public int getRequestedHostCount() {
    synchronized (hostNames) {
      return requested_count == 0 ? hostNames.size() : requested_count;
    }
  }
Get the requested host count.
This is either the user specified value or
the number of explicitly specified host names specified by the user.

@return number of requested hosts for the group
ambari-server/src/main/java/org/apache/ambari/server/topology/HostGroupInfo.java