public void stop() {
    if (started.compareAndSet(true, false)) {
      if (scheduler != null) {
        Utils.shutDownExecutorService(scheduler, config.nettyMetricsStopWaitTimeoutSeconds, TimeUnit.SECONDS);
        logger.info("De-scheduled for collecting netty internal metrics");
      }
    }
  }
Stop collecting metrics. This method would stop this singleton effectively. Do not reuse this single after
calling this method.
ambry-commons/src/main/java/com/github/ambry/commons/NettyInternalMetrics.java