* [CodeStyle][F821] fix remained F821 issues

* refine comment

* fix _set_item

[CodeStyle][F821] fix undefined variables due to missing imports, misspelled variable names (#47899)

* `hann` -> `_hann`

* `false` -> `False`

* a missing passed argument `reduce_all`

* some missing imports

* `device_type` -> `heter_device_type`

* `PKVClient` -> `KVClient`

* fix some typos and missing imports

* fixed cond state

* fixed cond state

* add recompute doc.

* add recompute doc.

* add recompute doc.

* update.

* update.

* add c_concat pass for reshard

* add unittest

* XPU support eager mode

* add unittest for XPU eager mode

* minor bugfix

* minor bugfix, test=kunlun

* correct copyright info

* 1. remove unsed vars/funcs
2. ProcessGroupBKCL inherit from ProcessGroupStream

* bugfix for fp16 in eager mode multi-card, test=kunlun

* rebase & fix a few issues

* use new processgroup interface, test=kunlun

* fix compile issue, test=kunlun

* fix insert concat op

* fix fp16 assert

* fix flake8 CodeStyle E266

* fix comments

[Auto Parallel] Sharding Optimization：Partition Algorithm & Stage2 Parameter Bucket communication  (#47180)

* partition param by order

* add logging

* reorder opt

* config

* stage2 bucket

* update unitest

* [CodeStyle][py2][U004] unecessary explicit `object` inheritance in class definition

* fix an increment

* fp16 pass support assign op

* choose assign op exec mode

* add unittest

* add cmakelist

* [CodeStyle][E262][E265] make comments start with `# `

* flake8 config

* expand op donot use naive data parallel

* fix unittest

* support sharding stage2 + mp hybrid_parallel.

* fix the group of check_nan_inf.

* update hcg.

* [CodeStyle][py2][U008] remove unnecessary args in `super()`

* remove remained args

* revert changes in test_pylayer_op

* Revert "revert changes in test_pylayer_op"

This reverts commit ff185a9ae738afac3b0264f61bde6c6b7f72e7c4.

* revert some changes in example code

* add unbalanced data

* fix utest

* [CodeStyle][E711] use `is`/`is not` for comparison with `None`

* `self.assertTrue($A is None)` -> `self.assertIsNone($A)`

* `self.assertTrue($A is not None)` -> `self.assertIsNotNone($A)`

* `self.assertFalse($A is None)` -> `self.assertIsNotNone($A)`

* `self.assertEqual($A, None)` -> `self.assertIsNone($A)`

* `self.assertNotEqual($A, None)` -> `self.assertIsNotNone($A)`

* [CodeStyle][E712] use `if cond`/`if cond is True` for comparison with `True`

* revert changes in fluid

* revert unrelated file

* revert changes in norm

* revert changes in auto_parallel_amp

* fix norm and auto_parallel_amp

* revert a typo fix due to fixed at #47477

* [CodeStyle][py2] remove `six` package (part2)

* six.ensure_str

* remove unused `import six`

* remove six from BUILTIN_LIKELY_MODULES

* remove six in example code

* remove some decode

* try to fix example code

* fix MockEtcdClient get/get_prefix returns data type

* fix MockEtcdClient get_prefix returns data

* fix MockEtcdClient get returns data

* remove `six` in pypi and conda requirements

* fix MockEtcdClient add_watch_callback/add_watch_prefix_callback returns data type

* refine MockEtcdClient

* [Auto Parallel] Improve the c++ dist attr

* [Auto Parallel] Modify test_program.py

* [Auto Parallel] Add the missiong import

* add fused_allreduce_gradients_with_group

* add scale

* fix ci

* fix engine build method

* fix import

* update engine cost

* update raise error

* update cmakelist

* revert optimizer

* revert optimizer

* fix unittest

* fix unittest
Co-authored-by: Ncaozhou <caozhou@radi.ac.cn>