@Override
  public void close() throws IOException {
    if (scheduler != null) {
      shutDownExecutorService(scheduler, config.updaterShutDownTimeoutMinutes, TimeUnit.MINUTES);
    }
    cachedAccountService.close();
  }
Fetches all the accounts and containers that have been created or modified in the mysql database since the
last modified/sync time and loads into in-memory {@link AccountInfoMap}.
ambry-account/src/main/java/com/github/ambry/account/MySqlAccountService.java