* Add lookahead optimizer

* add unittest for lookahead optimizer

test=develop

* add doc string for LookaheadOptimizer

test=develop
test=document_preview

* add API spec for lookahead

test=develop
test=document_preview

* modify api spec

test=develop
test=document_preview

* modified doc string

* modify the test file

test=develop
test=document_preview

* modify doc string

test=develop
test=document_preview

* fix sync mode hang in transpiler
* remove sync mode in send/recv
* replace PADDLE_ENFORCE with PADDLE_ENFORCE_NE

* Fix arg do_model_average in param_attr

test=develop

* Update api spec

test=develop

test=develop

* use PE for compiler
test=develop

* add local user data conversion into full_pascalvoc_test_preprocess.py
test=develop

* change PADDLE_ENFORCE to PADDLE_ENFORCE_GE
test=develop

* change according to reviews
test=develop

* Implement the operator with sprase matrix multiply

* Update the URL of mklml library.

test=develop

* Disable MKLML implematation when using no-linux.

test=develop

* optimize bp with mkl sparse matrix
test=develop

* add pybind interface to get all inplace ops, test=develop

* enhance OpTest to check whether the consistency of operator when using and not using inplace, test=develop

* handle corner cases in op_test, test=develop

* support outputs without tensor holder_, like XShape in reshape_op, test=develop

* fix bug, some op has GradOpMaker, but actually no grad_op in OpInfoMap, test=develop

* use reshape_grad instead of reshape in FlattenGradOp, test=develop

* fix error debug dims info for variables like XShape, test=develop

* change computational order in sum_op to relieve computation difference using inplace, test=develop

* add inplace_atol to check group_norm, and skip inplace_grad for mkldnn, test=develop

* follow sneaxiy's comments, test=develop

* remove unused DefaultGradOpDescMaker in mkldnn op, test=develop

* add diag init in Uniform_random op test=develop

* modify api.spec test=develop

* fix unform_batch_size_like maker test=develop

* add diag_num and diag_step assert check test=develop

* stronger the error message of tensor's mutable_data

test=develop

* update error message

test=develop

test=develop

* Add generalized Conv+Activation MKLDNN fuse pass creation Part2
test=develop

* Undefined behaviour of GetAttrIfExists<> FIX
test=develop

For small case use 1D block is better than 2D block.

Refer to this issue: #19275

* replace part of PADDLE_ASSERT to PADDLE_ENFORCE

test=develop

* remove unused fallback_alloc_size_

* add unit-test of CUDAPinnedAllocator

test=develop

test=develop, test=document_preview

* Implement the operator with sprase matrix multiply

* Update the URL of mklml library.

test=develop

* Disable MKLML implematation when using no-linux.

test=develop

* Ignore the deprecated status for windows

test=develop

* cuda optimie for dropout

* remove tmp swp file

* fix compile error test=develop

* test=develop optimize the cuda realization of dropout op

* remove unsed code test=develop

* remove tmp file test=develop

* fix mask rcnn bug:
1. affine channel fuse (diff)
2. condition block op (memory leak)
3. merge lod tensor op (diff)
4. memroy optim (diff)
test=develop

* fix ci aboud PADDLE_ENFOCE
fix merge lod infer op ut
test=develop

* add matrch_matrix_tensor op test=develop

* fix ignore unittest if with_mkl=off test=develop

* clean code and rm is_test param test=develop

* modify API.spec test=develop

* rm useless code in search_compute.h test=develop

* modify api.spec test=develop

* modify default_grad.spec test=develop

* Add API test code test=develop

* clean code in search_computer.h

* modify PADDLE_ENFORCE and clean search_compute.h test=develop

* fix code style test=develop

* fix compilation issue in windows vs2017, test=develop

* fix gtest lib not found issue, test=develop

add fl_listen_and_serv op for Federated_learning and fl_distribute_transpiler add this op to pserver program . This op just listen the endpoint and sum&scale.

remove the warning for reminding user to avoid using the OriginProgram method, test=develop (#19244)

This log information may annoy users who don't need to care about it.

* print error code if cuda related API fails

* make PADDLE_ENFORCE_EQ support cannot to string types, test=develop

* follow huihuang's comments, test=develop

* fix REGISTER_OP_WITHOUT_GRADIENT
test=develop

Unset unittests http_proxy env to avoid timeout.

* imporve the doc of decorate_reader API, test=develop

* udpate API.spec, test=develop

modify checkMacPython2 and checkMacPython3 function to ensure python version used for paddle installation is EQ/GT than 2.7.15 on MacOS; modify checkMacPaddleVersion function to ensure paddle version is release version, because paddle don't have develop version on MacOS.

* fix temporal_shift OP PADDLE_ENFORCE. test=develop

* fix HasInput/HasOutpu ENFORECE. test=develop

* remove unused inference_transpiler unit-tests

test=develop

* remove InferenceTranspiler usage in quantize_transpiler.py

test=develop

* change the top1 comparison to mAP comparison
test=develop

* change the mobilenet-ssd tester demo data and batch_size settings
test=develop

* add exception exit on error example codes test=develop