code: public static void startSinks(String metricsConfFile) {
      synchronized (MetricsSystem.class) {
        if (sSinks != null) {
          LOG.info("Sinks have already been started.");
          return;
        }
      }
      if (metricsConfFile.isEmpty()) {
        LOG.info("Metrics is not enabled.");
        return;
      }
      MetricsConfig config = new MetricsConfig(metricsConfFile);
      startSinksFromConfig(config);
    }
docs: Starts sinks specified in the configuration. This is an no-op if the sinks have already been
  started. Note: This has to be called after Alluxio configuration is initialized.
  
  @param metricsConfFile the location of the metrics configuration file