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| # Copyright (c) Facebook, Inc. and its affiliates. | |
| import datetime | |
| import logging | |
| import time | |
| from collections import OrderedDict | |
| from contextlib import ExitStack, contextmanager | |
| 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): | |
| """ | |
| 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 (DatasetEvaluator): the evaluator to run. Use `None` if you only want | |
| to benchmark, but don't want to do any evaluation. | |
| Returns: | |
| The return value of `evaluator.evaluate()` | |
| """ | |
| num_devices = get_world_size() | |
| logger = logging.getLogger(__name__) | |
| logger.info("Start inference on {} images".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([]) | |
| evaluator.reset() | |
| num_warmup = min(5, total - 1) | |
| start_time = time.perf_counter() | |
| total_compute_time = 0 | |
| with ExitStack() as stack: | |
| if isinstance(model, nn.Module): | |
| stack.enter_context(inference_context(model)) | |
| stack.enter_context(torch.no_grad()) | |
| for idx, inputs in enumerate(data_loader): | |
| if idx == num_warmup: | |
| start_time = time.perf_counter() | |
| total_compute_time = 0 | |
| start_compute_time = time.perf_counter() | |
| outputs = model(inputs) | |
| if torch.cuda.is_available(): | |
| torch.cuda.synchronize() | |
| total_compute_time += time.perf_counter() - start_compute_time | |
| evaluator.process(inputs, outputs) | |
| iters_after_start = idx + 1 - num_warmup * int(idx >= num_warmup) | |
| seconds_per_img = total_compute_time / iters_after_start | |
| if idx >= num_warmup * 2 or seconds_per_img > 5: | |
| total_seconds_per_img = (time.perf_counter() - start_time) / iters_after_start | |
| eta = datetime.timedelta(seconds=int(total_seconds_per_img * (total - idx - 1))) | |
| log_every_n_seconds( | |
| logging.INFO, | |
| "Inference done {}/{}. {:.4f} s / img. ETA={}".format( | |
| idx + 1, total, seconds_per_img, str(eta) | |
| ), | |
| n=5, | |
| ) | |
| # 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 / img 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 / img 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) | |