@Override
  public void init() throws ServletException {
    this.jsonFactory = new JsonFactory();
    this.sysctlOutRef = new AtomicReference<>(null);
  }
A servlet to print system specific configurations that are not exposed via JMX.
Currently it exposes
- kernel configs
- network configs
- memory configs

/system?refresh=true will run sysctl command again
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/services/impl/SystemConfigurationServlet.java