How to use the fvcore.common.timer.Timer function in fvcore

def test_timer(self):
        timer = Timer()
        time.sleep(0.5)
        self.assertTrue(0.99 > timer.seconds() >= 0.5)

        timer.pause()
        time.sleep(0.5)

        self.assertTrue(0.99 > timer.seconds() >= 0.5)

        timer.resume()
        time.sleep(0.5)
        self.assertTrue(1.49 > timer.seconds() >= 1.0)

        timer.reset()
        self.assertTrue(0.49 > timer.seconds() >= 0)

def benchmark_data(args):
    cfg = setup(args)

    dataloader = build_detection_train_loader(cfg)

    timer = Timer()
    itr = iter(dataloader)
    for i in range(10):  # warmup
        next(itr)
        if i == 0:
            startup_time = timer.seconds()
    timer = Timer()
    max_iter = 1000
    for _ in tqdm.trange(max_iter):
        next(itr)
    logger.info(
        "{} iters ({} images) in {} seconds.".format(
            max_iter, max_iter * cfg.SOLVER.IMS_PER_BATCH, timer.seconds()
        )
    )
    logger.info("Startup time: {} seconds".format(startup_time))
    vram = psutil.virtual_memory()

def __init__(self, warmup_iter=3):
        """
        Args:
            warmup_iter (int): the number of iterations at the beginning to exclude
                from timing.
        """
        self._warmup_iter = warmup_iter
        self._step_timer = Timer()

extra_annotation_keys (list[str]): list of per-annotation keys that should also be
            loaded into the dataset dict (besides "iscrowd", "bbox", "keypoints",
            "category_id", "segmentation"). The values for these keys will be returned as-is.
            For example, the densepose annotations are loaded in this way.

    Returns:
        list[dict]: a list of dicts in Detectron2 standard format. (See
        `Using Custom Datasets `_ )

    Notes:
        1. This function does not read the image files.
           The results do not have the "image" field.
    """
    from pycocotools.coco import COCO

    timer = Timer()
    json_file = PathManager.get_local_path(json_file)
    with contextlib.redirect_stdout(io.StringIO()):
        coco_api = COCO(json_file)
    if timer.seconds() > 1:
        logger.info("Loading {} takes {:.2f} seconds.".format(json_file, timer.seconds()))

    id_map = None
    if dataset_name is not None:
        meta = MetadataCatalog.get(dataset_name)
        cat_ids = sorted(coco_api.getCatIds())
        cats = coco_api.loadCats(cat_ids)
        # The categories in a custom json file may not be sorted.
        thing_classes = [c["name"] for c in sorted(cats, key=lambda x: x["id"])]
        meta.thing_classes = thing_classes

        # In COCO, certain category ids are artificially removed,

If provided, this function will put "thing_classes" into the metadata
            associated with this dataset.

    Returns:
        list[dict]: a list of dicts in Detectron2 standard format. (See
        `Using Custom Datasets `_ )

    Notes:
        1. This function does not read the image files.
           The results do not have the "image" field.
    """
    from lvis import LVIS

    json_file = PathManager.get_local_path(json_file)

    timer = Timer()
    lvis_api = LVIS(json_file)
    if timer.seconds() > 1:
        logger.info("Loading {} takes {:.2f} seconds.".format(json_file, timer.seconds()))

    if dataset_name is not None:
        meta = get_lvis_instances_meta(dataset_name)
        MetadataCatalog.get(dataset_name).set(**meta)

    # sort indices for reproducible results
    img_ids = sorted(list(lvis_api.imgs.keys()))
    # imgs is a list of dicts, each looks something like:
    # {'license': 4,
    #  'url': 'http://farm6.staticflickr.com/5454/9413846304_881d5e5c3b_z.jpg',
    #  'file_name': 'COCO_val2014_000000001268.jpg',
    #  'height': 427,
    #  'width': 640,

def before_train(self):
        self._start_time = time.perf_counter()
        self._total_timer = Timer()
        self._total_timer.pause()

DetectionCheckpointer(model).load(cfg.MODEL.WEIGHTS)

    cfg.defrost()
    cfg.DATALOADER.NUM_WORKERS = 0
    data_loader = build_detection_test_loader(cfg, cfg.DATASETS.TEST[0])
    dummy_data = list(itertools.islice(data_loader, 100))

    def f():
        while True:
            yield from DatasetFromList(dummy_data, copy=False)

    for _ in range(5):  # warmup
        model(dummy_data[0])

    max_iter = 400
    timer = Timer()
    with tqdm.tqdm(total=max_iter) as pbar:
        for idx, d in enumerate(f()):
            if idx == max_iter:
                break
            model(d)
            pbar.update()
    logger.info("{} iters in {} seconds.".format(max_iter, timer.seconds()))