* 1. implement StopAll in ListenAndServOp
2. make pserver receive the SIGINT and SIGTERM from outside
3. add unittests for listen_and_serv_op in python

* 1. add blocking queue set to record queue
2. aware all blocking queue when exit and exit gracefully

* 1. Remove comment lines from blocking_queue.h
2. Implement SignalHandler and move all global vars and funcs into it

* 1. Make code follows the style check
2. Move the SignalHandler out of the unnamed namespace

* 1. Make yapf happy

* 1. Call Stop() in destructor to release the resource allocated by ListendAndServOp
2. Change exit status to EXIT_SUCCESS after handling the signal from outside
3. Remove the mis-usage of REMOVE_ITEM in unittests

* 1. use DISABLE_COPY_AND_ASSIGN
2. use program once macro only

* update benchmark doc

* update by comment

Fix and optimize async distribute lookup table

* update

* remove warning

* Update test_paddle_inference_api_impl.cc

Fix DataTransFunc

Move check_nan_inf to operator

fix inference build on mac

fix nightly build and build script error

overlap send ops and backward ops

fix inference_lib_dist deps

* fix develop build issue

* fix google style

* cpplint check only fluid

Fix test to use less gpu memory