When I set the 2 or more each designate service workers,
those service_status was not working.
In this case, The 'HeartBeatEmitter.start' is called
by child processes.
And The 'HeartBeatEmitter._emit_heartbeat' is called
by Parent process.
Parent process' '_running' value never change to TRUE
on parent process.
So in this case, designate isn't emitted the heartbeat.
Change-Id: I1338d2ca180274ae84d4b358ff467e6655eb8022
Closes-Bug: #1827070
9214a42a8e