Recreate iterator on the end of epoch instead of at begininng
Hi @austinzh It looks like your PR relates to the Keras component. Please submit it to the github.com/keras-team/keras repository instead. Thank you for your contribution!
@fchollet, @qlzh727 @gbaned A little confused. I found the master of keras-team/keras is not the same as the keras in tensorflow repo.
What is the proper process of contribute to the keras version that tensorflow now integrate with?
We already create a data_iterator at the beginning. No point to recreate it again at the beginning of epoch.
This should fix issue like [this](https://stackoverflow.com/questions/69843184/using-sagemaker-pipe-mode-with-an-s3-directory-of-tfrecords/77532311#77532311)
Also will improve cool start time when use data that have slow initialization and do prefetch or buffering at init. 