Force consistent it/s display in TQDM progress bar

[awaelchli]

What does this PR do?

When the average iteration time is larger than a second, the progress bar switches from it/s to the reciprocal s/it. This can be confusing if the user is used to seeing it/s and doesn't pay attention. This PR proposes to force the display to always be it/s even if the rate drops below 1. We can achieve this by setting the bar_format argument and modifying the default formatting style to include the rate_noinv_fmt instead of the rate_fmt.

Before:

Epoch 0:   0%|          | 2/50000 [00:06<42:10:29,  3.04s/it, v_num=78]

Now:

Epoch 0:   0%|          | 3/50000 [00:09<42:03:08,  0.33it/s, v_num=77]

Code example for repro:

import time

import torch
from torch.utils.data import DataLoader, Dataset

from lightning.pytorch import LightningModule, Trainer


class RandomDataset(Dataset):
    def __init__(self, size, length):
        self.len = length
        self.data = torch.randn(length, size)

    def __getitem__(self, index):
        return self.data[index]

    def __len__(self):
        return self.len


class BoringModel(LightningModule):
    def __init__(self):
        super().__init__()
        self.layer = torch.nn.Linear(32, 2)

    def training_step(self, batch, batch_idx):
        time.sleep(3)
        return self.layer(batch).sum()

    def configure_optimizers(self):
        return torch.optim.SGD(self.layer.parameters(), lr=0.1)


train_data = DataLoader(RandomDataset(32, 100000), batch_size=2, num_workers=0)
model = BoringModel()
trainer = Trainer()
trainer.fit(model, train_data)

---

📚 Documentation preview 📚: https://pytorch-lightning--18593.org.readthedocs.build/en/18593/

cc @Borda @awaelchli

[github-actions]

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🟢 pytorch_lightning: Tests workflow

Check ID	Status
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pl-cpu (macOS-11, lightning, 3.9, 1.12)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 1.13)	success	✅
pl-cpu (macOS-11, lightning, 3.10, 2.0)	success	✅
pl-cpu (macOS-11, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.11)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.9, 1.12)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 1.13)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.10, 2.0)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.11)	success	✅
pl-cpu (windows-2022, lightning, 3.9, 1.12)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 1.13)	success	✅
pl-cpu (windows-2022, lightning, 3.10, 2.0)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.11, oldest)	success	✅
pl-cpu (macOS-11, pytorch, 3.8, 1.13)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.8, 1.13)	success	✅
pl-cpu (windows-2022, pytorch, 3.8, 1.13)	success	✅
pl-cpu (macOS-12, pytorch, 3.11, 2.0)	success	✅
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pl-cpu (windows-2022, pytorch, 3.11, 2.0)	success	✅

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docs-make (pytorch, html)	success	✅

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🟢 install

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install-pkg (ubuntu-22.04, app, 3.8)	success	✅
install-pkg (ubuntu-22.04, app, 3.11)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.8)	success	✅
install-pkg (ubuntu-22.04, fabric, 3.11)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.8)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.11)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.8)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.11)	success	✅
install-pkg (ubuntu-22.04, notset, 3.8)	success	✅
install-pkg (ubuntu-22.04, notset, 3.11)	success	✅
install-pkg (macOS-12, app, 3.8)	success	✅
install-pkg (macOS-12, app, 3.11)	success	✅
install-pkg (macOS-12, fabric, 3.8)	success	✅
install-pkg (macOS-12, fabric, 3.11)	success	✅
install-pkg (macOS-12, pytorch, 3.8)	success	✅
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install-pkg (macOS-12, lightning, 3.11)	success	✅
install-pkg (macOS-12, notset, 3.8)	success	✅
install-pkg (macOS-12, notset, 3.11)	success	✅
install-pkg (windows-2022, app, 3.8)	success	✅
install-pkg (windows-2022, app, 3.11)	success	✅
install-pkg (windows-2022, fabric, 3.8)	success	✅
install-pkg (windows-2022, fabric, 3.11)	success	✅
install-pkg (windows-2022, pytorch, 3.8)	success	✅
install-pkg (windows-2022, pytorch, 3.11)	success	✅
install-pkg (windows-2022, lightning, 3.8)	success	✅
install-pkg (windows-2022, lightning, 3.11)	success	✅
install-pkg (windows-2022, notset, 3.8)	success	✅
install-pkg (windows-2022, notset, 3.11)	success	✅

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---

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[codecov]

Codecov Report

Merging #18593 (24bedc5) into master (32415c6) will decrease coverage by 34%.
Report is 1 commits behind head on master.
The diff coverage is 100%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #18593      +/-   ##
==========================================
- Coverage      85%      50%     -34%     
==========================================
  Files         427      419       -8     
  Lines       33367    33222     -145     
==========================================
- Hits        28281    16744   -11537     
- Misses       5086    16478   +11392