@Nullable
    public static TNetworkAddress getComputeNodeHost(ImmutableMap<Long, ComputeNode> computeNodes,
                                                     Reference<Long> computeNodeIdRef) {
        ComputeNode node = getComputeNode(computeNodes);
        if (node != null) {
            computeNodeIdRef.setRef(node.getId());
            return new TNetworkAddress(node.getHost(), node.getBePort());
        }
        return null;
    }
@Test
    public void testNoAliveComputeNode() {
        ImmutableMap.Builder<Long, ComputeNode> builder = ImmutableMap.builder();
        for (int i = 0; i < 6; i++) {
            ComputeNode node = new ComputeNode(i, "address" + i, 0);
            node.setAlive(false);
            builder.put(node.getId(), node);
        }
        ImmutableMap<Long, ComputeNode> nodes = builder.build();
        Reference<Long> idRef = new Reference<>();
        TNetworkAddress address = SimpleScheduler.getComputeNodeHost(nodes, idRef);
        Assert.assertNull(address);
    }