public void initializeOperationControllerMetrics(final Thread requestResponseHandlerThread) {
    requestResponseHandlerThreadRunning = () -> requestResponseHandlerThread.isAlive() ? 1L : 0L;
    metricRegistry.gauge(
        MetricRegistry.name(NonBlockingRouter.class, requestResponseHandlerThread.getName() + "Running"),
        () -> requestResponseHandlerThreadRunning);
  }
Initializes a {@link Gauge} metric for the status of {@code RequestResponseHandlerThread} of an
{@code OperationController}, to indicate if it is running
or not.
@param requestResponseHandlerThread The {@code RequestResponseHandlerThread} of which the status is
                                    to be monitored.
ambry-router/src/main/java/com/github/ambry/router/NonBlockingRouterMetrics.java