apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AccessKeyServiceWithCache.java/AccessKeyServiceWithCache/afterPropertiesSet
class AccessKeyServiceWithCache:  @Override
  public void afterPropertiesSet() throws Exception {
    populateDataBaseInterval();
    scanNewAndUpdatedAccessKeys(); //block the startup process until load finished

    scheduledExecutorService.scheduleWithFixedDelay(this::scanNewAndUpdatedAccessKeys,
        scanInterval, scanInterval, scanIntervalTimeUnit);

    scheduledExecutorService.scheduleAtFixedRate(this::rebuildAccessKeyCache,
        rebuildInterval, rebuildInterval, rebuildIntervalTimeUnit);
  }