Python periodic task using oslo service

Question

I am trying to run a method periodically(60 seconds). I am using oslo service to do so. Below is the snippet.

import time
from oslo_service import periodic_task

class MyClass(periodic_task.PeriodicTasks):
    def __init__(self):
        super(periodic_task.PeriodicTasks, self).__init__()

    @periodic_task.periodic_task
    def hello(self):
        print "hello"

    def sleeptime(self):
        time.sleep(5000)

myobj = MyClass()
myobj.hello()
myobj.sleeptime()

"hello" gets printed just once. What am i doing wrong here ?