Modify  TachyonWorker Heartbeat sleeping to ScheduledExecutorService 

TachyonWorker's heartbeat thread is sleeping several milliseconds . 
JDK API ScheduledExecutorService's scheduleAtFixedRate method running a task after initial delay and subsequently with the given period. It's more fit for the heartbeat task .
And a TODO : split heartbeat thread into another class.
thanks 
"you mean heartbeat should submit task with difference time interval"

In keeping with the current behavior, yes.

If the behavior is to change, a reason should be given to justify the behavior change.  Since heart beats have many failure cases, I don't feel comfortable changing behavior without the failure cases being looked at.