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FlexibleRunner

class mmengine.runner.FlexibleRunner(model, *, work_dir='work_dirs', experiment_name=None, train_dataloader=None, optim_wrapper=None, param_scheduler=None, train_cfg=None, val_dataloader=None, val_evaluator=None, val_cfg=None, test_dataloader=None, test_evaluator=None, test_cfg=None, strategy=None, auto_scale_lr=None, default_hooks=None, custom_hooks=None, data_preprocessor=None, load_from=None, resume=False, launcher=None, env_cfg={'dist_cfg': {'backend': 'nccl'}}, log_processor=None, log_level='INFO', visualizer=None, default_scope='mmengine', randomness={'seed': None}, compile=False, cfg=None)[source]

A training helper for PyTorch.

Runner object can be built from config by runner = Runner.from_cfg(cfg) where the cfg usually contains training, validation, and test-related configurations to build corresponding components. We usually use the same config to launch training, testing, and validation tasks. However, only some of these components are necessary at the same time, e.g., testing a model does not need training or validation-related components.

To avoid repeatedly modifying config, the construction of Runner adopts lazy initialization to only initialize components when they are going to be used. Therefore, the model is always initialized at the beginning, and training, validation, and, testing related components are only initialized when calling runner.train(), runner.val(), and runner.test(), respectively.

Warning

This is an experimental feature, and its interface is subject to change.

Parameters
Kwargs:
work_dir (str, optional): The working directory to save checkpoints.

The logs will be saved in the subdirectory of work_dir named timestamp. Defaults to ‘work_dir’.

experiment_name (str, optional): Name of current experiment. If not

specified, timestamp will be used as experiment_name. Defaults to None.

train_dataloader (Dataloader or dict, optional): A dataloader object or

a dict to build a dataloader. If None is given, it means skipping training steps. Defaults to None. See build_dataloader() for more details.

optim_wrapper (OptimWrapper or dict, optional):

Computing gradient of model parameters. If specified, train_dataloader should also be specified. If automatic mixed precision or gradient accmulation training is required. The type of optim_wrapper should be AmpOptimizerWrapper. See build_optim_wrapper() for examples. Defaults to None.

param_scheduler (_ParamScheduler or dict or list, optional):

Parameter scheduler for updating optimizer parameters. If specified, optimizer should also be specified. Defaults to None. See build_param_scheduler() for examples.

train_cfg (dict, optional): A dict to build a training loop. If it does

not provide “type” key, it should contain “by_epoch” to decide which type of training loop EpochBasedTrainLoop or IterBasedTrainLoop should be used. If train_cfg specified, train_dataloader should also be specified. Defaults to None. See build_train_loop() for more details.

val_dataloader (Dataloader or dict, optional): A dataloader object or

a dict to build a dataloader. If None is given, it means skipping validation steps. Defaults to None. See build_dataloader() for more details.

val_evaluator (Evaluator or dict or list, optional): A evaluator object

used for computing metrics for validation. It can be a dict or a list of dict to build a evaluator. If specified, val_dataloader should also be specified. Defaults to None.

val_cfg (dict, optional): A dict to build a validation loop. If it does

not provide “type” key, ValLoop will be used by default. If val_cfg specified, val_dataloader should also be specified. If ValLoop is built with fp16=True`, runner.val() will be performed under fp16 precision.

test_dataloader (Dataloader or dict, optional): A dataloader object or

a dict to build a dataloader. If None is given, it means skipping test steps. Defaults to None. See build_dataloader() for more details. Defaults to None. See build_val_loop() for more details.

test_evaluator (Evaluator or dict or list, optional): A evaluator

object used for computing metrics for test steps. It can be a dict or a list of dict to build a evaluator. If specified, test_dataloader should also be specified. Defaults to None.

test_cfg (dict, optional): A dict to build a test loop. If it does

not provide “type” key, TestLoop will be used by default. If test_cfg specified, test_dataloader should also be specified. If ValLoop is built with fp16=True`, runner.val() will be performed under fp16 precision. Defaults to None. See build_test_loop() for more details.

strategy (BaseStrategy or dict, optional): A strategy object or a dict

to build a strategy. Defaults to None. If not specified, the strategy will be inferred automatically.

auto_scale_lr (dict, Optional): Config to scale the learning rate

automatically. It includes base_batch_size and enable. base_batch_size is the batch size that the optimizer lr is based on. enable is the switch to turn on and off the feature.

default_hooks (dict[str, dict] or dict[str, Hook], optional): Hooks to

execute default actions like updating model parameters and saving checkpoints. Default hooks are OptimizerHook, IterTimerHook, LoggerHook, ParamSchedulerHook and CheckpointHook. Defaults to None. See register_default_hooks() for more details.

custom_hooks (list[dict] or list[Hook], optional): Hooks to execute

custom actions like visualizing images processed by pipeline. Defaults to None.

data_preprocessor (dict, optional): The pre-process config of

BaseDataPreprocessor. If the model argument is a dict and doesn’t contain the key data_preprocessor, set the argument as the data_preprocessor of the model dict. Defaults to None.

load_from (str, optional): The checkpoint file to load from.

Defaults to None.

resume (bool): Whether to resume training. Defaults to False. If

resume is True and load_from is None, automatically to find latest checkpoint from work_dir. If not found, resuming does nothing.

launcher (str, optional): Way to launcher multi-process. Supported

launchers are ‘pytorch’, ‘mpi’, ‘slurm’ and ‘none’. If ‘none’ is provided, non-distributed environment will be launched. If launcher is None, the launcher will be inferred according some specified environments. Defaults to None.

env_cfg (dict): A dict used for setting environment. Defaults to

dict(dist_cfg=dict(backend=’nccl’)).

log_processor (dict, optional): A processor to format logs. Defaults to

None.

log_level (int or str): The log level of MMLogger handlers.

Defaults to ‘INFO’.

visualizer (Visualizer or dict, optional): A Visualizer object or a

dict build Visualizer object. Defaults to None. If not specified, default config will be used.

default_scope (str): Used to reset registries location.

Defaults to “mmengine”.

randomness (dict): Some settings to make the experiment as reproducible

as possible like seed and deterministic. Defaults to dict(seed=None). If seed is None, a random number will be generated and it will be broadcasted to all other processes if in distributed environment. If cudnn_benchmark is True in env_cfg but deterministic is True in randomness, the value of torch.backends.cudnn.benchmark will be False finally.

compile (bool or dict, optional): Whether to enable torch.compile.

Defaults to False.

cfg (dict or Configdict or Config, optional): Full config.

Defaults to None.

Note

Since PyTorch 2.0.0, you can enable torch.compile by passing in compile = True. If you want to control compile options, you can pass a dict, e.g. cfg.compile = dict(backend='eager'). Refer to PyTorch API Documentation for more valid options.

Examples

>>> from mmengine.runner import Runner
>>> cfg = dict(
>>>     model=dict(type='ToyModel'),
>>>     work_dir='path/of/work_dir',
>>>     train_dataloader=dict(
>>>     dataset=dict(type='ToyDataset'),
>>>     sampler=dict(type='DefaultSampler', shuffle=True),
>>>     batch_size=1,
>>>     num_workers=0),
>>>     val_dataloader=dict(
>>>         dataset=dict(type='ToyDataset'),
>>>         sampler=dict(type='DefaultSampler', shuffle=False),
>>>        batch_size=1,
>>>        num_workers=0),
>>>     test_dataloader=dict(
>>>         dataset=dict(type='ToyDataset'),
>>>         sampler=dict(type='DefaultSampler', shuffle=False),
>>>         batch_size=1,
>>>         num_workers=0),
>>>     auto_scale_lr=dict(base_batch_size=16, enable=False),
>>>     optim_wrapper=dict(type='OptimizerWrapper', optimizer=dict(
>>>         type='SGD', lr=0.01)),
>>>     param_scheduler=dict(type='MultiStepLR', milestones=[1, 2]),
>>>     val_evaluator=dict(type='ToyEvaluator'),
>>>     test_evaluator=dict(type='ToyEvaluator'),
>>>     train_cfg=dict(by_epoch=True, max_epochs=3, val_interval=1),
>>>     val_cfg=dict(),
>>>     test_cfg=dict(),
>>>     custom_hooks=[],
>>>     default_hooks=dict(
>>>         timer=dict(type='IterTimerHook'),
>>>         checkpoint=dict(type='CheckpointHook', interval=1),
>>>         logger=dict(type='LoggerHook'),
>>>         optimizer=dict(type='OptimizerHook', grad_clip=False),
>>>         param_scheduler=dict(type='ParamSchedulerHook')),
>>>     launcher='none',
>>>     env_cfg=dict(dist_cfg=dict(backend='nccl')),
>>>     log_processor=dict(window_size=20),
>>>     visualizer=dict(type='Visualizer',
>>>     vis_backends=[dict(type='LocalVisBackend',
>>>                        save_dir='temp_dir')])
>>>    )
>>> runner = Runner.from_cfg(cfg)
>>> runner.train()
>>> runner.test()
static build_dataloader(dataloader, seed=None, diff_rank_seed=False)[source]

Build dataloader.

The method builds three components:

  • Dataset

  • Sampler

  • Dataloader

An example of dataloader:

dataloader = dict(
    dataset=dict(type='ToyDataset'),
    sampler=dict(type='DefaultSampler', shuffle=True),
    batch_size=1,
    num_workers=9
)
Parameters
  • dataloader (DataLoader or dict) – A Dataloader object or a dict to build Dataloader object. If dataloader is a Dataloader object, just returns itself.

  • seed (int, optional) – Random seed. Defaults to None.

  • diff_rank_seed (bool) – Whether or not set different seeds to different ranks. If True, the seed passed to sampler is set to None, in order to synchronize the seeds used in samplers across different ranks. Defaults to False.

Returns

DataLoader build from dataloader_cfg.

Return type

Dataloader

build_evaluator(evaluator)[source]

Build evaluator.

Examples of evaluator:

# evaluator could be a built Evaluator instance
evaluator = Evaluator(metrics=[ToyMetric()])

# evaluator can also be a list of dict
evaluator = [
    dict(type='ToyMetric1'),
    dict(type='ToyEvaluator2')
]

# evaluator can also be a list of built metric
evaluator = [ToyMetric1(), ToyMetric2()]

# evaluator can also be a dict with key metrics
evaluator = dict(metrics=ToyMetric())
# metric is a list
evaluator = dict(metrics=[ToyMetric()])
Parameters

evaluator (Evaluator or dict or list) – An Evaluator object or a config dict or list of config dict used to build an Evaluator.

Returns

Evaluator build from evaluator.

Return type

Evaluator

build_log_processor(log_processor)[source]

Build test log_processor.

Examples of log_processor:

# LogProcessor will be used log_processor = dict()

# custom log_processor log_processor = dict(type=’CustomLogProcessor’)

Parameters
  • log_processor (LogProcessor or dict) – A log processor or a dict

  • processor (to build log processor. If log_processor is a log) –

  • object

  • itself. (just returns) –

Returns

Log processor object build from log_processor_cfg.

Return type

LogProcessor

build_message_hub(message_hub=None)[source]

Build a global asscessable MessageHub.

Parameters

message_hub (dict, optional) – A dict to build MessageHub object. If not specified, default config will be used to build MessageHub object. Defaults to None.

Returns

A MessageHub object build from message_hub.

Return type

MessageHub

build_strategy(strategy=None, launcher='none', randomness=None, env_cfg={'dist_cfg': {'backend': 'nccl'}}, experiment_name=None, log_level=None)[source]

Build a strategy.

Parameters
Returns

A strategy object.

Return type

BaseStrategy

build_test_loop(loop)[source]

Build test loop.

Examples of loop:

# `TestLoop` will be used
loop = dict()

# custom test loop
loop = dict(type='CustomTestLoop')
Parameters

loop (BaseLoop or dict) – A test loop or a dict to build test loop. If loop is a test loop object, just returns itself.

Returns

Test loop object build from loop_cfg.

Return type

BaseLoop

build_train_loop(loop)[source]

Build training loop.

Examples of loop:

# `EpochBasedTrainLoop` will be used
loop = dict(by_epoch=True, max_epochs=3)

# `IterBasedTrainLoop` will be used
loop = dict(by_epoch=False, max_epochs=3)

# custom training loop
loop = dict(type='CustomTrainLoop', max_epochs=3)
Parameters

loop (BaseLoop or dict) – A training loop or a dict to build training loop. If loop is a training loop object, just returns itself.

Returns

Training loop object build from loop.

Return type

BaseLoop

build_val_loop(loop)[source]

Build validation loop.

Examples of loop:

# ValLoop will be used loop = dict()

# custom validation loop loop = dict(type=’CustomValLoop’)

Parameters

loop (BaseLoop or dict) – A validation loop or a dict to build validation loop. If loop is a validation loop object, just returns itself.

Returns

Validation loop object build from loop.

Return type

BaseLoop

build_visualizer(visualizer=None)[source]

Build a global asscessable Visualizer.

Parameters

visualizer (Visualizer or dict, optional) – A Visualizer object or a dict to build Visualizer object. If visualizer is a Visualizer object, just returns itself. If not specified, default config will be used to build Visualizer object. Defaults to None.

Returns

A Visualizer object build from visualizer.

Return type

Visualizer

call_hook(fn_name, **kwargs)[source]

Call all hooks.

Parameters
  • fn_name (str) – The function name in each hook to be called, such as “before_train_epoch”.

  • **kwargs – Keyword arguments passed to hook.

Return type

None

property deterministic

Whether cudnn to select deterministic algorithms.

Type

int

property distributed

Whether current environment is distributed.

Type

bool

dump_config()[source]

Dump config to work_dir.

Return type

None

property epoch

Current epoch.

Type

int

property experiment_name

Name of experiment.

Type

str

classmethod from_cfg(cfg)[source]

Build a runner from config.

Parameters

cfg (ConfigType) – A config used for building runner. Keys of cfg can see __init__().

Returns

A runner build from cfg.

Return type

Runner

property hooks

A list of registered hooks.

Type

list[Hook]

property iter

Current iteration.

Type

int

load_checkpoint(filename, map_location='cpu', strict=False, revise_keys=[('^module.', '')])[source]

Load checkpoint from given filename.

Parameters
  • filename (str) – Accept local filepath, URL, torchvision://xxx, open-mmlab://xxx.

  • map_location (str or callable) – A string or a callable function to specifying how to remap storage locations. Defaults to ‘cpu’.

  • strict (bool) – strict (bool): Whether to allow different params for the model and checkpoint.

  • revise_keys (list) – A list of customized keywords to modify the state_dict in checkpoint. Each item is a (pattern, replacement) pair of the regular expression operations. Defaults to strip the prefix ‘module.’ by [(r’^module.’, ‘’)].

load_or_resume()[source]

load or resume checkpoint.

property max_epochs

Total epochs to train model.

Type

int

property max_iters

Total iterations to train model.

Type

int

property model_name

Name of the model, usually the module class name.

Type

str

property rank

Rank of current process.

Type

int

register_custom_hooks(hooks)[source]

Register custom hooks into hook list.

Parameters

hooks (list[Hook | dict]) – List of hooks or configs to be registered.

Return type

None

register_default_hooks(hooks=None)[source]

Register default hooks into hook list.

hooks will be registered into runner to execute some default actions like updating model parameters or saving checkpoints.

Default hooks and their priorities:

Hooks

Priority

RuntimeInfoHook

VERY_HIGH (10)

IterTimerHook

NORMAL (50)

DistSamplerSeedHook

NORMAL (50)

LoggerHook

BELOW_NORMAL (60)

ParamSchedulerHook

LOW (70)

CheckpointHook

VERY_LOW (90)

If hooks is None, above hooks will be registered by default:

default_hooks = dict(
    runtime_info=dict(type='RuntimeInfoHook'),
    timer=dict(type='IterTimerHook'),
    sampler_seed=dict(type='DistSamplerSeedHook'),
    logger=dict(type='LoggerHook'),
    param_scheduler=dict(type='ParamSchedulerHook'),
    checkpoint=dict(type='CheckpointHook', interval=1),
)

If not None, hooks will be merged into default_hooks. If there are None value in default_hooks, the corresponding item will be popped from default_hooks:

hooks = dict(timer=None)

The final registered default hooks will be RuntimeInfoHook, DistSamplerSeedHook, LoggerHook, ParamSchedulerHook and CheckpointHook.

Parameters

hooks (dict[str, Hook or dict], optional) – Default hooks or configs to be registered.

Return type

None

register_hook(hook, priority=None)[source]

Register a hook into the hook list.

The hook will be inserted into a priority queue, with the specified priority (See Priority for details of priorities). For hooks with the same priority, they will be triggered in the same order as they are registered.

Priority of hook will be decided with the following priority:

  • priority argument. If priority is given, it will be priority of hook.

  • If hook argument is a dict and priority in it, the priority will be the value of hook['priority'].

  • If hook argument is a dict but priority not in it or hook is an instance of hook, the priority will be hook.priority.

Parameters
  • hook (Hook or dict) – The hook to be registered.

  • priority (int or str or Priority, optional) – Hook priority. Lower value means higher priority.

Return type

None

register_hooks(default_hooks=None, custom_hooks=None)[source]

Register default hooks and custom hooks into hook list.

Parameters
  • default_hooks (dict[str, dict] or dict[str, Hook], optional) – Hooks to execute default actions like updating model parameters and saving checkpoints. Defaults to None.

  • custom_hooks (list[dict] or list[Hook], optional) – Hooks to execute custom actions like visualizing images processed by pipeline. Defaults to None.

Return type

None

resume(filename, resume_optimizer=True, resume_param_scheduler=True, map_location='default')[source]

Resume model from checkpoint.

Parameters
  • filename (str) – Accept local filepath, URL, torchvision://xxx, open-mmlab://xxx.

  • resume_optimizer (bool) – Whether to resume optimizer state. Defaults to True.

  • resume_param_scheduler (bool) – Whether to resume param scheduler state. Defaults to True.

  • map_location (str or callable) – A string or a callable function to specifying how to remap storage locations. Defaults to ‘default’.

Return type

None

save_checkpoint(out_dir, filename, file_client_args=None, save_optimizer=True, save_param_scheduler=True, meta=None, by_epoch=True, backend_args=None)[source]

Save checkpoints.

CheckpointHook invokes this method to save checkpoints periodically.

Parameters
  • out_dir (str) – The directory that checkpoints are saved.

  • filename (str) – The checkpoint filename.

  • file_client_args (dict, optional) – Arguments to instantiate a FileClient. See mmengine.fileio.FileClient for details. Defaults to None. It will be deprecated in future. Please use backend_args instead.

  • save_optimizer (bool) – Whether to save the optimizer to the checkpoint. Defaults to True.

  • save_param_scheduler (bool) – Whether to save the param_scheduler to the checkpoint. Defaults to True.

  • meta (dict, optional) – The meta information to be saved in the checkpoint. Defaults to None.

  • by_epoch (bool) – Whether the scheduled momentum is updated by epochs. Defaults to True.

  • backend_args (dict, optional) – Arguments to instantiate the prefix of uri corresponding backend. Defaults to None.

property seed

A number to set random modules.

Type

int

test()[source]

Launch test.

Returns

A dict of metrics on testing set.

Return type

dict

property test_dataloader

The data loader for testing.

property test_evaluator

An evaluator for testing.

Type

Evaluator

property test_loop

A loop to run testing.

Type

BaseLoop

property timestamp

Timestamp when creating experiment.

Type

str

train()[source]

Launch training.

Returns

The model after training.

Return type

nn.Module

property train_dataloader

The data loader for training.

property train_loop

A loop to run training.

Type

BaseLoop

val()[source]

Launch validation.

Returns

A dict of metrics on validation set.

Return type

dict

property val_begin

The epoch/iteration to start running validation during training.

Type

int

property val_dataloader

The data loader for validation.

property val_evaluator

An evaluator for validation.

Type

Evaluator

property val_interval

Interval to run validation during training.

Type

int

property val_loop

A loop to run validation.

Type

BaseLoop

property work_dir

The working directory to save checkpoints and logs.

Type

str

property world_size

Number of processes participating in the job.

Type

int

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