* use yapf to format all python file

* yapf exclude two unittests file for they rely on writing and reading file, and format will break them

* disable diff_py_file because too many diff files cause command following failed

add __all__=[] to python files not in API public list; import * only support in API public list files (#32643)

* Support list and tuple for parameters of layer_norm, multiprocess_reader, DatasetFolder and ImageFolder.

* add unittest for layer_norm.

* add require gpu for example.

* upgrade comment string to raw string

* fix string in

* fix string with ' '

* revert update on comments

* upgrade only necessary

* fix sample code checker

* fix comments with '''

* disable ut test_parallel_executor_fetch_isolated_var,test=document_fix

* test for limiting ut exec time as 15S

* fix an error caused by cannot find ut

* fix some error

* can not find test_transformer

* fix error caused by ut not run in windows

* fix error caused by Compiler Options

* fix error caused by setting timeout value as 15 in python/paddle/tests/CMakeLists.txt

* setting timeout value to 120s for old ut

* add the timeout value setting

* fix error caused by ut only run in coverage_ci

* add analyzer_transformer_profile_tester

* fix some error

* fix some error

* fix error with inference option

* fix error with inference option setting as ON_INFER

* add some ut to set timeout

* modified some option

* fix error

* fix some timeout error

* fix error

* fix error

* fix timeout for test_analyzer_bfloat16_resnet50

* fix error

* setting timeout properity for some ut

* first pr for new ut timeout as 15S

* Add example for cache and buffered, test=develop, test=document_fix

* remove paddle.readers API. test=develop

test=develop

Replace the 'spawn' start method with 'fork' start method for multiprocessing, on MacOS with python>=3.8 (#27317)

* Replace the 'spawn' start method with 'fork' start method for multiprocessing, on MacOs when python>=3.8

test=develop

* fix chain doc, test=develop, test=document_preview

* fix doc of default_main_program, multiprocess_reader

* update API.spec

* fix comment

Modify doc for shuffle, firstn, save_vars, load_vars, L1DecayRegularizer, L2DecayRegularizer (#20287)

* modify shuffle, firstn, regularizer, load_vars, save_vars, test=develop, test=document_fix

* modify compose en

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop

* test=develop,test=document_fix

* test=develop,test=document_fix

* modify map_reader en test=develop

* improve the docs of load_inference_model&load_params&load_persistables&chain.

* add multi process reader
test=develop

test=develop

test=develop

test=develop

test=develop

test=develop

* add multiprocess_reader

* add multiprocess_reader to reader decorator

* support piped multi process reader

* revert v2 decorator

* add comment to multiprocess_reader

* optimize code

* use ujson to speed up json serialize/deserialize

* add assert to multiprocess_reader

* update comment of multiprocess_reader

* optimize ujson import, handle error case

* optimize import ujson

* remove ujson from requirements.txt

* add import sys to decorator.py