)  # wait for some hooks like loggers to finish
+        self.call_hook('after_run')
+
+    def register_lr_hooks(self, lr_config):
+        if isinstance(lr_config, LrUpdaterHook):
+            self.register_hook(lr_config)
+        elif isinstance(lr_config, dict):
+            assert 'policy' in lr_config
+            from ..hooks import lr_updater
+            hook_name = lr_config['policy'].title() + 'LrUpdaterHook'
+            if not hasattr(lr_updater, hook_name):
+                raise ValueError('"{}" does not exist'.format(hook_name))
+            hook_cls = getattr(lr_updater, hook_name)
+            self.register_hook(hook_cls(**lr_config))
+        else:
+            raise TypeError('"lr_config" must be either a LrUpdaterHook object'
+                            ' or dict, not {}'.format(type(lr_config)))
+
+    def register_logger_hooks(self, log_config):
+        log_interval = log_config['interval']
+        for info in log_config['hooks']:
+            logger_hook = obj_from_dict(
+                info, hooks, default_args=dict(interval=log_interval))
+            self.register_hook(logger_hook, priority=60)
+
+    def register_default_hooks(self,
+                               lr_config,
+                               grad_clip_config=None,
+                               checkpoint_config=None,
+                               log_config=None):
+        """Register several default hooks.
+
+        Default hooks include:
+        - LrUpdaterHook
+        - OptimizerStepperHook
+        - CheckpointSaverHook
+        - IterTimerHook
+        - LoggerHook
+        """
+        if grad_clip_config is None:
+            grad_clip_config = {}
+        if checkpoint_config is None:
+            checkpoint_config = {}
+        self.register_lr_hooks(lr_config)
+        self.register_hook(OptimizerStepperHook(**grad_clip_config))
+        self.register_hook(CheckpointSaverHook(**checkpoint_config))
+        self.register_hook(IterTimerHook())
+        if log_config is not None:
+            self.register_logger_hooks(log_config)

mmcv/torchpack/utils.py

@@ -0,0 +1,77 @@
+import functools
+import logging
+import time
+from getpass import getuser
+from socket import gethostname
+
+import mmcv
+import torch.distributed as dist
+
+
+def get_host_info():
+    return '{}@{}'.format(getuser(), gethostname())
+
+
+def get_dist_info():
+    if dist._initialized:
+        rank = dist.get_rank()
+        world_size = dist.get_world_size()
+    else:
+        rank = 0
+        world_size = 1
+    return rank, world_size
+
+
+def master_only(func):
+
+    @functools.wraps(func)
+    def wrapper(*args, **kwargs):
+        rank, _ = get_dist_info()
+        if rank == 0:
+            return func(*args, **kwargs)
+
+    return wrapper
+
+
+def get_time_str():
+    return time.strftime('%Y%m%d_%H%M%S', time.localtime())
+
+
+def add_file_handler(logger, filename=None, mode='w', level=logging.INFO):
+    file_handler = logging.FileHandler(filename, mode)
+    file_handler.setFormatter(
+        logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
+    logger.addHandler(file_handler)
+    return logger
+
+
+def obj_from_dict(info, module, default_args=None):
+    """Initialize an object from dict.
+
+    The dict must contain the key "type", which indicates the object type, it
+    can be either a string or type, such as "list" or ``list``. Remaining
+    fields are treated as the arguments for constructing the object.
+
+    Args:
+        info (dict): Object types and arguments.
+        module (:class:`module`): Module which may containing expected object
+            classes.
+        default_args (dict, optional): Default arguments for initializing the
+            object.
+
+    Returns:
+
+    """
+    assert isinstance(info, dict) and 'type' in info
+    assert isinstance(default_args, dict) or default_args is None
+    args = info.copy()
+    obj_type = args.pop('type')
+    if mmcv.is_str(obj_type):
+        obj_type = getattr(module, obj_type)
+    elif not isinstance(obj_type, type):
+        raise TypeError('type must be a str or valid type, but got {}'.format(
+            type(obj_type)))
+    if default_args is not None:
+        for name, value in default_args.items():
+            args.setdefault(name, value)
+    return obj_type(**args)