Motivation:
Traffic shaping needs more accurate execution than scheduled one. So the
use of FixedRate instead.
Moreover the current implementation tends to create as many threads as
channels use a ChannelTrafficShapingHandlern, which is unnecessary.
Modifications:
Change the executor.schedule to executor.scheduleAtFixedRate in the
start and remove the reschedule call from run monitor thread since it
will be restarted by the Fixed rate executor.
Also fix a minor bug where restart was only doing start() without stop()
before.
Result:
Threads are more stable in number of cached and precision of traffic
shaping is enhanced.