public List<JVMClusterUtil.RegionServerThread> getLiveRegionServers() {
    List<JVMClusterUtil.RegionServerThread> liveServers = new ArrayList<>();
    List<RegionServerThread> list = getRegionServers();
    for (JVMClusterUtil.RegionServerThread rst : list) {
      if (rst.isAlive()) liveServers.add(rst);
      else LOG.info("Not alive " + rst.getName());
    }
    return liveServers;
  }
@return List of running servers (Some servers may have been killed or aborted during lifetime
        of cluster; these servers are not included in this list).
hbase-server/src/main/java/org/apache/hadoop/hbase/LocalHBaseCluster.java