[TINKERPOP-2486] Client does not load balance requests across available connections

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.8, 3.4.9
• Fix Version/s: 3.6.0
• Component/s: driver
• Assignee: Stephen Mallette
• Reporter: Divij Vaidya
• Created: 08/Dec/20 02:54
• Updated: 26/Jul/23 00:01
• Resolved: 05/Oct/21 17:18

Description

The client does not load balance requests across connections in a threadpool which cause a request failing with timeout even when a connection is available. To verify this, the following test fails:

@Test
public void shouldBalanceConcurrentRequestsAcrossConnections() throws InterruptedException {
    final int connPoolSize = 16;
    final Cluster cluster = TestClientFactory.build()
            .minConnectionPoolSize(connPoolSize)
            .maxConnectionPoolSize(connPoolSize)
            .create();
    final Client.ClusteredClient client = cluster.connect();
    client.init();

    try {
        final RequestMessage.Builder request = client.buildMessage(RequestMessage.build(Tokens.OPS_EVAL))
                .add(Tokens.ARGS_GREMLIN, "Thread.sleep(5000)");
        final Callable<Connection> sendQueryCallable = () -> client.chooseConnection(request.create());
        final List<Callable<Connection>> listOfTasks = new ArrayList<>();
        for (int i=0; i<connPoolSize; i++) {
            listOfTasks.add(sendQueryCallable);
        }

        Set<String> channels = new HashSet<>();
        final List<Future<Connection>> executorSubmitFutures = executorServiceForTesting.invokeAll(listOfTasks);
        executorSubmitFutures.parallelStream().map(fut -> {
            try {
                return fut.get();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
            return null;
        }).forEach(conn -> channels.add(conn.getChannelId()));

        
        System.out.println(channels.size());

    } finally {
        cluster.close();
    }
}

Issue Links

• is duplicated by: TINKERPOP-2871 Borrowed count can be wildly incorrect