They should be hanged until death. In country like India they roam freely and every now and then rape happens, nowadays they won't even spare small kids. Every country should have rule like Saudi where they kill them in the middle of the road, so that fear should be in their minds.
Thousands of rapes are happening in Saudi Arabia every year. How many of these rapists are executed in the public? Last year (2016), the only cases of death penalty for rape occurred when foreign workers were found guilty for the rape of Saudi women. There are more than a million house maids in Saudi Arabia, and 99% of them are raped on a daily basis. I never heard any Saudi getting punishment for these crimes.