@Override
    public List<String> getHosts(String segmentName, boolean isRealtime) throws IOException {
        assert isRealtime;

        RTSGroupInfo info = rtsGroupInfoMap.get(segmentName);
        if (info == null) {
            return null;
        }
        return Collections.singletonList(info.host());
    }
This segment pool cache all realtime segment fds.
indexr-server/src/main/java/io/indexr/server/rt/RealtimeSegmentPool.java