* Refactor ParallelExecutor
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* extract Reduce and AllReduce mode from MultiDevSSAGraphBuilder
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* Refactor MultiDevSSAGraphBuilder
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* Remove enable_data_balance
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* code refine
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* remove data balance
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* refine ScaleLossGradOp
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* remove uncessary file
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* code refine
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* modify  function name
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* follow comments
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* add is_distribution field
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* set is_distribution
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* fix DistSSAGraphBuilder
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add module cleanup
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* refine parallel_executor

* remove uncessary code
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* follow comments. test=develop

* Fix typo

* fix compile error. test=develop

* merge develop branch. test=develop

* Remove set_equal

* Polish code

* Delete unused functions

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* polish code. test=develop

* follow comment

* polish code.

* fix windows compile error. test=develop

* fix op handle.

* rerun ci. test=develop

* rerun ci. test=develop

* rerun macci. test=develop

* polish code. test=develop

* rewrite sort code. test=develop

* remove unused code. test=develop

* fix tests. test=develop

* fix conflict. test=develop

* follow comment. test=develop

* merge develop branch. test=develop

* fix tests. test=develop

* remove ToTypeIndex. test=develop

* rerun ci. test=develop

2. Seperate the lock of kids and vars in Scope

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Revert "Merge pull request #14798 from PaddlePaddle/revert-14786-revert-14782-revert-14398-imperative"

This reverts commit b1d3a1c8, reversing
changes made to f1fb64b1.

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