* refine parallelExecutor
test=develop

* Polish op_handle
test=develop

* Remove unnecessary op_handle
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* Fix Travis CI
test=develop

* Fix fetch bug
test=develop

* Remove WaitInputVarGenerated

* Fix OpHandleBase::Run
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* debug
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* use origin fetch_op_handle
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* Revert op_handle_base.cc
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* Polish code
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* Fix OpHandleBase::Run
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* code refine

* test CI and CE
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* fix OpHandle::Run
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* refine AllReduceOpHandle
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* Polish code
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* fuse all_reduce
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* add fuse_parameter_groups_size
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* Polish code
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* Fix travis-ci
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* Add SetGroupAccordingToLayers and SetGroupAccordingToGroupSize
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* Add SetGroupAccordingToMemorySize
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* fix multi_devices_graph
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* reset params_grads
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* Polish code
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* wip allreduce in op

* wip

* wip

* wip

* wip adding test

* wip for conflict with mp mode

* fix tests test=develop

* fix cpu build test=develop

* fix travis clang format test=develop

* fix cpu build test=develop

* update api.spec test=develop

* delete comment test=develop

* fix cpplint test=develop

* fix test=develop

* follow comment test=develop

* add file test=develop

* fix build test=develop

* update test=develop

* to be compatible with sync_bn, and fix mp mode in develop test=develop

* 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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* refine parallel_exe
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* rename shared_var_device

* code refine

* add test_weight_decay

* remove Sort
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* Add SortForReduce
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* code refine
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* follow comment
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* wip

* wip

* wip

* wip for test

* add fp16 tests test=develop

* fix cpu build test=develop

* fix test=develop

* fix py3 tests test=develop

* fix lr_scheduler dtype test=develop

* fix test=dvelop

* test fix ci compile test=develop

* fix build and merge test=develop

* fallback momentumop change to general test=develop

* make fp16 lr schedule simple test=develop

* fix ut test=develop

* fix tests test=develop

* remove fp16 learning rate cast test=develop

This reverts commit 3d750f9c.

* refine parallel_executor

* remove uncessary code
test=develop

* wip

* wip

* wip

* wip for test

* add fp16 tests test=develop

* fix cpu build test=develop

* fix test=develop

* fix py3 tests test=develop

* fix lr_scheduler dtype test=develop

* fix test=dvelop

* test fix ci compile test=develop

* fix build and merge test=develop

* fallback momentumop change to general test=develop

* wip multi process multi gpu dist training

* workable for p2p

* update test=develop

* change back env name test=develop

* fix alloc init

* fix cpu build test=devlop

* fix mac tests test=develop

* refine code

* refine test=develop

test=develop

test=develop

* fix input<tensor>
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* fix split_ids
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* ElementwiseMul should not support SelectedRows

* fix scale op
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* change GetTensorFromVar() method to GetTensorOrSelectedRowsFromVar()

* fix operator

* refine MultiOutput

* fix MultiOutput
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* disable test_dist_save_load
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* fix elementwise_op
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* add get_sparse_as_op
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* add info for check
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* rename get_sparse_as_op with extract_rows_as_op.
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* elementwise doesn't support selected_rows

* fix regularizer

* remove extract_rows_as
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* fix ci
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* add test for sum_op

* fix regularizer
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*  test=develop

* fix pserver weight decay multi inputs test=develop

Fix code to support cpplint syntax check

test=develop