Hold and reuse the CheckpointReader in _CheckpointRestoreCoordinator
Hold and reuse the CheckpointReader in _CheckpointRestoreCoordinator

Tiny improvement to actual execution speed, just seems rather inefficient to open the same file twice or more in quick succession.

PiperOrigin-RevId: 399507429
Change-Id: I5667546be3ef3402de62ee9f0552b2762a139032

gautam1858/tensorflow,Intel-tensorflow/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow-experimental_link_static_libraries_once,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow-pywrap_saved_model,yongtang/tensorflow,Intel-tensorflow/tensorflow,yongtang/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,Intel-tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_tf_optimizer,gautam1858/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_tf_optimizer,yongtang/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,karllessard/tensorflow,Intel-Corporation/tensorflow,Intel-tensorflow/tensorflow,yongtang/tensorflow,karllessard/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,tensorflow/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow,Intel-tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_saved_model,yongtang/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow,gautam1858/tensorflow,yongtang/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,Intel-Corporation/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,paolodedios/tensorflow,tensorflow/tensorflow,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-pywrap_saved_model,Intel-Corporation/tensorflow,Intel-tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,tensorflow/tensorflow-pywrap_saved_model,Intel-Corporation/tensorflow,tensorflow/tensorflow-pywrap_saved_model,gautam1858/tensorflow,Intel-tensorflow/tensorflow,Intel-Corporation/tensorflow,paolodedios/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,tensorflow/tensorflow-experimental_link_static_libraries_once,tensorflow/tensorflow-experimental_link_static_libraries_once,gautam1858/tensorflow,tensorflow/tensorflow,yongtang/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,Intel-tensorflow/tensorflow,Intel-Corporation/tensorflow,tensorflow/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once,tensorflow/tensorflow-pywrap_tf_optimizer,tensorflow/tensorflow-experimental_link_static_libraries_once,Intel-tensorflow/tensorflow,paolodedios/tensorflow,karllessard/tensorflow,Intel-tensorflow/tensorflow,tensorflow/tensorflow,karllessard/tensorflow,paolodedios/tensorflow,paolodedios/tensorflow,tensorflow/tensorflow,tensorflow/tensorflow-pywrap_saved_model,yongtang/tensorflow,tensorflow/tensorflow,gautam1858/tensorflow,paolodedios/tensorflow,paolodedios/tensorflow,Intel-Corporation/tensorflow,Intel-tensorflow/tensorflow,Intel-Corporation/tensorflow,karllessard/tensorflow,tensorflow/tensorflow-pywrap_tf_optimizer,yongtang/tensorflow,gautam1858/tensorflow,tensorflow/tensorflow-experimental_link_static_libraries_once