code: public static InstrumentedExecutorService newSingleThreadExecutor(MetricRegistry registry, String name) {
          return new InstrumentedExecutorService(Executors.newSingleThreadExecutor(), registry, name);
      }
docs: Creates an InstrumentedExecutor that uses a single worker thread operating
  off an unbounded queue. (Note however that if this single
  thread terminates due to a failure during execution prior to
  shutdown, a new one will take its place if needed to execute
  subsequent tasks.)  Tasks are guaranteed to execute
  sequentially, and no more than one task will be active at any
  given time. Unlike the otherwise equivalent
  {@code newFixedThreadPool(1)} the returned executor is
  guaranteed not to be reconfigurable to use additional threads.
  
  @param registry the {@link MetricRegistry} that will contain the metrics.
  @param name     the (metrics) name for this executor service, see {@link MetricRegistry#name(String, String...)}.
  @return the newly created single-threaded Executor
  @see Executors#newSingleThreadExecutor()