GitLab

* refactoring FlattenParamWrapper

- use a FlatParameter class to encapsulate the logic of
  flattening and expanding into views.
- this will make it easier to have multiple groups of flatten
  parameters

* fixed testing context issues for both temp files and temp dirs

* fixing test_fsdp_metadata

* fix pickling of FlatParameter

* fixed test_fsdp_optimizer_utils.py

* minor

* fix assert

* lint

* remove nesting from the test

* step 1.5: remove the code related unnecessary nesting support in FPW

* Update fairscale/nn/misc/flatten_params_wrapper.py
Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

* address comment
Co-authored-by: Min Xu <min.xu.public@gmail.com>
Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

* rename files

* add newly renamed file

* rename and move checkpoint activations related files

* add test files to ci list

* fix lint errors

* modify docs

* add changelog

* retain old path for now

* fix lint errors

* add another import test case

* fix merge conflict

* add missing test file

* param buckets
* unifying the buckets

* extracting the buckets in a dedicated class, fixing the resize_ bug
* adding a unit test
* copyright

* [feat]: checkpoint and normalization

- added special handling of BN for track_running_stats and checkpointing
- we test BN/LN and checkpointing
- we test them with mixed precision

* [test]: add peak mem in checkpoint test

* more debugging

* new test

* more fix

* better collection of debug in case of future failures

* update the comment

* typo

* comment

* clarify

* better wording

* [bug]: not all CUDA memory is freed when model is deleted

* fixed memory leak

- without this, peak memory will be high when more than one model
  is trained (i.e. first model leave staff around pushing up the
  peak memory when the second model runs)

* addressed comments

* fix

* changelog

* Add fairscale.utils.containers
Co-authored-by: Min Xu <24926999+min-xu-ai@users.noreply.github.com>

* Add fairscale.nn.misc.checkpoint_activations
Co-authored-by: Sam Shleifer <sshleifer@gmail.com>
Co-authored-by: Min Xu <24926999+min-xu-ai@users.noreply.github.com>
Co-authored-by: Sam Shleifer <sshleifer@gmail.com>

* working around broken mypy