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# Copyright (c) Facebook, Inc. and its affiliates. | |
import datetime | |
import logging | |
import time | |
from collections import OrderedDict, abc | |
from contextlib import ExitStack, contextmanager | |
from typing import List, Union | |
import torch | |
from torch import nn | |
from detectron2.utils.comm import get_world_size, is_main_process | |
from detectron2.utils.logger import log_every_n_seconds | |
class DatasetEvaluator: | |
""" | |
Base class for a dataset evaluator. | |
The function :func:`inference_on_dataset` runs the model over | |
all samples in the dataset, and have a DatasetEvaluator to process the inputs/outputs. | |
This class will accumulate information of the inputs/outputs (by :meth:`process`), | |
and produce evaluation results in the end (by :meth:`evaluate`). | |
""" | |
def reset(self): | |
""" | |
Preparation for a new round of evaluation. | |
Should be called before starting a round of evaluation. | |
""" | |
pass | |
def process(self, inputs, outputs): | |
""" | |
Process the pair of inputs and outputs. | |
If they contain batches, the pairs can be consumed one-by-one using `zip`: | |
.. code-block:: python | |
for input_, output in zip(inputs, outputs): | |
# do evaluation on single input/output pair | |
... | |
Args: | |
inputs (list): the inputs that's used to call the model. | |
outputs (list): the return value of `model(inputs)` | |
""" | |
pass | |
def evaluate(self): | |
""" | |
Evaluate/summarize the performance, after processing all input/output pairs. | |
Returns: | |
dict: | |
A new evaluator class can return a dict of arbitrary format | |
as long as the user can process the results. | |
In our train_net.py, we expect the following format: | |
* key: the name of the task (e.g., bbox) | |
* value: a dict of {metric name: score}, e.g.: {"AP50": 80} | |
""" | |
pass | |
class DatasetEvaluators(DatasetEvaluator): | |
""" | |
Wrapper class to combine multiple :class:`DatasetEvaluator` instances. | |
This class dispatches every evaluation call to | |
all of its :class:`DatasetEvaluator`. | |
""" | |
def __init__(self, evaluators): | |
""" | |
Args: | |
evaluators (list): the evaluators to combine. | |
""" | |
super().__init__() | |
self._evaluators = evaluators | |
def reset(self): | |
for evaluator in self._evaluators: | |
evaluator.reset() | |
def process(self, inputs, outputs): | |
for evaluator in self._evaluators: | |
evaluator.process(inputs, outputs) | |
def evaluate(self): | |
results = OrderedDict() | |
for evaluator in self._evaluators: | |
result = evaluator.evaluate() | |
if is_main_process() and result is not None: | |
for k, v in result.items(): | |
assert ( | |
k not in results | |
), "Different evaluators produce results with the same key {}".format(k) | |
results[k] = v | |
return results | |
def inference_on_dataset( | |
model, | |
data_loader, | |
evaluator: Union[DatasetEvaluator, List[DatasetEvaluator], None], | |
callbacks=None, | |
): | |
""" | |
Run model on the data_loader and evaluate the metrics with evaluator. | |
Also benchmark the inference speed of `model.__call__` accurately. | |
The model will be used in eval mode. | |
Args: | |
model (callable): a callable which takes an object from | |
`data_loader` and returns some outputs. | |
If it's an nn.Module, it will be temporarily set to `eval` mode. | |
If you wish to evaluate a model in `training` mode instead, you can | |
wrap the given model and override its behavior of `.eval()` and `.train()`. | |
data_loader: an iterable object with a length. | |
The elements it generates will be the inputs to the model. | |
evaluator: the evaluator(s) to run. Use `None` if you only want to benchmark, | |
but don't want to do any evaluation. | |
callbacks (dict of callables): a dictionary of callback functions which can be | |
called at each stage of inference. | |
Returns: | |
The return value of `evaluator.evaluate()` | |
""" | |
num_devices = get_world_size() | |
logger = logging.getLogger(__name__) | |
logger.info("Start inference on {} batches".format(len(data_loader))) | |
total = len(data_loader) # inference data loader must have a fixed length | |
if evaluator is None: | |
# create a no-op evaluator | |
evaluator = DatasetEvaluators([]) | |
if isinstance(evaluator, abc.MutableSequence): | |
evaluator = DatasetEvaluators(evaluator) | |
evaluator.reset() | |
num_warmup = min(5, total - 1) | |
start_time = time.perf_counter() | |
total_data_time = 0 | |
total_compute_time = 0 | |
total_eval_time = 0 | |
with ExitStack() as stack: | |
if isinstance(model, nn.Module): | |
stack.enter_context(inference_context(model)) | |
stack.enter_context(torch.no_grad()) | |
start_data_time = time.perf_counter() | |
dict.get(callbacks or {}, "on_start", lambda: None)() | |
for idx, inputs in enumerate(data_loader): | |
total_data_time += time.perf_counter() - start_data_time | |
if idx == num_warmup: | |
start_time = time.perf_counter() | |
total_data_time = 0 | |
total_compute_time = 0 | |
total_eval_time = 0 | |
start_compute_time = time.perf_counter() | |
dict.get(callbacks or {}, "before_inference", lambda: None)() | |
outputs = model(inputs) | |
dict.get(callbacks or {}, "after_inference", lambda: None)() | |
if torch.cuda.is_available(): | |
torch.cuda.synchronize() | |
total_compute_time += time.perf_counter() - start_compute_time | |
start_eval_time = time.perf_counter() | |
evaluator.process(inputs, outputs) | |
total_eval_time += time.perf_counter() - start_eval_time | |
iters_after_start = idx + 1 - num_warmup * int(idx >= num_warmup) | |
data_seconds_per_iter = total_data_time / iters_after_start | |
compute_seconds_per_iter = total_compute_time / iters_after_start | |
eval_seconds_per_iter = total_eval_time / iters_after_start | |
total_seconds_per_iter = (time.perf_counter() - start_time) / iters_after_start | |
if idx >= num_warmup * 2 or compute_seconds_per_iter > 5: | |
eta = datetime.timedelta(seconds=int(total_seconds_per_iter * (total - idx - 1))) | |
log_every_n_seconds( | |
logging.INFO, | |
( | |
f"Inference done {idx + 1}/{total}. " | |
f"Dataloading: {data_seconds_per_iter:.4f} s/iter. " | |
f"Inference: {compute_seconds_per_iter:.4f} s/iter. " | |
f"Eval: {eval_seconds_per_iter:.4f} s/iter. " | |
f"Total: {total_seconds_per_iter:.4f} s/iter. " | |
f"ETA={eta}" | |
), | |
n=5, | |
) | |
start_data_time = time.perf_counter() | |
dict.get(callbacks or {}, "on_end", lambda: None)() | |
# Measure the time only for this worker (before the synchronization barrier) | |
total_time = time.perf_counter() - start_time | |
total_time_str = str(datetime.timedelta(seconds=total_time)) | |
# NOTE this format is parsed by grep | |
logger.info( | |
"Total inference time: {} ({:.6f} s / iter per device, on {} devices)".format( | |
total_time_str, total_time / (total - num_warmup), num_devices | |
) | |
) | |
total_compute_time_str = str(datetime.timedelta(seconds=int(total_compute_time))) | |
logger.info( | |
"Total inference pure compute time: {} ({:.6f} s / iter per device, on {} devices)".format( | |
total_compute_time_str, total_compute_time / (total - num_warmup), num_devices | |
) | |
) | |
results = evaluator.evaluate() | |
# An evaluator may return None when not in main process. | |
# Replace it by an empty dict instead to make it easier for downstream code to handle | |
if results is None: | |
results = {} | |
return results | |
def inference_context(model): | |
""" | |
A context where the model is temporarily changed to eval mode, | |
and restored to previous mode afterwards. | |
Args: | |
model: a torch Module | |
""" | |
training_mode = model.training | |
model.eval() | |
yield | |
model.train(training_mode) | |