#To list any process listening to the port 8080:
lsof -i:8080
#To kill any process listening to the port 8080:
kill $(lsof -t -i:8080)
#or more violently:
kill -9 $(lsof -t -i:8080)
Check this gist
https://gist.github.com/abhagsain/620120eb99cc5944d478a23757f9e00f