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 
Executor service is not a thread, so better to put executor in the name vs
thread
On Sep 30, 2014 8:56 AM, "yaphet" <notifications@github.com> wrote:

> In core/src/main/java/tachyon/worker/TachyonWorker.java:
>
> > @@ -131,9 +134,9 @@ public static void main(String[] args) throws UnknownHostException {
> >
> >    private final DataServer mDataServer;
> >
> > -  private Thread mHeartbeatThread;
> > +  private ScheduledExecutorService heartbeatService;
>
> rename heartbeatService to mHeartbeatService it's better than
> mHeartbeatThread?
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/amplab/tachyon/pull/448/files#r18226691>.
>