* add the support for multi-node training

update cumsum api and fix up the cumsum op

* fix prelu for compatibility with saved model of old version

* reshape alpha

* Add oneDNN relu6 op

* Lint fixes

* fix merge3 test=develop

* add paddle.fleet.AsyncOptimizer
Co-authored-by: Ndongdaxiang <dongdaxiang@baidu.com>

* add pin memory control

* fix buffered reader init problem

* fix unittest error

* add unittest for coverage

* add cuda pinned place branch

* add unittest

* add skip when not gpu

* support multi-ps training mode for fleetrun; test=develop

1. update document template for unary elementwise layers(a.k.a. activation layer);
2. remove generate_op_noattr and use generate_activation instead; remove redundant function copies;
3. minor update for docstring to fix rst format errors.
4. fix doc for Rsqrt OP
5. add sample code for each activation separately;
6. remove the unused deprecated decorator.

* Change use_quantizer attribute name and data type

* Fix problem with setting attribute

* Add changes due to review

* Small change in function

* Restore use_quantizer attr for compatibility

* enable check_dygraph for mkldnn activation tests

* TestMKLDNNSwishDim4 float32->self.dtype

* refine unsqueeze, test=develop

* update unsqueeze, test=develop

* refine unsqueeze, test=develop

* refine unsqueeze, test=develop

* update

* remove None, test=develop

* follow comments

* support bool

* update doc

* follow comments

* merge develop

[Dy2Stat-ErrorMessage]Optimize error value to improve readability when error raised in runtime.  (#25970)

* don't remove op_callstack

* [Dy2Stat-ErrorMessage] Optimize error value to improve readability if error raised in run-time. 
  1. update op_callstack with original information;
  2. simplify error value to improve readability if error raised in run-time.

* Fix error in Python3. 

* fix large scale KV 
* fix single training using async ssa graph

* add flags_call_stack_level

* update

* refine code

* add limit support for load_dygraph loading jit.save result

* simplify unittest

* add unittests for coverage

* remove encoding limit of loading extra var info

* [Dy2Stat-ErrorMessage]Enhance original error and create new exception. test=develop

* Delete redundant code and change func name to create_and_update_origin_info_map. 

* optimize loop_transformer. 

* fix bug in print_transformer.

* Modify code according to the comments.

* test=develop,test=document_fix, remove the out args

* fleet_util move to paddle.fleet
Co-authored-by: NWuHaobo <wuhaobo1994@gmail.com>
Co-authored-by: Ntangwei12 <tangwei12@baidu.com>

* refine stack in dygraph mode, test=develop

* update stack, test=develop

* rename Variable to Tensor, test=develop

* add name args to fluid.layers.stack, test=develop

* follow comments

* update doc

* update doc

* follow comments

* move dataset to fleet
test=develop

* fix
test=develop

* fix
test=develop

* fix
test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* Add oneDNN fusion_gru kernel and fix fc+gru pass
test=develop

* Formatting changes
test=develop

* Lint fixes
test=develop

* Add memory::format_tag::any to GRU weights
test=develop

* Fix build with CUDA

* Fix build with CUDA v2

* add heter ps mode

* code style
test=develop

* add with_pslib
test=develop

* unitest
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* code style
test=develop

* test monitor
test=develop

* prepare trainer
test=develop

* code style
test=develop

* add paddle.utils.deprecated.

* add docstring. test=develop

* add alias paddle.utils.deprecated. test=develop

* rm deprecated in python/paddle/fluid/annotations.py. test=develop

* 1. check version before warning. 2. bug fix. test=develop

* bug fix. test=develop

* use paddle.fluid.require_version. test=develop

* fix doc

* fix doc. test=develop

* fix doc. test=develop

* bug fix. test=develop

* use packaging.version. test=develop.

* enhance doc. test=develop

* add compare_version function. test=develop

* add version.py. test=develop

* remove packaging. test=develop

* move compare_version to deprecated.py. test=develop

* remove print. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* fix. test=develop

* inline. test=develop

* fix. test=develop

* add uncombined_weight_to_state_dict API

update the sort api, delete unused ouput index tensor

Add dgc to fleet meta optimizer, rm dgc from optimizer all

* generate context during compile

* Add some error messages for the op without double grads.

* fix the test_imperative_double_grad UT.

* add apply for Layer

* add fleetrun command for distributed running; test=develop