Distributed sampling parity between Lite and PyTorch

[awaelchli]

What does this PR do?

Restores parity between pure PyTorch dataloader and Lite dataloader when using DistributedSampler (DDP).
This PR avoids the DistributedSamplerWrapper for the two standard samplers, RandomSampler and SequentialSampler. The DistributedSamplerWrapper should only be used for custom samplers. A note was added to the documentation of this wrapper.

We also ensure that .set_epoch() gets called automatically for the user.

Fixes #14636

Does your PR introduce any breaking changes? If yes, please list them.

The order of samples when shuffling is enabled. But this should be considered a bugfix.

Before submitting

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• Did you make sure to update the documentation with your changes? (if necessary)
• Did you write any new necessary tests? (not for typos and docs)
• Did you verify new and existing tests pass locally with your changes?
• Did you update the CHANGELOG? (not for typos, docs, test updates, or internal minor changes/refactorings)

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Did you have fun?

I made sure I had fun coding 🙃

cc @Borda @carmocca @justusschock @awaelchli

[github-actions]

⚡ Required checks status: All passing 🟢

Groups summary

🟢 pytorch_lightning: Tests workflow

Check ID	Status
pl-cpu (macOS-11, pytorch, 3.8, 1.11)	success	✅
pl-cpu (macOS-11, pytorch, 3.9, 1.12)	success	✅
pl-cpu (macOS-11, pytorch, 3.10, 1.13)	success	✅
pl-cpu (macOS-11, pytorch, 3.8, 1.10, oldest)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.8, 1.10)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.9, 1.11)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.10, 1.12)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.10, 1.13)	success	✅
pl-cpu (ubuntu-20.04, pytorch, 3.7, 1.10, oldest)	success	✅
pl-cpu (windows-2022, pytorch, 3.9, 1.11)	success	✅
pl-cpu (windows-2022, pytorch, 3.10, 1.12)	success	✅
pl-cpu (windows-2022, pytorch, 3.10, 1.13)	success	✅
pl-cpu (windows-2022, pytorch, 3.7, 1.10, oldest)	success	✅
pl-cpu (slow, macOS-11, pytorch, 3.7, 1.11)	success	✅
pl-cpu (slow, ubuntu-20.04, pytorch, 3.7, 1.11)	success	✅
pl-cpu (slow, windows-2022, pytorch, 3.7, 1.11)	success	✅
pl-cpu (macOS-11, lightning, 3.8, 1.13)	success	✅
pl-cpu (ubuntu-20.04, lightning, 3.8, 1.13)	success	✅
pl-cpu (windows-2022, lightning, 3.8, 1.13)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

🟢 pytorch_lightning: Azure GPU

Check ID	Status
pytorch-lightning (GPUs)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

🟢 pytorch_lightning: Azure HPU

Check ID	Status
pytorch-lightning (HPUs)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

🟢 pytorch_lightning: Azure IPU

Check ID	Status
pytorch-lightning (IPUs)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

🟢 lightning_lite: CPU workflow

Check ID	Status
lite-cpu (macOS-11, lite, 3.8, 1.11)	success	✅
lite-cpu (macOS-11, lite, 3.9, 1.12)	success	✅
lite-cpu (macOS-11, lite, 3.10, 1.13)	success	✅
lite-cpu (macOS-11, lite, 3.7, 1.10, oldest)	success	✅
lite-cpu (ubuntu-20.04, lite, 3.8, 1.10)	success	✅
lite-cpu (ubuntu-20.04, lite, 3.9, 1.11)	success	✅
lite-cpu (ubuntu-20.04, lite, 3.10, 1.12)	success	✅
lite-cpu (ubuntu-20.04, lite, 3.10, 1.13)	success	✅
lite-cpu (ubuntu-20.04, lite, 3.7, 1.10, oldest)	success	✅
lite-cpu (windows-2022, lite, 3.9, 1.11)	success	✅
lite-cpu (windows-2022, lite, 3.10, 1.12)	success	✅
lite-cpu (windows-2022, lite, 3.10, 1.13)	success	✅
lite-cpu (windows-2022, lite, 3.7, 1.10, oldest)	success	✅
lite-cpu (macOS-11, lightning, 3.8, 1.13)	success	✅
lite-cpu (ubuntu-20.04, lightning, 3.8, 1.13)	success	✅
lite-cpu (windows-2022, lightning, 3.8, 1.13)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py, tests/tests_lite/test_lite.py, tests/tests_lite/test_wrappers.py.

🟢 lightning_lite: Azure GPU

Check ID	Status
lightning-lite (GPUs)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py, tests/tests_lite/test_lite.py, tests/tests_lite/test_wrappers.py.

🟢 mypy

Check ID	Status
mypy	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

🟢 install

Check ID	Status
install-pkg (ubuntu-22.04, app, 3.7)	success	✅
install-pkg (ubuntu-22.04, app, 3.10)	success	✅
install-pkg (ubuntu-22.04, lite, 3.7)	success	✅
install-pkg (ubuntu-22.04, lite, 3.10)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.7)	success	✅
install-pkg (ubuntu-22.04, pytorch, 3.10)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.7)	success	✅
install-pkg (ubuntu-22.04, lightning, 3.10)	success	✅
install-pkg (ubuntu-22.04, notset, 3.7)	success	✅
install-pkg (ubuntu-22.04, notset, 3.10)	success	✅
install-pkg (macOS-12, app, 3.7)	success	✅
install-pkg (macOS-12, app, 3.10)	success	✅
install-pkg (macOS-12, lite, 3.7)	success	✅
install-pkg (macOS-12, lite, 3.10)	success	✅
install-pkg (macOS-12, pytorch, 3.7)	success	✅
install-pkg (macOS-12, pytorch, 3.10)	success	✅
install-pkg (macOS-12, lightning, 3.7)	success	✅
install-pkg (macOS-12, lightning, 3.10)	success	✅
install-pkg (macOS-12, notset, 3.7)	success	✅
install-pkg (macOS-12, notset, 3.10)	success	✅
install-pkg (windows-2022, app, 3.7)	success	✅
install-pkg (windows-2022, app, 3.10)	success	✅
install-pkg (windows-2022, lite, 3.7)	success	✅
install-pkg (windows-2022, lite, 3.10)	success	✅
install-pkg (windows-2022, pytorch, 3.7)	success	✅
install-pkg (windows-2022, pytorch, 3.10)	success	✅
install-pkg (windows-2022, lightning, 3.7)	success	✅
install-pkg (windows-2022, lightning, 3.10)	success	✅
install-pkg (windows-2022, notset, 3.7)	success	✅
install-pkg (windows-2022, notset, 3.10)	success	✅

These checks are required after the changes to src/lightning_lite/lite.py, src/lightning_lite/utilities/distributed.py, src/lightning_lite/wrappers.py.

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Thank you for your contribution! 💜

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[tchaton]

LGTM !