public List<String> getBackends() {
        List<String> backends = new ArrayList<>();
        SystemInfoService infoService = GlobalStateMgr.getCurrentState().getNodeMgr().getClusterInfo();
        try (CloseableLock ignored = CloseableLock.lock(this.rwLock.readLock())) {
            for (Replica replica : replicas) {
                Backend backend = infoService.getBackend(replica.getBackendId());
                if (backend == null) {
                    continue;
                }
                backends.add(backend.getHost());
            }
        }
        return backends;
    }
@Test
    public void testGetBackends() throws Exception {
        LocalTablet tablet = new LocalTablet();

        Replica replica1 = new Replica(1L, 10001L, 8,
                -1, 10, 10, ReplicaState.NORMAL, 9, 8);
        Replica replica2 = new Replica(1L, 10002L, 9,
                -1, 10, 10, ReplicaState.NORMAL, -1, 9);
        tablet.addReplica(replica1, false);
        tablet.addReplica(replica2, false);

        Assert.assertEquals(tablet.getBackends().size(), 2);

    }