apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/component/PortalSettings.java/PortalSettings/postConstruct
class PortalSettings:  @PostConstruct
  private void postConstruct() {

    allEnvs = portalConfig.portalSupportedEnvs();

    for (Env env : allEnvs) {
      envStatusMark.put(env, true);
    }

    ScheduledExecutorService
        healthCheckService =
        Executors.newScheduledThreadPool(1, ApolloThreadFactory.create("EnvHealthChecker", true));

    healthCheckService
        .scheduleWithFixedDelay(new HealthCheckTask(applicationContext), 1000, HEALTH_CHECK_INTERVAL,
                                TimeUnit.MILLISECONDS);

  }