用H5py + 自定义Generator + 调batch size
https://github.com/fchollet/keras/issues/1627
https://github.com/fchollet/keras/issues/2674
https://github.com/fchollet/keras/issues/2708
https://github.com/fchollet/keras/issues/2674
https://groups.google.com/forum/#!topic/keras-users/m4mRpBgzrLQ
https://stackoverflow.com/questions/42641824/keras-model-fit-generator-several-times-slower-than-model-fit
GitHUb的issue，stackoverflow，Google是解决bug的必备啊