Examples with Future scala.concurrent.Future used on opensource projects

Example 1 with Future

use of scala.concurrent.Future in project flink by apache.

the class TaskManagerTest method testTriggerStackTraceSampleMessage.

// ------------------------------------------------------------------------
// Stack trace sample
// ------------------------------------------------------------------------
/**
	 * Tests sampling of task stack traces.
	 */
@Test
@SuppressWarnings("unchecked")
public void testTriggerStackTraceSampleMessage() throws Exception {
    new JavaTestKit(system) {

        {
            ActorGateway taskManagerActorGateway = null;
            // We need this to be a JM that answers to update messages for
            // robustness on Travis (if jobs need to be resubmitted in (4)).
            ActorRef jm = system.actorOf(Props.create(new SimpleLookupJobManagerCreator(null)));
            ActorGateway jobManagerActorGateway = new AkkaActorGateway(jm, null);
            final ActorGateway testActorGateway = new AkkaActorGateway(getTestActor(), leaderSessionID);
            try {
                final ActorGateway jobManager = jobManagerActorGateway;
                final ActorGateway taskManager = TestingUtils.createTaskManager(system, jobManager, new Configuration(), true, false);
                final JobID jobId = new JobID();
                // Single blocking task
                final TaskDeploymentDescriptor tdd = createTaskDeploymentDescriptor(jobId, "Job", new JobVertexID(), new ExecutionAttemptID(), new SerializedValue<>(new ExecutionConfig()), "Task", 1, 0, 1, 0, new Configuration(), new Configuration(), BlockingNoOpInvokable.class.getName(), Collections.<ResultPartitionDeploymentDescriptor>emptyList(), Collections.<InputGateDeploymentDescriptor>emptyList(), Collections.<BlobKey>emptyList(), Collections.<URL>emptyList(), 0);
                // Submit the task
                new Within(d) {

                    @Override
                    protected void run() {
                        try {
                            // Make sure to register
                            Future<?> connectFuture = taskManager.ask(new TestingTaskManagerMessages.NotifyWhenRegisteredAtJobManager(jobManager.actor()), remaining());
                            Await.ready(connectFuture, remaining());
                            Future<Object> taskRunningFuture = taskManager.ask(new TestingTaskManagerMessages.NotifyWhenTaskIsRunning(tdd.getExecutionAttemptId()), timeout);
                            taskManager.tell(new SubmitTask(tdd));
                            Await.ready(taskRunningFuture, d);
                        } catch (Exception e) {
                            e.printStackTrace();
                            fail(e.getMessage());
                        }
                    }
                };
                //
                // 1) Trigger sample for non-existing task
                //
                new Within(d) {

                    @Override
                    protected void run() {
                        try {
                            ExecutionAttemptID taskId = new ExecutionAttemptID();
                            taskManager.tell(new TriggerStackTraceSample(112223, taskId, 100, timeD, 0), testActorGateway);
                            // Receive the expected message (heartbeat races possible)
                            Object[] msg = receiveN(1);
                            while (!(msg[0] instanceof Status.Failure)) {
                                msg = receiveN(1);
                            }
                            Status.Failure response = (Status.Failure) msg[0];
                            assertEquals(IllegalStateException.class, response.cause().getClass());
                        } catch (Exception e) {
                            e.printStackTrace();
                            fail(e.getMessage());
                        }
                    }
                };
                //
                // 2) Trigger sample for the blocking task
                //
                new Within(d) {

                    @Override
                    protected void run() {
                        boolean success = false;
                        Throwable lastError = null;
                        for (int i = 0; i < 100 && !success; i++) {
                            try {
                                int numSamples = 5;
                                taskManager.tell(new TriggerStackTraceSample(19230, tdd.getExecutionAttemptId(), numSamples, Time.milliseconds(100L), 0), testActorGateway);
                                // Receive the expected message (heartbeat races possible)
                                Object[] msg = receiveN(1);
                                while (!(msg[0] instanceof StackTraceSampleResponse)) {
                                    msg = receiveN(1);
                                }
                                StackTraceSampleResponse response = (StackTraceSampleResponse) msg[0];
                                // ---- Verify response ----
                                assertEquals(19230, response.getSampleId());
                                assertEquals(tdd.getExecutionAttemptId(), response.getExecutionAttemptID());
                                List<StackTraceElement[]> traces = response.getSamples();
                                assertEquals("Number of samples", numSamples, traces.size());
                                for (StackTraceElement[] trace : traces) {
                                    // Look for BlockingNoOpInvokable#invoke
                                    for (StackTraceElement elem : trace) {
                                        if (elem.getClassName().equals(BlockingNoOpInvokable.class.getName())) {
                                            assertEquals("invoke", elem.getMethodName());
                                            success = true;
                                            break;
                                        }
                                    }
                                    assertTrue("Unexpected stack trace: " + Arrays.toString(trace), success);
                                }
                            } catch (Throwable t) {
                                lastError = t;
                                LOG.warn("Failed to find invokable.", t);
                            }
                            try {
                                Thread.sleep(100);
                            } catch (InterruptedException e) {
                                LOG.error("Interrupted while sleeping before retry.", e);
                                break;
                            }
                        }
                        if (!success) {
                            if (lastError == null) {
                                fail("Failed to find invokable");
                            } else {
                                fail(lastError.getMessage());
                            }
                        }
                    }
                };
                //
                // 3) Trigger sample for the blocking task with max depth
                //
                new Within(d) {

                    @Override
                    protected void run() {
                        try {
                            int numSamples = 5;
                            int maxDepth = 2;
                            taskManager.tell(new TriggerStackTraceSample(1337, tdd.getExecutionAttemptId(), numSamples, Time.milliseconds(100L), maxDepth), testActorGateway);
                            // Receive the expected message (heartbeat races possible)
                            Object[] msg = receiveN(1);
                            while (!(msg[0] instanceof StackTraceSampleResponse)) {
                                msg = receiveN(1);
                            }
                            StackTraceSampleResponse response = (StackTraceSampleResponse) msg[0];
                            // ---- Verify response ----
                            assertEquals(1337, response.getSampleId());
                            assertEquals(tdd.getExecutionAttemptId(), response.getExecutionAttemptID());
                            List<StackTraceElement[]> traces = response.getSamples();
                            assertEquals("Number of samples", numSamples, traces.size());
                            for (StackTraceElement[] trace : traces) {
                                assertEquals("Max depth", maxDepth, trace.length);
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            fail(e.getMessage());
                        }
                    }
                };
                //
                // 4) Trigger sample for the blocking task, but cancel it during sampling
                //
                new Within(d) {

                    @Override
                    protected void run() {
                        try {
                            int maxAttempts = 10;
                            int sleepTime = 100;
                            for (int i = 0; i < maxAttempts; i++, sleepTime *= 2) {
                                // Trigger many samples in order to cancel the task
                                // during a sample
                                taskManager.tell(new TriggerStackTraceSample(44, tdd.getExecutionAttemptId(), Integer.MAX_VALUE, Time.milliseconds(10L), 0), testActorGateway);
                                Thread.sleep(sleepTime);
                                Future<?> removeFuture = taskManager.ask(new TestingJobManagerMessages.NotifyWhenJobRemoved(jobId), remaining());
                                // Cancel the task
                                taskManager.tell(new CancelTask(tdd.getExecutionAttemptId()));
                                // Receive the expected message (heartbeat races possible)
                                while (true) {
                                    Object[] msg = receiveN(1);
                                    if (msg[0] instanceof StackTraceSampleResponse) {
                                        StackTraceSampleResponse response = (StackTraceSampleResponse) msg[0];
                                        assertEquals(tdd.getExecutionAttemptId(), response.getExecutionAttemptID());
                                        assertEquals(44, response.getSampleId());
                                        // Done
                                        return;
                                    } else if (msg[0] instanceof Failure) {
                                        // Wait for removal before resubmitting
                                        Await.ready(removeFuture, remaining());
                                        Future<?> taskRunningFuture = taskManager.ask(new TestingTaskManagerMessages.NotifyWhenTaskIsRunning(tdd.getExecutionAttemptId()), timeout);
                                        // Resubmit
                                        taskManager.tell(new SubmitTask(tdd));
                                        Await.ready(taskRunningFuture, remaining());
                                        // Retry the sample message
                                        break;
                                    } else {
                                        // Different message
                                        continue;
                                    }
                                }
                            }
                        } catch (Exception e) {
                            e.printStackTrace();
                            fail(e.getMessage());
                        }
                    }
                };
            } finally {
                TestingUtils.stopActor(taskManagerActorGateway);
                TestingUtils.stopActor(jobManagerActorGateway);
            }
        }
    };
}

Example 2 with Future

use of scala.concurrent.Future in project flink by apache.

the class QueryableStateClientTest method testIntegrationWithKvStateServer.

/**
	 * Tests queries against multiple servers.
	 *
	 * <p>The servers are populated with different keys and the client queries
	 * all available keys from all servers.
	 */
@Test
public void testIntegrationWithKvStateServer() throws Exception {
    // Config
    int numServers = 2;
    int numKeys = 1024;
    int numKeyGroups = 1;
    JobID jobId = new JobID();
    JobVertexID jobVertexId = new JobVertexID();
    KvStateServer[] servers = new KvStateServer[numServers];
    AtomicKvStateRequestStats[] serverStats = new AtomicKvStateRequestStats[numServers];
    QueryableStateClient client = null;
    KvStateClient networkClient = null;
    AtomicKvStateRequestStats networkClientStats = new AtomicKvStateRequestStats();
    MemoryStateBackend backend = new MemoryStateBackend();
    DummyEnvironment dummyEnv = new DummyEnvironment("test", 1, 0);
    AbstractKeyedStateBackend<Integer> keyedStateBackend = backend.createKeyedStateBackend(dummyEnv, new JobID(), "test_op", IntSerializer.INSTANCE, numKeyGroups, new KeyGroupRange(0, 0), new KvStateRegistry().createTaskRegistry(new JobID(), new JobVertexID()));
    try {
        KvStateRegistry[] registries = new KvStateRegistry[numServers];
        KvStateID[] kvStateIds = new KvStateID[numServers];
        List<HeapValueState<Integer, VoidNamespace, Integer>> kvStates = new ArrayList<>();
        // Start the servers
        for (int i = 0; i < numServers; i++) {
            registries[i] = new KvStateRegistry();
            serverStats[i] = new AtomicKvStateRequestStats();
            servers[i] = new KvStateServer(InetAddress.getLocalHost(), 0, 1, 1, registries[i], serverStats[i]);
            servers[i].start();
            ValueStateDescriptor<Integer> descriptor = new ValueStateDescriptor<>("any", IntSerializer.INSTANCE);
            RegisteredBackendStateMetaInfo<VoidNamespace, Integer> registeredBackendStateMetaInfo = new RegisteredBackendStateMetaInfo<>(descriptor.getType(), descriptor.getName(), VoidNamespaceSerializer.INSTANCE, IntSerializer.INSTANCE);
            // Register state
            HeapValueState<Integer, VoidNamespace, Integer> kvState = new HeapValueState<>(descriptor, new NestedMapsStateTable<Integer, VoidNamespace, Integer>(keyedStateBackend, registeredBackendStateMetaInfo), IntSerializer.INSTANCE, VoidNamespaceSerializer.INSTANCE);
            kvStates.add(kvState);
            kvStateIds[i] = registries[i].registerKvState(jobId, new JobVertexID(), new KeyGroupRange(i, i), "choco", kvState);
        }
        int[] expectedRequests = new int[numServers];
        for (int key = 0; key < numKeys; key++) {
            int targetKeyGroupIndex = MathUtils.murmurHash(key) % numServers;
            expectedRequests[targetKeyGroupIndex]++;
            HeapValueState<Integer, VoidNamespace, Integer> kvState = kvStates.get(targetKeyGroupIndex);
            keyedStateBackend.setCurrentKey(key);
            kvState.setCurrentNamespace(VoidNamespace.INSTANCE);
            kvState.update(1337 + key);
        }
        // Location lookup service
        KvStateLocation location = new KvStateLocation(jobId, jobVertexId, numServers, "choco");
        for (int keyGroupIndex = 0; keyGroupIndex < numServers; keyGroupIndex++) {
            location.registerKvState(new KeyGroupRange(keyGroupIndex, keyGroupIndex), kvStateIds[keyGroupIndex], servers[keyGroupIndex].getAddress());
        }
        KvStateLocationLookupService lookupService = mock(KvStateLocationLookupService.class);
        when(lookupService.getKvStateLookupInfo(eq(jobId), eq("choco"))).thenReturn(Futures.successful(location));
        // The client
        networkClient = new KvStateClient(1, networkClientStats);
        client = new QueryableStateClient(lookupService, networkClient, testActorSystem.dispatcher());
        // Send all queries
        List<Future<byte[]>> futures = new ArrayList<>(numKeys);
        for (int key = 0; key < numKeys; key++) {
            byte[] serializedKeyAndNamespace = KvStateRequestSerializer.serializeKeyAndNamespace(key, IntSerializer.INSTANCE, VoidNamespace.INSTANCE, VoidNamespaceSerializer.INSTANCE);
            futures.add(client.getKvState(jobId, "choco", key, serializedKeyAndNamespace));
        }
        // Verify results
        Future<Iterable<byte[]>> future = Futures.sequence(futures, testActorSystem.dispatcher());
        Iterable<byte[]> results = Await.result(future, timeout);
        int index = 0;
        for (byte[] buffer : results) {
            int deserializedValue = KvStateRequestSerializer.deserializeValue(buffer, IntSerializer.INSTANCE);
            assertEquals(1337 + index, deserializedValue);
            index++;
        }
        // Verify requests
        for (int i = 0; i < numServers; i++) {
            int numRetries = 10;
            for (int retry = 0; retry < numRetries; retry++) {
                try {
                    assertEquals("Unexpected number of requests", expectedRequests[i], serverStats[i].getNumRequests());
                    assertEquals("Unexpected success requests", expectedRequests[i], serverStats[i].getNumSuccessful());
                    assertEquals("Unexpected failed requests", 0, serverStats[i].getNumFailed());
                    break;
                } catch (Throwable t) {
                    // Retry
                    if (retry == numRetries - 1) {
                        throw t;
                    } else {
                        Thread.sleep(100);
                    }
                }
            }
        }
    } finally {
        if (client != null) {
            client.shutDown();
        }
        if (networkClient != null) {
            networkClient.shutDown();
        }
        for (KvStateServer server : servers) {
            if (server != null) {
                server.shutDown();
            }
        }
    }
}

Example 3 with Future

use of scala.concurrent.Future in project flink by apache.

the class KvStateClientTest method testClientServerIntegration.

/**
	 * Tests multiple clients querying multiple servers until 100k queries have
	 * been processed. At this point, the client is shut down and its verified
	 * that all ongoing requests are failed.
	 */
@Test
public void testClientServerIntegration() throws Exception {
    // Config
    final int numServers = 2;
    final int numServerEventLoopThreads = 2;
    final int numServerQueryThreads = 2;
    final int numClientEventLoopThreads = 4;
    final int numClientsTasks = 8;
    final int batchSize = 16;
    final int numKeyGroups = 1;
    AbstractStateBackend abstractBackend = new MemoryStateBackend();
    KvStateRegistry dummyRegistry = new KvStateRegistry();
    DummyEnvironment dummyEnv = new DummyEnvironment("test", 1, 0);
    dummyEnv.setKvStateRegistry(dummyRegistry);
    AbstractKeyedStateBackend<Integer> backend = abstractBackend.createKeyedStateBackend(dummyEnv, new JobID(), "test_op", IntSerializer.INSTANCE, numKeyGroups, new KeyGroupRange(0, 0), dummyRegistry.createTaskRegistry(new JobID(), new JobVertexID()));
    final FiniteDuration timeout = new FiniteDuration(10, TimeUnit.SECONDS);
    AtomicKvStateRequestStats clientStats = new AtomicKvStateRequestStats();
    KvStateClient client = null;
    ExecutorService clientTaskExecutor = null;
    final KvStateServer[] server = new KvStateServer[numServers];
    try {
        client = new KvStateClient(numClientEventLoopThreads, clientStats);
        clientTaskExecutor = Executors.newFixedThreadPool(numClientsTasks);
        // Create state
        ValueStateDescriptor<Integer> desc = new ValueStateDescriptor<>("any", IntSerializer.INSTANCE);
        desc.setQueryable("any");
        // Create servers
        KvStateRegistry[] registry = new KvStateRegistry[numServers];
        AtomicKvStateRequestStats[] serverStats = new AtomicKvStateRequestStats[numServers];
        final KvStateID[] ids = new KvStateID[numServers];
        for (int i = 0; i < numServers; i++) {
            registry[i] = new KvStateRegistry();
            serverStats[i] = new AtomicKvStateRequestStats();
            server[i] = new KvStateServer(InetAddress.getLocalHost(), 0, numServerEventLoopThreads, numServerQueryThreads, registry[i], serverStats[i]);
            server[i].start();
            backend.setCurrentKey(1010 + i);
            // Value per server
            ValueState<Integer> state = backend.getPartitionedState(VoidNamespace.INSTANCE, VoidNamespaceSerializer.INSTANCE, desc);
            state.update(201 + i);
            // we know it must be a KvStat but this is not exposed to the user via State
            InternalKvState<?> kvState = (InternalKvState<?>) state;
            // Register KvState (one state instance for all server)
            ids[i] = registry[i].registerKvState(new JobID(), new JobVertexID(), new KeyGroupRange(0, 0), "any", kvState);
        }
        final KvStateClient finalClient = client;
        Callable<Void> queryTask = new Callable<Void>() {

            @Override
            public Void call() throws Exception {
                while (true) {
                    if (Thread.interrupted()) {
                        throw new InterruptedException();
                    }
                    // Random server permutation
                    List<Integer> random = new ArrayList<>();
                    for (int j = 0; j < batchSize; j++) {
                        random.add(j);
                    }
                    Collections.shuffle(random);
                    // Dispatch queries
                    List<Future<byte[]>> futures = new ArrayList<>(batchSize);
                    for (int j = 0; j < batchSize; j++) {
                        int targetServer = random.get(j) % numServers;
                        byte[] serializedKeyAndNamespace = KvStateRequestSerializer.serializeKeyAndNamespace(1010 + targetServer, IntSerializer.INSTANCE, VoidNamespace.INSTANCE, VoidNamespaceSerializer.INSTANCE);
                        futures.add(finalClient.getKvState(server[targetServer].getAddress(), ids[targetServer], serializedKeyAndNamespace));
                    }
                    // Verify results
                    for (int j = 0; j < batchSize; j++) {
                        int targetServer = random.get(j) % numServers;
                        Future<byte[]> future = futures.get(j);
                        byte[] buf = Await.result(future, timeout);
                        int value = KvStateRequestSerializer.deserializeValue(buf, IntSerializer.INSTANCE);
                        assertEquals(201 + targetServer, value);
                    }
                }
            }
        };
        // Submit tasks
        List<java.util.concurrent.Future<Void>> taskFutures = new ArrayList<>();
        for (int i = 0; i < numClientsTasks; i++) {
            taskFutures.add(clientTaskExecutor.submit(queryTask));
        }
        long numRequests;
        while ((numRequests = clientStats.getNumRequests()) < 100_000) {
            Thread.sleep(100);
            LOG.info("Number of requests {}/100_000", numRequests);
        }
        // Shut down
        client.shutDown();
        for (java.util.concurrent.Future<Void> future : taskFutures) {
            try {
                future.get();
                fail("Did not throw expected Exception after shut down");
            } catch (ExecutionException t) {
                if (t.getCause() instanceof ClosedChannelException || t.getCause() instanceof IllegalStateException) {
                // Expected
                } else {
                    t.printStackTrace();
                    fail("Failed with unexpected Exception type: " + t.getClass().getName());
                }
            }
        }
        assertEquals("Connection leak (client)", 0, clientStats.getNumConnections());
        for (int i = 0; i < numServers; i++) {
            boolean success = false;
            int numRetries = 0;
            while (!success) {
                try {
                    assertEquals("Connection leak (server)", 0, serverStats[i].getNumConnections());
                    success = true;
                } catch (Throwable t) {
                    if (numRetries < 10) {
                        LOG.info("Retrying connection leak check (server)");
                        Thread.sleep((numRetries + 1) * 50);
                        numRetries++;
                    } else {
                        throw t;
                    }
                }
            }
        }
    } finally {
        if (client != null) {
            client.shutDown();
        }
        for (int i = 0; i < numServers; i++) {
            if (server[i] != null) {
                server[i].shutDown();
            }
        }
        if (clientTaskExecutor != null) {
            clientTaskExecutor.shutdown();
        }
    }
}

Example 4 with Future

use of scala.concurrent.Future in project flink by apache.

the class KvStateClientTest method testConcurrentQueries.

/**
	 * Multiple threads concurrently fire queries.
	 */
@Test
public void testConcurrentQueries() throws Exception {
    Deadline deadline = TEST_TIMEOUT.fromNow();
    AtomicKvStateRequestStats stats = new AtomicKvStateRequestStats();
    ExecutorService executor = null;
    KvStateClient client = null;
    Channel serverChannel = null;
    final byte[] serializedResult = new byte[1024];
    ThreadLocalRandom.current().nextBytes(serializedResult);
    try {
        int numQueryTasks = 4;
        final int numQueriesPerTask = 1024;
        executor = Executors.newFixedThreadPool(numQueryTasks);
        client = new KvStateClient(1, stats);
        serverChannel = createServerChannel(new ChannelInboundHandlerAdapter() {

            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                ByteBuf buf = (ByteBuf) msg;
                assertEquals(KvStateRequestType.REQUEST, KvStateRequestSerializer.deserializeHeader(buf));
                KvStateRequest request = KvStateRequestSerializer.deserializeKvStateRequest(buf);
                buf.release();
                ByteBuf response = KvStateRequestSerializer.serializeKvStateRequestResult(ctx.alloc(), request.getRequestId(), serializedResult);
                ctx.channel().writeAndFlush(response);
            }
        });
        final KvStateServerAddress serverAddress = getKvStateServerAddress(serverChannel);
        final KvStateClient finalClient = client;
        Callable<List<Future<byte[]>>> queryTask = new Callable<List<Future<byte[]>>>() {

            @Override
            public List<Future<byte[]>> call() throws Exception {
                List<Future<byte[]>> results = new ArrayList<>(numQueriesPerTask);
                for (int i = 0; i < numQueriesPerTask; i++) {
                    results.add(finalClient.getKvState(serverAddress, new KvStateID(), new byte[0]));
                }
                return results;
            }
        };
        // Submit query tasks
        List<java.util.concurrent.Future<List<Future<byte[]>>>> futures = new ArrayList<>();
        for (int i = 0; i < numQueryTasks; i++) {
            futures.add(executor.submit(queryTask));
        }
        // Verify results
        for (java.util.concurrent.Future<List<Future<byte[]>>> future : futures) {
            List<Future<byte[]>> results = future.get(deadline.timeLeft().toMillis(), TimeUnit.MILLISECONDS);
            for (Future<byte[]> result : results) {
                byte[] actual = Await.result(result, deadline.timeLeft());
                assertArrayEquals(serializedResult, actual);
            }
        }
        int totalQueries = numQueryTasks * numQueriesPerTask;
        // Counts can take some time to propagate
        while (deadline.hasTimeLeft() && stats.getNumSuccessful() != totalQueries) {
            Thread.sleep(100);
        }
        assertEquals(totalQueries, stats.getNumRequests());
        assertEquals(totalQueries, stats.getNumSuccessful());
    } finally {
        if (executor != null) {
            executor.shutdown();
        }
        if (serverChannel != null) {
            serverChannel.close();
        }
        if (client != null) {
            client.shutDown();
        }
        assertEquals("Channel leak", 0, stats.getNumConnections());
    }
}

Example 5 with Future

use of scala.concurrent.Future in project flink by apache.

the class KvStateClientTest method testSimpleRequests.

/**
	 * Tests simple queries, of which half succeed and half fail.
	 */
@Test
public void testSimpleRequests() throws Exception {
    Deadline deadline = TEST_TIMEOUT.fromNow();
    AtomicKvStateRequestStats stats = new AtomicKvStateRequestStats();
    KvStateClient client = null;
    Channel serverChannel = null;
    try {
        client = new KvStateClient(1, stats);
        // Random result
        final byte[] expected = new byte[1024];
        ThreadLocalRandom.current().nextBytes(expected);
        final LinkedBlockingQueue<ByteBuf> received = new LinkedBlockingQueue<>();
        final AtomicReference<Channel> channel = new AtomicReference<>();
        serverChannel = createServerChannel(new ChannelInboundHandlerAdapter() {

            @Override
            public void channelActive(ChannelHandlerContext ctx) throws Exception {
                channel.set(ctx.channel());
            }

            @Override
            public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
                received.add((ByteBuf) msg);
            }
        });
        KvStateServerAddress serverAddress = getKvStateServerAddress(serverChannel);
        List<Future<byte[]>> futures = new ArrayList<>();
        int numQueries = 1024;
        for (int i = 0; i < numQueries; i++) {
            futures.add(client.getKvState(serverAddress, new KvStateID(), new byte[0]));
        }
        // Respond to messages
        Exception testException = new RuntimeException("Expected test Exception");
        for (int i = 0; i < numQueries; i++) {
            ByteBuf buf = received.poll(deadline.timeLeft().toMillis(), TimeUnit.MILLISECONDS);
            assertNotNull("Receive timed out", buf);
            Channel ch = channel.get();
            assertNotNull("Channel not active", ch);
            assertEquals(KvStateRequestType.REQUEST, KvStateRequestSerializer.deserializeHeader(buf));
            KvStateRequest request = KvStateRequestSerializer.deserializeKvStateRequest(buf);
            buf.release();
            if (i % 2 == 0) {
                ByteBuf response = KvStateRequestSerializer.serializeKvStateRequestResult(serverChannel.alloc(), request.getRequestId(), expected);
                ch.writeAndFlush(response);
            } else {
                ByteBuf response = KvStateRequestSerializer.serializeKvStateRequestFailure(serverChannel.alloc(), request.getRequestId(), testException);
                ch.writeAndFlush(response);
            }
        }
        for (int i = 0; i < numQueries; i++) {
            if (i % 2 == 0) {
                byte[] serializedResult = Await.result(futures.get(i), deadline.timeLeft());
                assertArrayEquals(expected, serializedResult);
            } else {
                try {
                    Await.result(futures.get(i), deadline.timeLeft());
                    fail("Did not throw expected Exception");
                } catch (RuntimeException ignored) {
                // Expected
                }
            }
        }
        assertEquals(numQueries, stats.getNumRequests());
        int expectedRequests = numQueries / 2;
        // Counts can take some time to propagate
        while (deadline.hasTimeLeft() && (stats.getNumSuccessful() != expectedRequests || stats.getNumFailed() != expectedRequests)) {
            Thread.sleep(100);
        }
        assertEquals(expectedRequests, stats.getNumSuccessful());
        assertEquals(expectedRequests, stats.getNumFailed());
    } finally {
        if (client != null) {
            client.shutDown();
        }
        if (serverChannel != null) {
            serverChannel.close();
        }
        assertEquals("Channel leak", 0, stats.getNumConnections());
    }
}