* Previous `mp_group` is renamed to `slice_gruop`, indicating that all workers in the group receive the same input batch, and process a slice of the input. `mp_gruop` will be deprecated in our next release.
* Previous `mp_group` is renamed to `slice_group`, indicating that all workers in the group receive the same input batch, and process a slice of the input. `mp_group` will be deprecated in our next release.