Merge f660b15e52 into 4a5aa37169

It moves the `ReconfigurableQuorumIntegrationTest` class to the
`org.apache.kafka.server` package and consolidates two related tests,
`RemoveAndAddVoterWithValidClusterId` and
`RemoveAndAddVoterWithInconsistentClusterId`, into a single file. This
improves code organization and reduces redundancy.

Reviewers: Chia-Ping Tsai <chia7712@gmail.com>

clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/admin/ReconfigurableQuorumIntegrationTest.java

@@ -1,132 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements. See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.kafka.clients.admin;
-
-import org.apache.kafka.common.Uuid;
-import org.apache.kafka.common.errors.InconsistentClusterIdException;
-import org.apache.kafka.common.test.KafkaClusterTestKit;
-import org.apache.kafka.common.test.TestKitNodes;
-import org.apache.kafka.test.TestUtils;
-
-import org.junit.jupiter.api.Tag;
-import org.junit.jupiter.api.Test;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
-import java.util.concurrent.ExecutionException;
-import java.util.stream.Collectors;
-
-import static org.junit.jupiter.api.Assertions.assertEquals;
-
-@Tag("integration")
-public class ReconfigurableQuorumIntegrationTest {
-
-    static Map<Integer, Uuid> descVoterDirs(Admin admin) throws ExecutionException, InterruptedException {
-        var quorumInfo = admin.describeMetadataQuorum().quorumInfo().get();
-        return quorumInfo.voters().stream().collect(Collectors.toMap(QuorumInfo.ReplicaState::replicaId, QuorumInfo.ReplicaState::replicaDirectoryId));
-    }
-
-    @Test
-    public void testRemoveAndAddVoterWithValidClusterId() throws Exception {
-        final var nodes = new TestKitNodes.Builder()
-                .setClusterId("test-cluster")
-                .setNumBrokerNodes(1)
-                .setNumControllerNodes(3)
-                .build();
-
-        final Map<Integer, Uuid> initialVoters = new HashMap<>();
-        for (final var controllerNode : nodes.controllerNodes().values()) {
-            initialVoters.put(
-                    controllerNode.id(),
-                    controllerNode.metadataDirectoryId()
-            );
-        }
-
-        try (var cluster = new KafkaClusterTestKit.Builder(nodes).setInitialVoterSet(initialVoters).build()) {
-            cluster.format();
-            cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
-                TestUtils.waitForCondition(() -> {
-                    Map<Integer, Uuid> voters = descVoterDirs(admin);
-                    assertEquals(Set.of(3000, 3001, 3002), voters.keySet());
-                    return voters.values().stream().noneMatch(directory -> directory.equals(Uuid.ZERO_UUID));
-                }, "Initial quorum voters should be {3000, 3001, 3002} and all should have non-zero directory IDs");
-
-                Uuid dirId = cluster.nodes().controllerNodes().get(3000).metadataDirectoryId();
-                admin.removeRaftVoter(
-                        3000,
-                        dirId,
-                        new RemoveRaftVoterOptions().setClusterId(Optional.of("test-cluster"))
-                ).all().get();
-                TestUtils.waitForCondition(() -> {
-                    Map<Integer, Uuid> voters = descVoterDirs(admin);
-                    assertEquals(Set.of(3001, 3002), voters.keySet());
-                    return voters.values().stream().noneMatch(directory -> directory.equals(Uuid.ZERO_UUID));
-                }, "After removing voter 3000, remaining voters should be {3001, 3002} with non-zero directory IDs");
-
-                admin.addRaftVoter(
-                        3000,
-                        dirId,
-                        Set.of(new RaftVoterEndpoint("CONTROLLER", "example.com", 8080)),
-                        new AddRaftVoterOptions().setClusterId(Optional.of("test-cluster"))
-                ).all().get();
-            }
-        }
-    }
-
-    @Test
-    public void testRemoveAndAddVoterWithInconsistentClusterId() throws Exception {
-        final var nodes = new TestKitNodes.Builder()
-                .setClusterId("test-cluster")
-                .setNumBrokerNodes(1)
-                .setNumControllerNodes(3)
-                .build();
-
-        final Map<Integer, Uuid> initialVoters = new HashMap<>();
-        for (final var controllerNode : nodes.controllerNodes().values()) {
-            initialVoters.put(
-                    controllerNode.id(),
-                    controllerNode.metadataDirectoryId()
-            );
-        }
-
-        try (var cluster = new KafkaClusterTestKit.Builder(nodes).setInitialVoterSet(initialVoters).build()) {
-            cluster.format();
-            cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
-                Uuid dirId = cluster.nodes().controllerNodes().get(3000).metadataDirectoryId();
-                var removeFuture = admin.removeRaftVoter(
-                        3000,
-                        dirId,
-                        new RemoveRaftVoterOptions().setClusterId(Optional.of("inconsistent"))
-                ).all();
-                TestUtils.assertFutureThrows(InconsistentClusterIdException.class, removeFuture);
-
-                var addFuture = admin.addRaftVoter(
-                        3000,
-                        dirId,
-                        Set.of(new RaftVoterEndpoint("CONTROLLER", "example.com", 8080)),
-                        new AddRaftVoterOptions().setClusterId(Optional.of("inconsistent"))
-                ).all();
-                TestUtils.assertFutureThrows(InconsistentClusterIdException.class, addFuture);
-            }
-        }
-    }
-}

clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/ConsumerIntegrationTest.java

@@ -122,7 +122,7 @@ public class ConsumerIntegrationTest {
                 }
             });
 
-            TestUtils.waitForCondition(() -> consumer.poll(Duration.ofSeconds(1)).count() == 1,
+            TestUtils.waitForCondition(() -> consumer.poll(Duration.ofMillis(100)).count() == 1,
                     5000,
                     "failed to poll data");
         }
@@ -266,10 +266,11 @@ public class ConsumerIntegrationTest {
             consumer1.subscribe(List.of(topic));
             consumer2.subscribe(List.of(topic));
 
+            Duration pollTimeout = Duration.ofMillis(100);
             TestUtils.waitForCondition(() -> {
-                consumer0.poll(Duration.ofMillis(1000));
-                consumer1.poll(Duration.ofMillis(1000));
-                consumer2.poll(Duration.ofMillis(1000));
+                consumer0.poll(pollTimeout);
+                consumer1.poll(pollTimeout);
+                consumer2.poll(pollTimeout);
                 return consumer0.assignment().equals(Set.of(new TopicPartition(topic, 0))) &&
                     consumer1.assignment().isEmpty() &&
                     consumer2.assignment().isEmpty();
@@ -284,9 +285,9 @@ public class ConsumerIntegrationTest {
             );
             clusterInstance.waitTopicCreation(topic, 3);
             TestUtils.waitForCondition(() -> {
-                consumer0.poll(Duration.ofMillis(1000));
-                consumer1.poll(Duration.ofMillis(1000));
-                consumer2.poll(Duration.ofMillis(1000));
+                consumer0.poll(pollTimeout);
+                consumer1.poll(pollTimeout);
+                consumer2.poll(pollTimeout);
                 return consumer0.assignment().equals(Set.of(new TopicPartition(topic, 0))) &&
                     consumer1.assignment().equals(Set.of(new TopicPartition(topic, 1), new TopicPartition(topic, 2))) &&
                     consumer2.assignment().isEmpty();
@@ -301,9 +302,9 @@ public class ConsumerIntegrationTest {
             );
             clusterInstance.waitTopicCreation(topic, 6);
             TestUtils.waitForCondition(() -> {
-                consumer0.poll(Duration.ofMillis(1000));
-                consumer1.poll(Duration.ofMillis(1000));
-                consumer2.poll(Duration.ofMillis(1000));
+                consumer0.poll(pollTimeout);
+                consumer1.poll(pollTimeout);
+                consumer2.poll(pollTimeout);
                 return consumer0.assignment().equals(Set.of(new TopicPartition(topic, 0))) &&
                     consumer1.assignment().equals(Set.of(new TopicPartition(topic, 1), new TopicPartition(topic, 2))) &&
                     consumer2.assignment().equals(Set.of(new TopicPartition(topic, 3), new TopicPartition(topic, 4), new TopicPartition(topic, 5)));
@@ -325,9 +326,9 @@ public class ConsumerIntegrationTest {
                 new TopicPartition(topic, 5), Optional.of(new NewPartitionReassignment(List.of(0)))
             )).all().get();
             TestUtils.waitForCondition(() -> {
-                consumer0.poll(Duration.ofMillis(1000));
-                consumer1.poll(Duration.ofMillis(1000));
-                consumer2.poll(Duration.ofMillis(1000));
+                consumer0.poll(pollTimeout);
+                consumer1.poll(pollTimeout);
+                consumer2.poll(pollTimeout);
                 return consumer0.assignment().equals(Set.of(new TopicPartition(topic, 5))) &&
                     consumer1.assignment().equals(Set.of(new TopicPartition(topic, 3), new TopicPartition(topic, 4))) &&
                     consumer2.assignment().equals(Set.of(new TopicPartition(topic, 0), new TopicPartition(topic, 1), new TopicPartition(topic, 2)));

clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/PlaintextConsumerCommitTest.java

@@ -283,11 +283,13 @@ public class PlaintextConsumerCommitTest {
             // In both CLASSIC and CONSUMER protocols, interceptors are executed in poll and close.
             // However, in the CONSUMER protocol, the assignment may be changed outside a poll, so
             // we need to poll once to ensure the interceptor is called.
-            if (groupProtocol == GroupProtocol.CONSUMER) {
-                consumer.poll(Duration.ZERO);
-            }
-
-            assertTrue(MockConsumerInterceptor.ON_COMMIT_COUNT.intValue() > commitCountBeforeRebalance);
+            TestUtils.waitForCondition(
+                () -> {
+                    consumer.poll(Duration.ZERO);
+                    return MockConsumerInterceptor.ON_COMMIT_COUNT.intValue() > commitCountBeforeRebalance;
+                },
+                "Consumer.poll() did not invoke onCommit() before timeout elapse"
+            );
 
             // verify commits are intercepted on close
             var commitCountBeforeClose = MockConsumerInterceptor.ON_COMMIT_COUNT.intValue();

clients/clients-integration-tests/src/test/java/org/apache/kafka/clients/consumer/PlaintextConsumerTest.java

@@ -66,7 +66,6 @@ import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.IntStream;
 
 import static org.apache.kafka.clients.ClientsTestUtils.BaseConsumerTestcase.BROKER_COUNT;
@@ -810,7 +809,7 @@ public class PlaintextConsumerTest {
             // Create a consumer and consumer some messages.
             var listener = new TestConsumerReassignmentListener();
             consumer.subscribe(List.of(TOPIC, topic2), listener);
-            var records = awaitNonEmptyRecords(consumer, TP);
+            var records = ConsumerPollTestUtils.waitForRecords(consumer);
             assertEquals(1, listener.callsToAssigned, "should be assigned once");
 
             // Verify the metric exist.
@@ -877,7 +876,7 @@ public class PlaintextConsumerTest {
             // Create a consumer and consumer some messages.
             var listener = new TestConsumerReassignmentListener();
             consumer.subscribe(List.of(TOPIC, topic2), listener);
-            var records = awaitNonEmptyRecords(consumer, TP);
+            var records = ConsumerPollTestUtils.waitForRecords(consumer);
             assertEquals(1, listener.callsToAssigned, "should be assigned once");
 
             // Verify the metric exist.
@@ -944,7 +943,7 @@ public class PlaintextConsumerTest {
             sendRecords(producer, tp2, numMessages, System.currentTimeMillis());
             
             consumer.assign(List.of(TP));
-            var records = awaitNonEmptyRecords(consumer, TP);
+            var records = ConsumerPollTestUtils.waitForRecords(consumer);
 
             // Verify the metric exist.
             Map<String, String> tags = Map.of(
@@ -958,7 +957,7 @@ public class PlaintextConsumerTest {
             assertEquals((double) records.count(), fetchLead.metricValue(), "The lead should be " + records.count());
 
             consumer.assign(List.of(tp2));
-            awaitNonEmptyRecords(consumer, tp2);
+            ConsumerPollTestUtils.waitForRecords(consumer);
             assertNull(consumer.metrics().get(new MetricName("records-lead", "consumer-fetch-manager-metrics", "", tags)));
         }
     }
@@ -999,7 +998,7 @@ public class PlaintextConsumerTest {
             sendRecords(producer, tp2, numMessages, System.currentTimeMillis());
 
             consumer.assign(List.of(TP));
-            var records = awaitNonEmptyRecords(consumer, TP);
+            var records = ConsumerPollTestUtils.waitForRecords(consumer);
 
             // Verify the metric exist.
             Map<String, String> tags = Map.of(
@@ -1014,7 +1013,7 @@ public class PlaintextConsumerTest {
             var expectedLag = numMessages - records.count();
             assertEquals(expectedLag, (double) fetchLag.metricValue(), EPSILON, "The lag should be " + expectedLag);
             consumer.assign(List.of(tp2));
-            awaitNonEmptyRecords(consumer, tp2);
+            ConsumerPollTestUtils.waitForRecords(consumer);
             assertNull(consumer.metrics().get(new MetricName(TP + ".records-lag", "consumer-fetch-manager-metrics", "", tags)));
             assertNull(consumer.metrics().get(new MetricName("records-lag", "consumer-fetch-manager-metrics", "", tags)));
         }
@@ -1058,7 +1057,7 @@ public class PlaintextConsumerTest {
             sendRecords(producer, tp2, numMessages, System.currentTimeMillis());
 
             consumer.assign(List.of(TP));
-            awaitNonEmptyRecords(consumer, TP);
+            ConsumerPollTestUtils.waitForRecords(consumer);
 
             // Verify the metric exist.
             Map<String, String> tags = Map.of(
@@ -1203,12 +1202,21 @@ public class PlaintextConsumerTest {
             consumer3.assign(List.of(TP));
             consumer3.seek(TP, 1);
 
-            var numRecords1 = consumer1.poll(Duration.ofMillis(5000)).count();
+            TestUtils.waitForCondition(
+                () -> consumer1.poll(Duration.ofMillis(5000)).count() == 3,
+                "consumer1 did not consume from earliest offset"
+            );
             assertThrows(InvalidGroupIdException.class, consumer1::commitSync);
             assertThrows(InvalidGroupIdException.class, () -> consumer2.committed(Set.of(TP)));
 
-            var numRecords2 = consumer2.poll(Duration.ofMillis(5000)).count();
-            var numRecords3 = consumer3.poll(Duration.ofMillis(5000)).count();
+            TestUtils.waitForCondition(
+                () -> consumer2.poll(Duration.ofMillis(5000)).count() == 0,
+                "Expected consumer2 to consume from latest offset"
+            );
+            TestUtils.waitForCondition(
+                () -> consumer3.poll(Duration.ofMillis(5000)).count() == 2,
+                "Expected consumer3 to consume from offset 1"
+            );
 
             consumer1.unsubscribe();
             consumer2.unsubscribe();
@@ -1217,14 +1225,6 @@ public class PlaintextConsumerTest {
             assertTrue(consumer1.assignment().isEmpty());
             assertTrue(consumer2.assignment().isEmpty());
             assertTrue(consumer3.assignment().isEmpty());
-
-            consumer1.close();
-            consumer2.close();
-            consumer3.close();
-
-            assertEquals(3, numRecords1, "Expected consumer1 to consume from earliest offset");
-            assertEquals(0, numRecords2, "Expected consumer2 to consume from latest offset");
-            assertEquals(2, numRecords3, "Expected consumer3 to consume from offset 1");
         }
     }
 
@@ -1654,7 +1654,7 @@ public class PlaintextConsumerTest {
                 consumer.subscribe(List.of(testTopic));
 
                 // This is here to allow the consumer time to settle the group membership/assignment.
-                awaitNonEmptyRecords(consumer, new TopicPartition(testTopic, 0));
+                ConsumerPollTestUtils.waitForRecords(consumer);
 
                 // Keep track of the last time the poll is invoked to ensure the deltas between invocations don't
                 // exceed the delay threshold defined above.
@@ -1674,24 +1674,6 @@ public class PlaintextConsumerTest {
         }
     }
 
-    private ConsumerRecords<byte[], byte[]> awaitNonEmptyRecords(
-        Consumer<byte[], byte[]> consumer,
-        TopicPartition tp
-    ) throws Exception {
-        AtomicReference<ConsumerRecords<byte[], byte[]>> result = new AtomicReference<>();
-
-        TestUtils.waitForCondition(() -> {
-            var polledRecords = consumer.poll(Duration.ofSeconds(10));
-            boolean hasRecords = !polledRecords.isEmpty();
-            if (hasRecords) {
-                result.set(polledRecords);
-            }
-            return hasRecords;
-        }, "Timed out waiting for non-empty records from topic " + tp.topic() + " partition " + tp.partition());
-
-        return result.get();
-    }
-
     public static class SerializerImpl implements Serializer<byte[]> {
         private final ByteArraySerializer serializer = new ByteArraySerializer();
 

clients/src/main/java/org/apache/kafka/clients/consumer/internals/AsyncKafkaConsumer.java

@@ -41,6 +41,7 @@ import org.apache.kafka.clients.consumer.internals.events.ApplicationEventHandle
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventProcessor;
 import org.apache.kafka.clients.consumer.internals.events.AssignmentChangeEvent;
 import org.apache.kafka.clients.consumer.internals.events.AsyncCommitEvent;
+import org.apache.kafka.clients.consumer.internals.events.AsyncPollEvent;
 import org.apache.kafka.clients.consumer.internals.events.BackgroundEvent;
 import org.apache.kafka.clients.consumer.internals.events.BackgroundEventHandler;
 import org.apache.kafka.clients.consumer.internals.events.CheckAndUpdatePositionsEvent;
@@ -59,7 +60,6 @@ import org.apache.kafka.clients.consumer.internals.events.FetchCommittedOffsetsE
 import org.apache.kafka.clients.consumer.internals.events.LeaveGroupOnCloseEvent;
 import org.apache.kafka.clients.consumer.internals.events.ListOffsetsEvent;
 import org.apache.kafka.clients.consumer.internals.events.PausePartitionsEvent;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ResetOffsetEvent;
 import org.apache.kafka.clients.consumer.internals.events.ResumePartitionsEvent;
 import org.apache.kafka.clients.consumer.internals.events.SeekUnvalidatedEvent;
@@ -325,8 +325,7 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
     // Init value is needed to avoid NPE in case of exception raised in the constructor
     private Optional<ClientTelemetryReporter> clientTelemetryReporter = Optional.empty();
 
-    // to keep from repeatedly scanning subscriptions in poll(), cache the result during metadata updates
-    private boolean cachedSubscriptionHasAllFetchPositions;
+    private AsyncPollEvent inflightPoll;
     private final WakeupTrigger wakeupTrigger = new WakeupTrigger();
     private final OffsetCommitCallbackInvoker offsetCommitCallbackInvoker;
     private final ConsumerRebalanceListenerInvoker rebalanceListenerInvoker;
@@ -464,7 +463,8 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
             final Supplier<ApplicationEventProcessor> applicationEventProcessorSupplier = ApplicationEventProcessor.supplier(logContext,
                     metadata,
                     subscriptions,
-                    requestManagersSupplier);
+                    requestManagersSupplier
+            );
             this.applicationEventHandler = applicationEventHandlerFactory.build(
                     logContext,
                     time,
@@ -623,7 +623,7 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
             new RebalanceCallbackMetricsManager(metrics)
         );
         ApiVersions apiVersions = new ApiVersions();
-        Supplier<NetworkClientDelegate> networkClientDelegateSupplier = () -> new NetworkClientDelegate(
+        Supplier<NetworkClientDelegate> networkClientDelegateSupplier = NetworkClientDelegate.supplier(
             time,
             config,
             logContext,
@@ -833,22 +833,13 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
             }
 
             do {
-                PollEvent event = new PollEvent(timer.currentTimeMs());
-                // Make sure to let the background thread know that we are still polling.
-                // This will trigger async auto-commits of consumed positions when hitting
-                // the interval time or reconciling new assignments
-                applicationEventHandler.add(event);
-                // Wait for reconciliation and auto-commit to be triggered, to ensure all commit requests
-                // retrieve the positions to commit before proceeding with fetching new records
-                ConsumerUtils.getResult(event.reconcileAndAutoCommit(), defaultApiTimeoutMs.toMillis());
-
                 // We must not allow wake-ups between polling for fetches and returning the records.
                 // If the polled fetches are not empty the consumed position has already been updated in the polling
                 // of the fetches. A wakeup between returned fetches and returning records would lead to never
                 // returning the records in the fetches. Thus, we trigger a possible wake-up before we poll fetches.
                 wakeupTrigger.maybeTriggerWakeup();
 
-                updateAssignmentMetadataIfNeeded(timer);
+                checkInflightPoll(timer);
                 final Fetch<K, V> fetch = pollForFetches(timer);
                 if (!fetch.isEmpty()) {
                     // before returning the fetched records, we can send off the next round of fetches
@@ -876,6 +867,71 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
         }
     }
 
+    /**
+     * {@code checkInflightPoll()} manages the lifetime of the {@link AsyncPollEvent} processing. If it is
+     * called when no event is currently processing, it will start a new event processing asynchronously. A check
+     * is made during each invocation to see if the <em>inflight</em> event has completed. If it has, it will be
+     * processed accordingly.
+     */
+    public void checkInflightPoll(Timer timer) {
+        boolean newlySubmittedEvent = false;
+
+        if (inflightPoll == null) {
+            inflightPoll = new AsyncPollEvent(calculateDeadlineMs(timer), time.milliseconds());
+            newlySubmittedEvent = true;
+
+            if (log.isTraceEnabled()) {
+                log.trace(
+                    "Submitting new inflight event {} with {} remaining on timer",
+                    inflightPoll,
+                    timer.remainingMs()
+                );
+            }
+
+            applicationEventHandler.add(inflightPoll);
+        }
+
+        try {
+            // Note: this is calling user-supplied code, so make sure that any errors thrown here are caught and
+            // the inflight event is cleared.
+            offsetCommitCallbackInvoker.executeCallbacks();
+            processBackgroundEvents();
+
+            if (inflightPoll.isComplete()) {
+                Optional<KafkaException> errorOpt = inflightPoll.error();
+
+                // The async poll event has completed, either successfully or not. In either case, clear out the
+                // inflight request.
+                log.trace("Inflight event {} completed, clearing", inflightPoll);
+                inflightPoll = null;
+
+                if (errorOpt.isPresent()) {
+                    throw errorOpt.get();
+                }
+            } else if (!newlySubmittedEvent) {
+                if (timer.isExpired()) {
+                    // The inflight event is expired...
+                    log.trace("Inflight event {} expired without completing, clearing", inflightPoll);
+                    inflightPoll = null;
+                } else {
+                    if (log.isTraceEnabled()) {
+                        log.trace(
+                            "Inflight event {} is incomplete with {} remaining on timer",
+                            inflightPoll,
+                            timer.remainingMs()
+                        );
+                    }
+                }
+            }
+        } catch (Throwable t) {
+            // If an exception is hit, bubble it up to the user but make sure to clear out the inflight request
+            // because the error effectively renders it complete.
+            log.debug("Inflight event {} failed due to {}, clearing", inflightPoll, String.valueOf(t));
+            inflightPoll = null;
+            throw ConsumerUtils.maybeWrapAsKafkaException(t);
+        }
+    }
+
     /**
      * Commit offsets returned on the last {@link #poll(Duration) poll()} for all the subscribed list of topics and
      * partitions.
@@ -1771,15 +1827,9 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
             return fetch;
         }
 
-        // send any new fetches (won't resend pending fetches)
-        sendFetches(timer);
-
         // We do not want to be stuck blocking in poll if we are missing some positions
         // since the offset lookup may be backing off after a failure
-
-        // NOTE: the use of cachedSubscriptionHasAllFetchPositions means we MUST call
-        // updateAssignmentMetadataIfNeeded before this method.
-        if (!cachedSubscriptionHasAllFetchPositions && pollTimeout > retryBackoffMs) {
+        if (pollTimeout > retryBackoffMs) {
             pollTimeout = retryBackoffMs;
         }
 
@@ -1809,19 +1859,9 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
      * of the {@link #fetchBuffer}, converting it to a well-formed {@link CompletedFetch}, validating that it and
      * the internal {@link SubscriptionState state} are correct, and then converting it all into a {@link Fetch}
      * for returning.
-     *
-     * <p/>
-     *
-     * This method will {@link ConsumerNetworkThread#wakeup() wake up the network thread} before returning. This is
-     * done as an optimization so that the <em>next round of data can be pre-fetched</em>.
      */
     private Fetch<K, V> collectFetch() {
-        final Fetch<K, V> fetch = fetchCollector.collectFetch(fetchBuffer);
-
-        // Notify the network thread to wake up and start the next round of fetching.
-        applicationEventHandler.wakeupNetworkThread();
-
-        return fetch;
+        return fetchCollector.collectFetch(fetchBuffer);
     }
 
     /**
@@ -1834,11 +1874,10 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
      *                                       defined
      */
     private boolean updateFetchPositions(final Timer timer) {
-        cachedSubscriptionHasAllFetchPositions = false;
         try {
             CheckAndUpdatePositionsEvent checkAndUpdatePositionsEvent = new CheckAndUpdatePositionsEvent(calculateDeadlineMs(timer));
             wakeupTrigger.setActiveTask(checkAndUpdatePositionsEvent.future());
-            cachedSubscriptionHasAllFetchPositions = applicationEventHandler.addAndGet(checkAndUpdatePositionsEvent);
+            applicationEventHandler.addAndGet(checkAndUpdatePositionsEvent);
         } catch (TimeoutException e) {
             return false;
         } finally {
@@ -1856,41 +1895,6 @@ public class AsyncKafkaConsumer<K, V> implements ConsumerDelegate<K, V> {
         return groupMetadata.get().isPresent();
     }
 
-    /**
-     * This method signals the background thread to {@link CreateFetchRequestsEvent create fetch requests}.
-     *
-     * <p/>
-     *
-     * This method takes the following steps to maintain compatibility with the {@link ClassicKafkaConsumer} method
-     * of the same name:
-     *
-     * <ul>
-     *     <li>
-     *         The method will wait for confirmation of the request creation before continuing.
-     *     </li>
-     *     <li>
-     *         The method will throw exceptions encountered during request creation to the user <b>immediately</b>.
-     *     </li>
-     *     <li>
-     *         The method will suppress {@link TimeoutException}s that occur while waiting for the confirmation.
-     *         Timeouts during request creation are a byproduct of this consumer's thread communication mechanisms.
-     *         That exception type isn't thrown in the request creation step of the {@link ClassicKafkaConsumer}.
-     *         Additionally, timeouts will not impact the logic of {@link #pollForFetches(Timer) blocking requests}
-     *         as it can handle requests that are created after the timeout.
-     *     </li>
-     * </ul>
-     *
-     * @param timer Timer used to bound how long the consumer waits for the requests to be created, which in practice
-     *              is used to avoid using {@link Long#MAX_VALUE} to wait "forever"
-     */
-    private void sendFetches(Timer timer) {
-        try {
-            applicationEventHandler.addAndGet(new CreateFetchRequestsEvent(calculateDeadlineMs(timer)));
-        } catch (TimeoutException swallow) {
-            // Can be ignored, per above comments.
-        }
-    }
-
     /**
      * This method signals the background thread to {@link CreateFetchRequestsEvent create fetch requests} for the
      * pre-fetch case, i.e. right before {@link #poll(Duration)} exits. In the pre-fetch case, the application thread

clients/src/main/java/org/apache/kafka/clients/consumer/internals/ConsumerNetworkThread.java

@@ -20,9 +20,9 @@ import org.apache.kafka.clients.KafkaClient;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventProcessor;
 import org.apache.kafka.clients.consumer.internals.events.BackgroundEvent;
-import org.apache.kafka.clients.consumer.internals.events.CompletableApplicationEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
+import org.apache.kafka.clients.consumer.internals.events.MetadataErrorNotifiableEvent;
 import org.apache.kafka.clients.consumer.internals.metrics.AsyncConsumerMetrics;
 import org.apache.kafka.common.internals.IdempotentCloser;
 import org.apache.kafka.common.requests.AbstractRequest;
@@ -40,6 +40,7 @@ import java.util.Collection;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Objects;
+import java.util.Optional;
 import java.util.concurrent.BlockingQueue;
 import java.util.function.Supplier;
 
@@ -193,10 +194,13 @@ public class ConsumerNetworkThread extends KafkaThread implements Closeable {
             try {
                 if (event instanceof CompletableEvent) {
                     applicationEventReaper.add((CompletableEvent<?>) event);
-                    // Check if there are any metadata errors and fail the CompletableEvent if an error is present.
-                    // This call is meant to handle "immediately completed events" which may not enter the awaiting state,
-                    // so metadata errors need to be checked and handled right away.
-                    maybeFailOnMetadataError(List.of((CompletableEvent<?>) event));
+                }
+                // Check if there are any metadata errors and fail the CompletableEvent if an error is present.
+                // This call is meant to handle "immediately completed events" which may not enter the awaiting state,
+                // so metadata errors need to be checked and handled right away.
+                if (event instanceof MetadataErrorNotifiableEvent) {
+                    if (maybeFailOnMetadataError(List.of(event)))
+                        continue;
                 }
                 applicationEventProcessor.process(event);
             } catch (Throwable t) {
@@ -368,18 +372,27 @@ public class ConsumerNetworkThread extends KafkaThread implements Closeable {
     /**
      * If there is a metadata error, complete all uncompleted events that require subscription metadata.
      */
-    private void maybeFailOnMetadataError(List<CompletableEvent<?>> events) {
-        List<CompletableApplicationEvent<?>> subscriptionMetadataEvent = new ArrayList<>();
+    private boolean maybeFailOnMetadataError(List<?> events) {
+        List<MetadataErrorNotifiableEvent> filteredEvents = new ArrayList<>();
 
-        for (CompletableEvent<?> ce : events) {
-            if (ce instanceof CompletableApplicationEvent && ((CompletableApplicationEvent<?>) ce).requireSubscriptionMetadata())
-                subscriptionMetadataEvent.add((CompletableApplicationEvent<?>) ce);
+        for (Object obj : events) {
+            if (obj instanceof MetadataErrorNotifiableEvent) {
+                filteredEvents.add((MetadataErrorNotifiableEvent) obj);
+            }
         }
 
-        if (subscriptionMetadataEvent.isEmpty())
-            return;
-        networkClientDelegate.getAndClearMetadataError().ifPresent(metadataError ->
-                subscriptionMetadataEvent.forEach(event -> event.future().completeExceptionally(metadataError))
-        );
+        // Don't get-and-clear the metadata error if there are no events that will be notified.
+        if (filteredEvents.isEmpty())
+            return false;
+
+        Optional<Exception> andClearMetadataError = networkClientDelegate.getAndClearMetadataError();
+
+        if (andClearMetadataError.isPresent()) {
+            Exception metadataError = andClearMetadataError.get();
+            filteredEvents.forEach(e -> e.onMetadataError(metadataError));
+            return true;
+        } else {
+            return false;
+        }
     }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/NetworkClientDelegate.java

@@ -210,6 +210,30 @@ public class NetworkClientDelegate implements AutoCloseable {
         }
         ClientRequest request = makeClientRequest(r, node, currentTimeMs);
         if (!client.ready(node, currentTimeMs)) {
+            AuthenticationException authenticationException = client.authenticationException(node);
+
+            // The client may not be ready because it hit an unrecoverable authentication error. In that case, there's
+            // no benefit from retrying, so propagate the error here.
+            if (authenticationException != null) {
+                request.callback().onComplete(
+                    new ClientResponse(
+                        request.makeHeader(
+                            request.requestBuilder().latestAllowedVersion()
+                        ),
+                        request.callback(),
+                        request.destination(),
+                        request.createdTimeMs(),
+                        currentTimeMs,
+                        true,
+                        null,
+                        authenticationException,
+                        null
+                    )
+                );
+
+                return false;
+            }
+
             // enqueue the request again if the node isn't ready yet. The request will be handled in the next iteration
             // of the event loop
             log.debug("Node is not ready, handle the request in the next event loop: node={}, request={}", node, r);
@@ -471,4 +495,33 @@ public class NetworkClientDelegate implements AutoCloseable {
             }
         };
     }
+
+    /**
+     * Creates a {@link Supplier} for deferred creation during invocation by
+     * {@link ConsumerNetworkThread}.
+     */
+    public static Supplier<NetworkClientDelegate> supplier(final Time time,
+                                                           final ConsumerConfig config,
+                                                           final LogContext logContext,
+                                                           final KafkaClient client,
+                                                           final Metadata metadata,
+                                                           final BackgroundEventHandler backgroundEventHandler,
+                                                           final boolean notifyMetadataErrorsViaErrorQueue,
+                                                           final AsyncConsumerMetrics asyncConsumerMetrics) {
+        return new CachedSupplier<>() {
+            @Override
+            protected NetworkClientDelegate create() {
+                return new NetworkClientDelegate(
+                    time,
+                    config,
+                    logContext,
+                    client,
+                    metadata,
+                    backgroundEventHandler,
+                    notifyMetadataErrorsViaErrorQueue,
+                    asyncConsumerMetrics
+                );
+            }
+        };
+    }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/OffsetCommitCallbackInvoker.java

@@ -50,6 +50,16 @@ public class OffsetCommitCallbackInvoker {
         }
     }
 
+    /**
+     * Returns the current size of the queue. Used by the background thread to determine if it needs to <i>pause</i>
+     * itself to return to the application thread for processing.
+     *
+     * @return Current size of queue
+     */
+    public int size() {
+        return callbackQueue.size();
+    }
+
     public void enqueueUserCallbackInvocation(final OffsetCommitCallback callback,
                                               final Map<TopicPartition, OffsetAndMetadata> offsets,
                                               final Exception exception) {

clients/src/main/java/org/apache/kafka/clients/consumer/internals/ShareConsumerImpl.java

@@ -38,13 +38,13 @@ import org.apache.kafka.clients.consumer.internals.events.CompletableEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
 import org.apache.kafka.clients.consumer.internals.events.ErrorEvent;
 import org.apache.kafka.clients.consumer.internals.events.EventProcessor;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgeAsyncEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgeOnCloseEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgeSyncEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgementCommitCallbackEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgementCommitCallbackRegistrationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareFetchEvent;
+import org.apache.kafka.clients.consumer.internals.events.SharePollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareSubscriptionChangeEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareUnsubscribeEvent;
 import org.apache.kafka.clients.consumer.internals.events.StopFindCoordinatorOnCloseEvent;
@@ -384,7 +384,7 @@ public class ShareConsumerImpl<K, V> implements ShareConsumerDelegate<K, V> {
             backgroundEventQueue, time, asyncConsumerMetrics);
 
         final Supplier<NetworkClientDelegate> networkClientDelegateSupplier =
-                () -> new NetworkClientDelegate(time, config, logContext, client, metadata, backgroundEventHandler, true, asyncConsumerMetrics);
+                NetworkClientDelegate.supplier(time, config, logContext, client, metadata, backgroundEventHandler, true, asyncConsumerMetrics);
 
         GroupRebalanceConfig groupRebalanceConfig = new GroupRebalanceConfig(
                 config,
@@ -583,7 +583,7 @@ public class ShareConsumerImpl<K, V> implements ShareConsumerDelegate<K, V> {
 
             do {
                 // Make sure the network thread can tell the application is actively polling
-                applicationEventHandler.add(new PollEvent(timer.currentTimeMs()));
+                applicationEventHandler.add(new SharePollEvent(timer.currentTimeMs()));
 
                 processBackgroundEvents();
 

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/AbstractTopicMetadataEvent.java

@@ -21,14 +21,14 @@ import org.apache.kafka.common.PartitionInfo;
 import java.util.List;
 import java.util.Map;
 
-public abstract class AbstractTopicMetadataEvent extends CompletableApplicationEvent<Map<String, List<PartitionInfo>>> {
+public abstract class AbstractTopicMetadataEvent extends CompletableApplicationEvent<Map<String, List<PartitionInfo>>> implements MetadataErrorNotifiableEvent {
 
     protected AbstractTopicMetadataEvent(final Type type, final long deadlineMs) {
         super(type, deadlineMs);
     }
 
     @Override
-    public boolean requireSubscriptionMetadata() {
-        return true;
+    public void onMetadataError(Exception metadataError) {
+        future().completeExceptionally(metadataError);
     }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/ApplicationEvent.java

@@ -28,14 +28,14 @@ import java.util.Objects;
 public abstract class ApplicationEvent {
 
     public enum Type {
-        COMMIT_ASYNC, COMMIT_SYNC, POLL, FETCH_COMMITTED_OFFSETS, NEW_TOPICS_METADATA_UPDATE, ASSIGNMENT_CHANGE,
+        COMMIT_ASYNC, COMMIT_SYNC, ASYNC_POLL, FETCH_COMMITTED_OFFSETS, NEW_TOPICS_METADATA_UPDATE, ASSIGNMENT_CHANGE,
         LIST_OFFSETS, CHECK_AND_UPDATE_POSITIONS, RESET_OFFSET, TOPIC_METADATA, ALL_TOPICS_METADATA,
         TOPIC_SUBSCRIPTION_CHANGE, TOPIC_PATTERN_SUBSCRIPTION_CHANGE, TOPIC_RE2J_PATTERN_SUBSCRIPTION_CHANGE,
         UPDATE_SUBSCRIPTION_METADATA, UNSUBSCRIBE,
         CONSUMER_REBALANCE_LISTENER_CALLBACK_COMPLETED,
         COMMIT_ON_CLOSE, CREATE_FETCH_REQUESTS, LEAVE_GROUP_ON_CLOSE, STOP_FIND_COORDINATOR_ON_CLOSE,
         PAUSE_PARTITIONS, RESUME_PARTITIONS, CURRENT_LAG,
-        SHARE_FETCH, SHARE_ACKNOWLEDGE_ASYNC, SHARE_ACKNOWLEDGE_SYNC,
+        SHARE_POLL, SHARE_FETCH, SHARE_ACKNOWLEDGE_ASYNC, SHARE_ACKNOWLEDGE_SYNC,
         SHARE_SUBSCRIPTION_CHANGE, SHARE_UNSUBSCRIBE,
         SHARE_ACKNOWLEDGE_ON_CLOSE,
         SHARE_ACKNOWLEDGEMENT_COMMIT_CALLBACK_REGISTRATION,

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/ApplicationEventProcessor.java

@@ -20,11 +20,15 @@ import org.apache.kafka.clients.consumer.OffsetAndMetadata;
 import org.apache.kafka.clients.consumer.internals.Acknowledgements;
 import org.apache.kafka.clients.consumer.internals.CachedSupplier;
 import org.apache.kafka.clients.consumer.internals.CommitRequestManager;
+import org.apache.kafka.clients.consumer.internals.ConsumerMembershipManager;
 import org.apache.kafka.clients.consumer.internals.ConsumerMetadata;
 import org.apache.kafka.clients.consumer.internals.ConsumerNetworkThread;
+import org.apache.kafka.clients.consumer.internals.ConsumerUtils;
 import org.apache.kafka.clients.consumer.internals.OffsetAndTimestampInternal;
 import org.apache.kafka.clients.consumer.internals.RequestManagers;
 import org.apache.kafka.clients.consumer.internals.ShareConsumeRequestManager;
+import org.apache.kafka.clients.consumer.internals.ShareMembershipManager;
+import org.apache.kafka.clients.consumer.internals.StreamsMembershipManager;
 import org.apache.kafka.clients.consumer.internals.SubscriptionState;
 import org.apache.kafka.common.Cluster;
 import org.apache.kafka.common.IsolationLevel;
@@ -45,6 +49,7 @@ import java.util.Map;
 import java.util.OptionalLong;
 import java.util.Set;
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionException;
 import java.util.function.BiConsumer;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -53,6 +58,7 @@ import java.util.stream.Collectors;
  * An {@link EventProcessor} that is created and executes in the {@link ConsumerNetworkThread network thread}
  * which processes {@link ApplicationEvent application events} generated by the application thread.
  */
+@SuppressWarnings({"ClassFanOutComplexity"})
 public class ApplicationEventProcessor implements EventProcessor<ApplicationEvent> {
 
     private final Logger log;
@@ -76,6 +82,14 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
     @Override
     public void process(ApplicationEvent event) {
         switch (event.type()) {
+            case ASYNC_POLL:
+                process((AsyncPollEvent) event);
+                return;
+
+            case SHARE_POLL:
+                process((SharePollEvent) event);
+                return;
+
             case COMMIT_ASYNC:
                 process((AsyncCommitEvent) event);
                 return;
@@ -84,10 +98,6 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
                 process((SyncCommitEvent) event);
                 return;
 
-            case POLL:
-                process((PollEvent) event);
-                return;
-
             case FETCH_COMMITTED_OFFSETS:
                 process((FetchCommittedOffsetsEvent) event);
                 return;
@@ -217,35 +227,15 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
         }
     }
 
-    private void process(final PollEvent event) {
-        // Trigger a reconciliation that can safely commit offsets if needed to rebalance,
-        // as we're processing before any new fetching starts in the app thread
+    private void process(final SharePollEvent event) {
         requestManagers.consumerMembershipManager.ifPresent(consumerMembershipManager ->
             consumerMembershipManager.maybeReconcile(true));
-        if (requestManagers.commitRequestManager.isPresent()) {
-            CommitRequestManager commitRequestManager = requestManagers.commitRequestManager.get();
-            commitRequestManager.updateTimerAndMaybeCommit(event.pollTimeMs());
-            // all commit request generation points have been passed,
-            // so it's safe to notify the app thread could proceed and start fetching
-            event.markReconcileAndAutoCommitComplete();
-            requestManagers.consumerHeartbeatRequestManager.ifPresent(hrm -> {
-                hrm.membershipManager().onConsumerPoll();
-                hrm.resetPollTimer(event.pollTimeMs());
-            });
-            requestManagers.streamsGroupHeartbeatRequestManager.ifPresent(hrm -> {
-                hrm.membershipManager().onConsumerPoll();
-                hrm.resetPollTimer(event.pollTimeMs());
-            });
-        } else {
-            // safe to unblock - no auto-commit risk here:
-            // 1. commitRequestManager is not present
-            // 2. shareConsumer has no auto-commit mechanism
-            event.markReconcileAndAutoCommitComplete();
-            requestManagers.shareHeartbeatRequestManager.ifPresent(hrm -> {
-                hrm.membershipManager().onConsumerPoll();
-                hrm.resetPollTimer(event.pollTimeMs());
-            });
-        }
+        requestManagers.shareHeartbeatRequestManager.ifPresent(hrm -> {
+            ShareMembershipManager membershipManager = hrm.membershipManager();
+            maybeUpdatePatternSubscription(membershipManager::onSubscriptionUpdated);
+            membershipManager.onConsumerPoll();
+            hrm.resetPollTimer(event.pollTimeMs());
+        });
     }
 
     private void process(final CreateFetchRequestsEvent event) {
@@ -352,7 +342,7 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
                 if (subscriptions.subscribe(event.topics(), event.listener())) {
                     this.metadataVersionSnapshot = metadata.requestUpdateForNewTopics();
                 }
-                requestManagers.streamsMembershipManager.get().onSubscriptionUpdated();
+                requestManagers.streamsGroupHeartbeatRequestManager.get().membershipManager().onSubscriptionUpdated();
                 event.future().complete(null);
             } catch (Exception e) {
                 event.future().completeExceptionally(e);
@@ -375,7 +365,10 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
         try {
             subscriptions.subscribe(event.pattern(), event.listener());
             metadata.requestUpdateForNewTopics();
-            updatePatternSubscription(metadata.fetch());
+            requestManagers.consumerHeartbeatRequestManager.ifPresent(hrm -> {
+                ConsumerMembershipManager membershipManager = hrm.membershipManager();
+                updatePatternSubscription(membershipManager::onSubscriptionUpdated, metadata.fetch());
+            });
             event.future().complete(null);
         } catch (Exception e) {
             event.future().completeExceptionally(e);
@@ -409,13 +402,7 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
      * This will make the consumer send the updated subscription on the next poll.
      */
     private void process(final UpdatePatternSubscriptionEvent event) {
-        if (!subscriptions.hasPatternSubscription()) {
-            return;
-        }
-        if (this.metadataVersionSnapshot < metadata.updateVersion()) {
-            this.metadataVersionSnapshot = metadata.updateVersion();
-            updatePatternSubscription(metadata.fetch());
-        }
+        requestManagers.consumerMembershipManager.ifPresent(mm -> maybeUpdatePatternSubscription(mm::onSubscriptionUpdated));
         event.future().complete(null);
     }
 
@@ -726,6 +713,75 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
         requestManagers.streamsMembershipManager.get().onAllTasksLostCallbackCompleted(event);
     }
 
+    private void process(final AsyncPollEvent event) {
+        log.trace("Processing poll logic for {}", event);
+
+        // Trigger a reconciliation that can safely commit offsets if needed to rebalance,
+        // as we're processing before any new fetching starts
+        requestManagers.consumerMembershipManager.ifPresent(consumerMembershipManager ->
+            consumerMembershipManager.maybeReconcile(true));
+
+        if (requestManagers.commitRequestManager.isPresent()) {
+            CommitRequestManager commitRequestManager = requestManagers.commitRequestManager.get();
+            commitRequestManager.updateTimerAndMaybeCommit(event.pollTimeMs());
+
+            requestManagers.consumerHeartbeatRequestManager.ifPresent(hrm -> {
+                ConsumerMembershipManager membershipManager = hrm.membershipManager();
+                maybeUpdatePatternSubscription(membershipManager::onSubscriptionUpdated);
+                membershipManager.onConsumerPoll();
+                hrm.resetPollTimer(event.pollTimeMs());
+            });
+            requestManagers.streamsGroupHeartbeatRequestManager.ifPresent(hrm -> {
+                StreamsMembershipManager membershipManager = hrm.membershipManager();
+                maybeUpdatePatternSubscription(membershipManager::onSubscriptionUpdated);
+                membershipManager.onConsumerPoll();
+                hrm.resetPollTimer(event.pollTimeMs());
+            });
+        }
+
+        log.trace("Processing check and update positions logic for {}", event);
+        CompletableFuture<Boolean> updatePositionsFuture = requestManagers.offsetsRequestManager.updateFetchPositions(event.deadlineMs());
+
+        updatePositionsFuture.whenComplete((__, updatePositionsError) -> {
+            if (maybeCompleteAsyncPollEventExceptionally(event, updatePositionsError))
+                return;
+
+            log.trace("Processing create fetch requests logic for {}", event);
+
+            // Create a fetch request if there's no data in the FetchBuffer.
+            requestManagers.fetchRequestManager.createFetchRequests().whenComplete((___, fetchError) -> {
+                if (maybeCompleteAsyncPollEventExceptionally(event, fetchError))
+                    return;
+
+                event.completeSuccessfully();
+                log.trace("Completed event processing for {}", event);
+            });
+        });
+    }
+
+    /**
+     * If there's an error to report to the user, the current event will be completed and this method will
+     * return {@code true}. Otherwise, it will return {@code false}.
+     */
+    private boolean maybeCompleteAsyncPollEventExceptionally(AsyncPollEvent event, Throwable t) {
+        if (t == null)
+            return false;
+
+        if (t instanceof org.apache.kafka.common.errors.TimeoutException || t instanceof java.util.concurrent.TimeoutException) {
+            log.trace("Ignoring timeout for {}: {}", event, t.getMessage());
+            return false;
+        }
+
+        if (t instanceof CompletionException) {
+            t = t.getCause();
+        }
+
+        KafkaException e = ConsumerUtils.maybeWrapAsKafkaException(t);
+        event.completeExceptionally(e);
+        log.trace("Failing event processing for {}", event, e);
+        return true;
+    }
+
     private <T> BiConsumer<? super T, ? super Throwable> complete(final CompletableFuture<T> b) {
         return (value, exception) -> {
             if (exception != null)
@@ -757,6 +813,16 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
         };
     }
 
+    private void maybeUpdatePatternSubscription(OnSubscriptionUpdatedCallback callback) {
+        if (!subscriptions.hasPatternSubscription()) {
+            return;
+        }
+        if (this.metadataVersionSnapshot < metadata.updateVersion()) {
+            this.metadataVersionSnapshot = metadata.updateVersion();
+            updatePatternSubscription(callback, metadata.fetch());
+        }
+    }
+
     /**
      * This function evaluates the regex that the consumer subscribed to
      * against the list of topic names from metadata, and updates
@@ -764,26 +830,26 @@ public class ApplicationEventProcessor implements EventProcessor<ApplicationEven
      *
      * @param cluster Cluster from which we get the topics
      */
-    private void updatePatternSubscription(Cluster cluster) {
-        if (requestManagers.consumerHeartbeatRequestManager.isEmpty()) {
-            log.warn("Group membership manager not present when processing a subscribe event");
-            return;
-        }
+    private void updatePatternSubscription(OnSubscriptionUpdatedCallback callback, Cluster cluster) {
         final Set<String> topicsToSubscribe = cluster.topics().stream()
             .filter(subscriptions::matchesSubscribedPattern)
             .collect(Collectors.toSet());
         if (subscriptions.subscribeFromPattern(topicsToSubscribe)) {
             this.metadataVersionSnapshot = metadata.requestUpdateForNewTopics();
-
         }
         // Join the group if not already part of it, or just send the updated subscription
         // to the broker on the next poll. Note that this is done even if no topics matched
         // the regex, to ensure the member joins the group if needed (with empty subscription).
-        requestManagers.consumerHeartbeatRequestManager.get().membershipManager().onSubscriptionUpdated();
+        callback.onSubscriptionUpdated();
     }
 
     // Visible for testing
     int metadataVersionSnapshot() {
         return metadataVersionSnapshot;
     }
+
+    private interface OnSubscriptionUpdatedCallback {
+
+        void onSubscriptionUpdated();
+    }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/AsyncPollEvent.java

@@ -0,0 +1,100 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.clients.consumer.internals.events;
+
+import org.apache.kafka.clients.consumer.Consumer;
+import org.apache.kafka.clients.consumer.internals.AsyncKafkaConsumer;
+import org.apache.kafka.clients.consumer.internals.ClassicKafkaConsumer;
+import org.apache.kafka.clients.consumer.internals.ConsumerUtils;
+import org.apache.kafka.common.KafkaException;
+
+import java.time.Duration;
+import java.util.Optional;
+
+/**
+ * This class represents the non-blocking event that executes logic functionally equivalent to the following:
+ *
+ * <ul>
+ *     <li>Polling</li>
+ *     <li>{@link CheckAndUpdatePositionsEvent}</li>
+ *     <li>{@link CreateFetchRequestsEvent}</li>
+ * </ul>
+ *
+ * {@link AsyncKafkaConsumer#poll(Duration)} is implemented using a non-blocking design to ensure performance is
+ * at the same level as {@link ClassicKafkaConsumer#poll(Duration)}. The event is submitted in {@code poll()}, but
+ * there are no blocking waits for the "result" of the event. Checks are made for the result at certain points, but
+ * they do not block. The logic for the previously-mentioned events is executed sequentially on the background thread.
+ */
+public class AsyncPollEvent extends ApplicationEvent implements MetadataErrorNotifiableEvent {
+
+    private final long deadlineMs;
+    private final long pollTimeMs;
+    private volatile KafkaException error;
+    private volatile boolean isComplete;
+
+    /**
+     * Creates a new event to signify a multi-stage processing of {@link Consumer#poll(Duration)} logic.
+     *
+     * @param deadlineMs        Time, in milliseconds, at which point the event must be completed; based on the
+     *                          {@link Duration} passed to {@link Consumer#poll(Duration)}
+     * @param pollTimeMs        Time, in milliseconds, at which point the event was created
+     */
+    public AsyncPollEvent(long deadlineMs, long pollTimeMs) {
+        super(Type.ASYNC_POLL);
+        this.deadlineMs = deadlineMs;
+        this.pollTimeMs = pollTimeMs;
+    }
+
+    public long deadlineMs() {
+        return deadlineMs;
+    }
+
+    public long pollTimeMs() {
+        return pollTimeMs;
+    }
+
+    public Optional<KafkaException> error() {
+        return Optional.ofNullable(error);
+    }
+
+    public boolean isComplete() {
+        return isComplete;
+    }
+
+    public void completeSuccessfully() {
+        isComplete = true;
+    }
+
+    public void completeExceptionally(KafkaException e) {
+        isComplete = true;
+        this.error = e;
+    }
+
+    @Override
+    public void onMetadataError(Exception metadataError) {
+        completeExceptionally(ConsumerUtils.maybeWrapAsKafkaException(metadataError));
+    }
+
+    @Override
+    protected String toStringBase() {
+        return super.toStringBase() +
+            ", deadlineMs=" + deadlineMs +
+            ", pollTimeMs=" + pollTimeMs +
+            ", error=" + error +
+            ", isComplete=" + isComplete;
+    }
+}

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/BackgroundEventHandler.java

@@ -45,6 +45,16 @@ public class BackgroundEventHandler {
         this.asyncConsumerMetrics = asyncConsumerMetrics;
     }
 
+    /**
+     * Returns the current size of the queue. Used by the background thread to determine if it needs to <i>pause</i>
+     * itself to return to the application thread for processing.
+     *
+     * @return Current size of queue
+     */
+    public int size() {
+        return backgroundEventQueue.size();
+    }
+
     /**
      * Add a {@link BackgroundEvent} to the handler.
      *

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/CheckAndUpdatePositionsEvent.java

@@ -17,6 +17,7 @@
 
 package org.apache.kafka.clients.consumer.internals.events;
 
+import org.apache.kafka.clients.consumer.Consumer;
 import org.apache.kafka.clients.consumer.internals.SubscriptionState;
 import org.apache.kafka.common.TopicPartition;
 
@@ -30,7 +31,7 @@ import java.time.Duration;
  * The event completes with a boolean indicating if all assigned partitions have valid fetch positions
  * (based on {@link SubscriptionState#hasAllFetchPositions()}).
  */
-public class CheckAndUpdatePositionsEvent extends CompletableApplicationEvent<Boolean> {
+public class CheckAndUpdatePositionsEvent extends CompletableApplicationEvent<Boolean> implements MetadataErrorNotifiableEvent {
 
     public CheckAndUpdatePositionsEvent(long deadlineMs) {
         super(Type.CHECK_AND_UPDATE_POSITIONS, deadlineMs);
@@ -39,11 +40,11 @@ public class CheckAndUpdatePositionsEvent extends CompletableApplicationEvent<Bo
     /**
      * Indicates that this event requires subscription metadata to be present
      * for its execution. This is used to ensure that metadata errors are
-     * handled correctly during the {@link org.apache.kafka.clients.consumer.internals.AsyncKafkaConsumer#poll(Duration) poll} 
-     * or {@link org.apache.kafka.clients.consumer.internals.AsyncKafkaConsumer#position(TopicPartition) position} process.
+     * handled correctly during the {@link Consumer#poll(Duration) poll}
+     * or {@link Consumer#position(TopicPartition) position} process.
      */
     @Override
-    public boolean requireSubscriptionMetadata() {
-        return true;
+    public void onMetadataError(Exception metadataError) {
+        future().completeExceptionally(metadataError);
     }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/CompletableApplicationEvent.java

@@ -52,8 +52,4 @@ public abstract class CompletableApplicationEvent<T> extends ApplicationEvent im
     protected String toStringBase() {
         return super.toStringBase() + ", future=" + future + ", deadlineMs=" + deadlineMs;
     }
-    
-    public boolean requireSubscriptionMetadata() {
-        return false;
-    }
 }

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/ListOffsetsEvent.java

@@ -32,7 +32,7 @@ import java.util.Map;
  * {@link OffsetAndTimestamp} found (offset of the first message whose timestamp is greater than
  * or equals to the target timestamp)
  */
-public class ListOffsetsEvent extends CompletableApplicationEvent<Map<TopicPartition, OffsetAndTimestampInternal>> {
+public class ListOffsetsEvent extends CompletableApplicationEvent<Map<TopicPartition, OffsetAndTimestampInternal>> implements MetadataErrorNotifiableEvent {
     private final Map<TopicPartition, Long> timestampsToSearch;
     private final boolean requireTimestamps;
 
@@ -65,8 +65,8 @@ public class ListOffsetsEvent extends CompletableApplicationEvent<Map<TopicParti
     }
 
     @Override
-    public boolean requireSubscriptionMetadata() {
-        return true;
+    public void onMetadataError(Exception metadataError) {
+        future().completeExceptionally(metadataError);
     }
 
     @Override

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/MetadataErrorNotifiableEvent.java

@@ -0,0 +1,56 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.clients.consumer.internals.events;
+
+import org.apache.kafka.clients.Metadata;
+import org.apache.kafka.clients.consumer.internals.ConsumerNetworkThread;
+import org.apache.kafka.clients.consumer.internals.NetworkClientDelegate;
+
+/**
+ * This interface is used for events that need to be notified when the
+ * {@link NetworkClientDelegate#getAndClearMetadataError()} has an error.
+ */
+public interface MetadataErrorNotifiableEvent {
+
+    /**
+     * The background thread detects metadata errors on every call to {@link NetworkClientDelegate#poll(long, long)}.
+     * {@link NetworkClientDelegate} calls {@link Metadata#maybeThrowAnyException()} and stores the result.
+     * The presence of a metadata error is checked in the {@link ConsumerNetworkThread}'s loop by calling
+     * {@link NetworkClientDelegate#getAndClearMetadataError()}. There are two places in the loop in which the
+     * metadata error is checked:
+     *
+     * <ul>
+     *     <li>
+     *         At the very top of the {@link ConsumerNetworkThread}'s loop, the {@link ApplicationEventHandler}'s
+     *         queue is drained. Before processing each event via
+     *         {@link ApplicationEventProcessor#process(ApplicationEvent)}, if a metadata error occurred, this method
+     *         will be invoked on the event if it implements this interface.
+     *         <p/>
+     *         <em>Note</em>: for an event on which this method is invoked, it will <em>not</em> be passed to the
+     *         {@link ApplicationEventProcessor#process(ApplicationEvent)} method.
+     *     </li>
+     *     <li>
+     *         At the very bottom of the {@link ConsumerNetworkThread}'s loop, the {@link CompletableEventReaper}
+     *         is executed and any outstanding event is returned. If a metadata error occurred, this method
+     *         will be invoked on all unexpired events if it implements this interface.
+     *     </li>
+     * </ul>
+     *
+     * @param metadataError Error that originally came from {@link Metadata#maybeThrowAnyException()}
+     */
+    void onMetadataError(Exception metadataError);
+}

clients/src/main/java/org/apache/kafka/clients/consumer/internals/events/SharePollEvent.java

@@ -16,28 +16,12 @@
  */
 package org.apache.kafka.clients.consumer.internals.events;
 
-import java.util.concurrent.CompletableFuture;
-
-public class PollEvent extends ApplicationEvent {
+public class SharePollEvent extends ApplicationEvent {
 
     private final long pollTimeMs;
 
-    /**
-     * A future that represents the completion of reconciliation and auto-commit
-     * processing.
-     * This future is completed when all commit request generation points have
-     * been passed, including:
-     * <ul>
-     *   <li>auto-commit on rebalance</li>
-     *   <li>auto-commit on the interval</li>
-     * </ul>
-     * Once completed, it signals that it's safe for the consumer to proceed with
-     * fetching new records.
-     */
-    private final CompletableFuture<Void> reconcileAndAutoCommit = new CompletableFuture<>();
-
-    public PollEvent(final long pollTimeMs) {
-        super(Type.POLL);
+    public SharePollEvent(final long pollTimeMs) {
+        super(Type.SHARE_POLL);
         this.pollTimeMs = pollTimeMs;
     }
 
@@ -45,14 +29,6 @@ public class PollEvent extends ApplicationEvent {
         return pollTimeMs;
     }
 
-    public CompletableFuture<Void> reconcileAndAutoCommit() {
-        return reconcileAndAutoCommit;
-    }
-
-    public void markReconcileAndAutoCommitComplete() {
-        reconcileAndAutoCommit.complete(null);
-    }
-
     @Override
     public String toStringBase() {
         return super.toStringBase() + ", pollTimeMs=" + pollTimeMs;

clients/src/test/java/org/apache/kafka/clients/consumer/ConsumerPollTestUtils.java

@@ -0,0 +1,103 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.kafka.clients.consumer;
+
+import org.apache.kafka.clients.consumer.internals.AsyncKafkaConsumer;
+import org.apache.kafka.common.errors.InterruptException;
+import org.apache.kafka.common.errors.TimeoutException;
+import org.apache.kafka.common.utils.Time;
+import org.apache.kafka.common.utils.Timer;
+import org.apache.kafka.test.TestUtils;
+
+import java.time.Duration;
+import java.util.function.Function;
+import java.util.function.Supplier;
+
+import static org.apache.kafka.test.TestUtils.DEFAULT_MAX_WAIT_MS;
+
+/**
+ * This class provides utilities for tests to wait for a call to {@link Consumer#poll(Duration)} to produce a
+ * result (error, records, specific condition, etc.). This is mostly due to the subtle difference in behavior
+ * of the non-blocking {@link AsyncKafkaConsumer}. A single pass of {@link AsyncKafkaConsumer#poll(Duration)}
+ * may not be sufficient to provide an immediate result.
+ */
+public class ConsumerPollTestUtils {
+
+    /**
+     * Wait up to {@link TestUtils#DEFAULT_MAX_WAIT_MS} to return records from the given {@link Consumer}.
+     */
+    public static <T> ConsumerRecords<T, T> waitForRecords(Consumer<?, ?> consumer) {
+        Timer timer = Time.SYSTEM.timer(DEFAULT_MAX_WAIT_MS);
+
+        while (timer.notExpired()) {
+            @SuppressWarnings("unchecked")
+            ConsumerRecords<T, T> records = (ConsumerRecords<T, T>) consumer.poll(Duration.ofMillis(1000));
+
+            if (!records.isEmpty())
+                return records;
+
+            timer.update();
+        }
+
+        throw new TimeoutException("no records to return");
+    }
+
+    /**
+     * Wait up to {@link TestUtils#DEFAULT_MAX_WAIT_MS} for the {@link Consumer} to produce the side effect
+     * that causes {@link Supplier condition} to evaluate to {@code true}.
+     */
+    public static void waitForCondition(Consumer<?, ?> consumer,
+                                        Supplier<Boolean> testCondition,
+                                        String conditionDetails) {
+        try {
+            TestUtils.waitForCondition(
+                () -> {
+                    consumer.poll(Duration.ZERO);
+                    return testCondition.get();
+                },
+                conditionDetails
+            );
+        } catch (InterruptedException e) {
+            throw new InterruptException(e);
+        }
+    }
+
+    /**
+     * Wait up to {@link TestUtils#DEFAULT_MAX_WAIT_MS} for the {@link Consumer} to throw an exception that,
+     * when tested against the {@link Function condition}, will evaluate to {@code true}.
+     */
+    public static void waitForException(Consumer<?, ?> consumer,
+                                        Function<Throwable, Boolean> testCondition,
+                                        String conditionDetails) {
+        try {
+            TestUtils.waitForCondition(
+                () -> {
+                    try {
+                        consumer.poll(Duration.ZERO);
+                        return false;
+                    } catch (Throwable t) {
+                        return testCondition.apply(t);
+                    }
+                },
+                conditionDetails
+            );
+        } catch (InterruptedException e) {
+            throw new InterruptException(e);
+        }
+    }
+
+}

clients/src/test/java/org/apache/kafka/clients/consumer/KafkaConsumerTest.java

@@ -935,7 +935,6 @@ public class KafkaConsumerTest {
 
     @ParameterizedTest
     @EnumSource(GroupProtocol.class)
-    @SuppressWarnings("unchecked")
     public void verifyNoCoordinatorLookupForManualAssignmentWithSeek(GroupProtocol groupProtocol) {
         ConsumerMetadata metadata = createMetadata(subscription);
         MockClient client = new MockClient(time, metadata);
@@ -951,7 +950,7 @@ public class KafkaConsumerTest {
         client.prepareResponse(listOffsetsResponse(Map.of(tp0, 50L)));
         client.prepareResponse(fetchResponse(tp0, 50L, 5));
 
-        ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ofMillis(1));
+        ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
         assertEquals(5, records.count());
         assertEquals(55L, consumer.position(tp0));
         assertEquals(1, records.nextOffsets().size());
@@ -1045,8 +1044,7 @@ public class KafkaConsumerTest {
 
             }, fetchResponse(tp0, 50L, 5));
 
-        @SuppressWarnings("unchecked")
-        ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ofMillis(1));
+        ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
         assertEquals(5, records.count());
         assertEquals(Set.of(tp0), records.partitions());
         assertEquals(1, records.nextOffsets().size());
@@ -1065,7 +1063,7 @@ public class KafkaConsumerTest {
 
     @ParameterizedTest
     @EnumSource(value = GroupProtocol.class)
-    public void testMissingOffsetNoResetPolicy(GroupProtocol groupProtocol) throws InterruptedException {
+    public void testMissingOffsetNoResetPolicy(GroupProtocol groupProtocol) {
         SubscriptionState subscription = new SubscriptionState(new LogContext(), AutoOffsetResetStrategy.NONE);
         ConsumerMetadata metadata = createMetadata(subscription);
         MockClient client = new MockClient(time, metadata);
@@ -1081,15 +1079,14 @@ public class KafkaConsumerTest {
                 true, groupId, groupInstanceId, false);
         consumer.assign(List.of(tp0));
 
-        if (groupProtocol == GroupProtocol.CONSUMER) {
-            // New consumer poll(ZERO) needs to wait for the offset fetch event added by a call to poll, to be processed
-            // by the background thread, so it can realize there are no committed offsets and then
-            // throw the NoOffsetForPartitionException
-            assertPollEventuallyThrows(consumer, NoOffsetForPartitionException.class,
-                    "Consumer was not able to update fetch positions on continuous calls with 0 timeout");
-        } else {
-            assertThrows(NoOffsetForPartitionException.class, () -> consumer.poll(Duration.ZERO));
-        }
+        // Consumer.poll(0) needs to wait for the offset fetch event added by a call to poll, to be processed
+        // by the background thread, so it can realize there are no committed offsets and then
+        // throw the NoOffsetForPartitionException.
+        ConsumerPollTestUtils.waitForException(
+            consumer,
+            NoOffsetForPartitionException.class::isInstance,
+            "Consumer was not able to update fetch positions on continuous calls with 0 timeout"
+        );
     }
 
     @ParameterizedTest
@@ -1731,7 +1728,6 @@ public class KafkaConsumerTest {
 
     @ParameterizedTest
     @EnumSource(GroupProtocol.class)
-    @SuppressWarnings("unchecked")
     public void testManualAssignmentChangeWithAutoCommitEnabled(GroupProtocol groupProtocol) {
         ConsumerMetadata metadata = createMetadata(subscription);
         MockClient client = new MockClient(time, metadata);
@@ -1766,7 +1762,7 @@ public class KafkaConsumerTest {
         client.prepareResponse(listOffsetsResponse(Map.of(tp0, 10L)));
         client.prepareResponse(fetchResponse(tp0, 10L, 1));
 
-        ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ofMillis(100));
+        ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
 
         assertEquals(1, records.count());
         assertEquals(11L, consumer.position(tp0));
@@ -1825,8 +1821,7 @@ public class KafkaConsumerTest {
         client.prepareResponse(listOffsetsResponse(Map.of(tp0, 10L)));
         client.prepareResponse(fetchResponse(tp0, 10L, 1));
 
-        @SuppressWarnings("unchecked")
-        ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ofMillis(1));
+        ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
         assertEquals(1, records.count());
         assertEquals(11L, consumer.position(tp0));
         assertEquals(1, records.nextOffsets().size());
@@ -2121,7 +2116,7 @@ public class KafkaConsumerTest {
         time.sleep(heartbeatIntervalMs);
         Thread.sleep(heartbeatIntervalMs);
         consumer.updateAssignmentMetadataIfNeeded(time.timer(Long.MAX_VALUE));
-        final ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ZERO);
+        final ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
         assertFalse(records.isEmpty());
         assertFalse(records.nextOffsets().isEmpty());
     }
@@ -2271,19 +2266,18 @@ public class KafkaConsumerTest {
 
     @ParameterizedTest
     @EnumSource(GroupProtocol.class)
-    public void testPollAuthenticationFailure(GroupProtocol groupProtocol) throws InterruptedException {
+    public void testPollAuthenticationFailure(GroupProtocol groupProtocol) {
         final KafkaConsumer<String, String> consumer = consumerWithPendingAuthenticationError(groupProtocol);
         consumer.subscribe(Set.of(topic));
 
-        if (groupProtocol == GroupProtocol.CONSUMER) {
-            // New consumer poll(ZERO) needs to wait for the event added by a call to poll, to be processed
-            // by the background thread, so it can realize there is authentication fail  and then
-            // throw the AuthenticationException
-            assertPollEventuallyThrows(consumer, AuthenticationException.class,
-                    "this consumer was not able to discover metadata errors during continuous polling.");
-        } else {
-            assertThrows(AuthenticationException.class, () -> consumer.poll(Duration.ZERO));
-        }
+        // Consumer.poll(0) needs to wait for the event added by a call to poll, to be processed
+        // by the background thread, so it can realize there is authentication fail and then
+        // throw the AuthenticationException.
+        ConsumerPollTestUtils.waitForException(
+            consumer,
+            AuthenticationException.class::isInstance,
+            "this consumer was not able to discover metadata errors during continuous polling."
+        );
     }
 
     // TODO: this test triggers a bug with the CONSUMER group protocol implementation.
@@ -2655,7 +2649,6 @@ public class KafkaConsumerTest {
 
     @ParameterizedTest
     @EnumSource(GroupProtocol.class)
-    @SuppressWarnings("unchecked")
     public void testCurrentLag(GroupProtocol groupProtocol) throws InterruptedException {
         final ConsumerMetadata metadata = createMetadata(subscription);
         final MockClient client = new MockClient(time, metadata);
@@ -2670,9 +2663,11 @@ public class KafkaConsumerTest {
         consumer.assign(Set.of(tp0));
 
         // poll once to update with the current metadata
-        consumer.poll(Duration.ofMillis(0));
-        TestUtils.waitForCondition(() -> requestGenerated(client, ApiKeys.FIND_COORDINATOR),
-                "No metadata requests sent");
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            () -> requestGenerated(client, ApiKeys.FIND_COORDINATOR),
+            "No metadata requests sent"
+        );
         client.respond(FindCoordinatorResponse.prepareResponse(Errors.NONE, groupId, metadata.fetch().nodes().get(0)));
 
         // no error for no current position
@@ -2685,13 +2680,12 @@ public class KafkaConsumerTest {
         }
         // poll once again, which should send the list-offset request
         consumer.seek(tp0, 50L);
-        consumer.poll(Duration.ofMillis(0));
-        // requests: list-offset, fetch
-        TestUtils.waitForCondition(() -> {
-            boolean hasListOffsetRequest = requestGenerated(client, ApiKeys.LIST_OFFSETS);
-            boolean hasFetchRequest = requestGenerated(client, ApiKeys.FETCH);
-            return hasListOffsetRequest && hasFetchRequest;
-        }, "No list-offset & fetch request sent");
+        // requests: list-offset
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            () -> requestGenerated(client, ApiKeys.LIST_OFFSETS),
+            "No list-offset sent"
+        );
 
         // no error for no end offset (so unknown lag)
         assertEquals(OptionalLong.empty(), consumer.currentLag(tp0));
@@ -2700,7 +2694,12 @@ public class KafkaConsumerTest {
         // and hence next call would return correct lag result
         ClientRequest listOffsetRequest = findRequest(client, ApiKeys.LIST_OFFSETS);
         client.respondToRequest(listOffsetRequest, listOffsetsResponse(Map.of(tp0, 90L)));
-        consumer.poll(Duration.ofMillis(0));
+        // requests: fetch
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            () -> requestGenerated(client, ApiKeys.FETCH),
+            "No fetch sent"
+        );
 
         // For AsyncKafkaConsumer, subscription state is updated in background, so the result will eventually be updated.
         TestUtils.waitForCondition(() -> {
@@ -2715,7 +2714,7 @@ public class KafkaConsumerTest {
         final FetchInfo fetchInfo = new FetchInfo(1L, 99L, 50L, 5);
         client.respondToRequest(fetchRequest, fetchResponse(Map.of(tp0, fetchInfo)));
 
-        final ConsumerRecords<String, String> records = (ConsumerRecords<String, String>) consumer.poll(Duration.ofMillis(1));
+        final ConsumerRecords<String, String> records = ConsumerPollTestUtils.waitForRecords(consumer);
         assertEquals(5, records.count());
         assertEquals(55L, consumer.position(tp0));
         assertEquals(1, records.nextOffsets().size());
@@ -3194,27 +3193,14 @@ public class KafkaConsumerTest {
         KafkaConsumer<String, String> consumer = newConsumer(groupProtocol, time, client, subscription, metadata, assignor, true, groupInstanceId);
         consumer.subscribe(Set.of(invalidTopicName), getConsumerRebalanceListener(consumer));
 
-        if (groupProtocol == GroupProtocol.CONSUMER) {
-            // New consumer poll(ZERO) needs to wait for the event added by a call to poll, to be processed
-            // by the background thread, so it can realize there is invalid topics and then
-            // throw the InvalidTopicException
-            assertPollEventuallyThrows(consumer, InvalidTopicException.class,
-                    "Consumer was not able to update fetch positions on continuous calls with 0 timeout");
-        } else {
-            assertThrows(InvalidTopicException.class, () -> consumer.poll(Duration.ZERO));
-        }
-    }
-
-    private static <T extends Throwable> void assertPollEventuallyThrows(KafkaConsumer<?, ?> consumer,
-            Class<T> expectedException, String errMsg) throws InterruptedException {
-        TestUtils.waitForCondition(() -> {
-            try {
-                consumer.poll(Duration.ZERO);
-                return false;
-            } catch (Throwable exception) {
-                return expectedException.isInstance(exception);
-            }
-        }, errMsg);
+        // Consumer.poll(0) needs to wait for the event added by a call to poll, to be processed
+        // by the background thread, so it can realize there is invalid topics and then
+        // throw the InvalidTopicException.
+        ConsumerPollTestUtils.waitForException(
+            consumer,
+            InvalidTopicException.class::isInstance,
+            "Consumer was not able to update fetch positions on continuous calls with 0 timeout"
+        );
     }
 
     @ParameterizedTest
@@ -3654,7 +3640,11 @@ public void testPollIdleRatio(GroupProtocol groupProtocol) {
         service.execute(() -> consumer.poll(Duration.ofSeconds(5)));
         try {
             TimeUnit.SECONDS.sleep(1);
-            assertThrows(ConcurrentModificationException.class, () -> consumer.poll(Duration.ZERO));
+            ConsumerPollTestUtils.waitForException(
+                consumer,
+                t -> t instanceof ConcurrentModificationException,
+                "Consumer did not throw ConcurrentModificationException within timeout"
+            );
             client.wakeup();
             consumer.wakeup();
         } finally {

clients/src/test/java/org/apache/kafka/clients/consumer/internals/ApplicationEventHandlerTest.java

@@ -19,8 +19,8 @@ package org.apache.kafka.clients.consumer.internals;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventHandler;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventProcessor;
+import org.apache.kafka.clients.consumer.internals.events.AsyncPollEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.metrics.AsyncConsumerMetrics;
 import org.apache.kafka.common.metrics.Metrics;
 import org.apache.kafka.common.utils.LogContext;
@@ -61,7 +61,7 @@ public class ApplicationEventHandlerTest {
                      asyncConsumerMetrics
              )) {
             // add event
-            applicationEventHandler.add(new PollEvent(time.milliseconds()));
+            applicationEventHandler.add(new AsyncPollEvent(time.milliseconds() + 10, time.milliseconds()));
             verify(asyncConsumerMetrics).recordApplicationEventQueueSize(1);
         }
     }

clients/src/test/java/org/apache/kafka/clients/consumer/internals/AsyncKafkaConsumerTest.java

@@ -22,6 +22,7 @@ import org.apache.kafka.clients.NodeApiVersions;
 import org.apache.kafka.clients.consumer.CloseOptions;
 import org.apache.kafka.clients.consumer.ConsumerConfig;
 import org.apache.kafka.clients.consumer.ConsumerGroupMetadata;
+import org.apache.kafka.clients.consumer.ConsumerPollTestUtils;
 import org.apache.kafka.clients.consumer.ConsumerRebalanceListener;
 import org.apache.kafka.clients.consumer.ConsumerRecord;
 import org.apache.kafka.clients.consumer.ConsumerRecords;
@@ -35,6 +36,7 @@ import org.apache.kafka.clients.consumer.internals.events.ApplicationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventHandler;
 import org.apache.kafka.clients.consumer.internals.events.AssignmentChangeEvent;
 import org.apache.kafka.clients.consumer.internals.events.AsyncCommitEvent;
+import org.apache.kafka.clients.consumer.internals.events.AsyncPollEvent;
 import org.apache.kafka.clients.consumer.internals.events.BackgroundEvent;
 import org.apache.kafka.clients.consumer.internals.events.CheckAndUpdatePositionsEvent;
 import org.apache.kafka.clients.consumer.internals.events.CommitEvent;
@@ -43,13 +45,11 @@ import org.apache.kafka.clients.consumer.internals.events.CompletableApplication
 import org.apache.kafka.clients.consumer.internals.events.CompletableBackgroundEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
 import org.apache.kafka.clients.consumer.internals.events.ConsumerRebalanceListenerCallbackNeededEvent;
-import org.apache.kafka.clients.consumer.internals.events.CreateFetchRequestsEvent;
 import org.apache.kafka.clients.consumer.internals.events.ErrorEvent;
 import org.apache.kafka.clients.consumer.internals.events.EventProcessor;
 import org.apache.kafka.clients.consumer.internals.events.FetchCommittedOffsetsEvent;
 import org.apache.kafka.clients.consumer.internals.events.LeaveGroupOnCloseEvent;
 import org.apache.kafka.clients.consumer.internals.events.ListOffsetsEvent;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ResetOffsetEvent;
 import org.apache.kafka.clients.consumer.internals.events.SeekUnvalidatedEvent;
 import org.apache.kafka.clients.consumer.internals.events.SyncCommitEvent;
@@ -112,6 +112,7 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 import java.util.Properties;
 import java.util.Set;
@@ -154,6 +155,7 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.junit.jupiter.api.Assertions.fail;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.atLeast;
+import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.clearInvocations;
 import static org.mockito.Mockito.doAnswer;
 import static org.mockito.Mockito.doReturn;
@@ -424,7 +426,7 @@ public class AsyncKafkaConsumerTest {
 
         consumer.wakeup();
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         assertThrows(WakeupException.class, () -> consumer.poll(Duration.ZERO));
         assertDoesNotThrow(() -> consumer.poll(Duration.ZERO));
     }
@@ -444,7 +446,7 @@ public class AsyncKafkaConsumerTest {
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singleton(tp));
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         assertThrows(WakeupException.class, () -> consumer.poll(Duration.ofMinutes(1)));
         assertDoesNotThrow(() -> consumer.poll(Duration.ZERO));
     }
@@ -468,7 +470,7 @@ public class AsyncKafkaConsumerTest {
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singleton(tp));
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         // since wakeup() is called when the non-empty fetch is returned the wakeup should be ignored
         assertDoesNotThrow(() -> consumer.poll(Duration.ofMinutes(1)));
         // the previously ignored wake-up should not be ignored in the next call
@@ -505,9 +507,12 @@ public class AsyncKafkaConsumerTest {
 
         completeTopicSubscriptionChangeEventSuccessfully();
         consumer.subscribe(Collections.singletonList(topicName), listener);
-        markReconcileAndAutoCommitCompleteForPollEvent();
-        consumer.poll(Duration.ZERO);
-        assertTrue(callbackExecuted.get());
+        completeAsyncPollEventSuccessfully();
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            callbackExecuted::get,
+            "Consumer.poll() did not execute callback within timeout"
+        );
     }
 
     @Test
@@ -527,7 +532,7 @@ public class AsyncKafkaConsumerTest {
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singleton(tp));
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         consumer.poll(Duration.ZERO);
 
         assertDoesNotThrow(() -> consumer.poll(Duration.ZERO));
@@ -673,8 +678,12 @@ public class AsyncKafkaConsumerTest {
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(Collections.singleton(new TopicPartition("foo", 0)));
         assertDoesNotThrow(() -> consumer.commitAsync(new HashMap<>(), callback));
-        markReconcileAndAutoCommitCompleteForPollEvent();
-        assertMockCommitCallbackInvoked(() -> consumer.poll(Duration.ZERO), callback);
+        completeAsyncPollEventSuccessfully();
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            () -> callback.invoked == 1 && callback.exception == null,
+            "Consumer.poll() did not execute the callback once (without error) in allottec timeout"
+        );
     }
 
     @Test
@@ -1455,7 +1464,7 @@ public class AsyncKafkaConsumerTest {
                                             int expectedRevokedCount,
                                             int expectedAssignedCount,
                                             int expectedLostCount,
-                                            Optional<RuntimeException> expectedException
+                                            Optional<RuntimeException> expectedExceptionOpt
                                             ) {
         consumer = newConsumer();
         CounterConsumerRebalanceListener consumerRebalanceListener = new CounterConsumerRebalanceListener(
@@ -1473,13 +1482,18 @@ public class AsyncKafkaConsumerTest {
             backgroundEventQueue.add(e);
         }
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         // This will trigger the background event queue to process our background event message.
         // If any error is happening inside the rebalance callbacks, we expect the first exception to be thrown from poll.
-        if (expectedException.isPresent()) {
-            Exception exception = assertThrows(expectedException.get().getClass(), () -> consumer.poll(Duration.ZERO));
-            assertEquals(expectedException.get().getMessage(), exception.getMessage());
-            assertEquals(expectedException.get().getCause(), exception.getCause());
+        if (expectedExceptionOpt.isPresent()) {
+            Exception expectedException = expectedExceptionOpt.get();
+            ConsumerPollTestUtils.waitForException(
+                consumer,
+                t -> Objects.equals(t.getClass(), expectedException.getClass()) &&
+                    Objects.equals(t.getMessage(), expectedException.getMessage()) &&
+                    Objects.equals(t.getCause(), expectedException.getCause()),
+                "Consumer.poll() did not throw the expected exception " + expectedException
+            );
         } else {
             when(applicationEventHandler.addAndGet(any(CheckAndUpdatePositionsEvent.class))).thenReturn(true);
             assertDoesNotThrow(() -> consumer.poll(Duration.ZERO));
@@ -1543,10 +1557,12 @@ public class AsyncKafkaConsumerTest {
         backgroundEventQueue.add(errorEvent);
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singletonList(new TopicPartition("topic", 0)));
-        markReconcileAndAutoCommitCompleteForPollEvent();
-        final KafkaException exception = assertThrows(KafkaException.class, () -> consumer.poll(Duration.ZERO));
-
-        assertEquals(expectedException.getMessage(), exception.getMessage());
+        completeAsyncPollEventSuccessfully();
+        ConsumerPollTestUtils.waitForException(
+            consumer,
+            t -> t.getMessage().equals(expectedException.getMessage()),
+            "Consumer.poll() did not fail with expected exception " + expectedException + " within timeout"
+        );
     }
 
     @Test
@@ -1562,10 +1578,12 @@ public class AsyncKafkaConsumerTest {
         backgroundEventQueue.add(errorEvent2);
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singletonList(new TopicPartition("topic", 0)));
-        markReconcileAndAutoCommitCompleteForPollEvent();
-        final KafkaException exception = assertThrows(KafkaException.class, () -> consumer.poll(Duration.ZERO));
-
-        assertEquals(expectedException1.getMessage(), exception.getMessage());
+        completeAsyncPollEventSuccessfully();
+        ConsumerPollTestUtils.waitForException(
+            consumer,
+            t -> t.getMessage().equals(expectedException1.getMessage()),
+            "Consumer.poll() did not fail with expected exception " + expectedException1 + " within timeout"
+        );
         assertTrue(backgroundEventQueue.isEmpty());
     }
 
@@ -1645,10 +1663,9 @@ public class AsyncKafkaConsumerTest {
 
         completeTopicSubscriptionChangeEventSuccessfully();
         consumer.subscribe(singletonList("topic1"));
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         consumer.poll(Duration.ofMillis(100));
-        verify(applicationEventHandler).add(any(PollEvent.class));
-        verify(applicationEventHandler).add(any(CreateFetchRequestsEvent.class));
+        verify(applicationEventHandler, atLeastOnce()).add(any(AsyncPollEvent.class));
     }
 
     private Properties requiredConsumerConfigAndGroupId(final String groupId) {
@@ -1664,11 +1681,8 @@ public class AsyncKafkaConsumerTest {
 
         completeAssignmentChangeEventSuccessfully();
         consumer.assign(singleton(new TopicPartition("t1", 1)));
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         consumer.poll(Duration.ZERO);
-
-        verify(applicationEventHandler, atLeast(1))
-            .addAndGet(ArgumentMatchers.isA(CheckAndUpdatePositionsEvent.class));
     }
 
     @Test
@@ -1701,7 +1715,7 @@ public class AsyncKafkaConsumerTest {
         ).when(fetchCollector).collectFetch(any(FetchBuffer.class));
         when(applicationEventHandler.addAndGet(any(CheckAndUpdatePositionsEvent.class))).thenReturn(true);
 
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         // And then poll for up to 10000ms, which should return 2 records without timing out
         ConsumerRecords<?, ?> returnedRecords = consumer.poll(Duration.ofMillis(10000));
         assertEquals(2, returnedRecords.count());
@@ -1805,7 +1819,7 @@ public class AsyncKafkaConsumerTest {
         // interrupt the thread and call poll
         try {
             Thread.currentThread().interrupt();
-            markReconcileAndAutoCommitCompleteForPollEvent();
+            completeAsyncPollEventSuccessfully();
             assertThrows(InterruptException.class, () -> consumer.poll(Duration.ZERO));
         } finally {
             // clear interrupted state again since this thread may be reused by JUnit
@@ -1837,8 +1851,13 @@ public class AsyncKafkaConsumerTest {
         completeTopicSubscriptionChangeEventSuccessfully();
         consumer.subscribe(Collections.singletonList("topic"));
         when(applicationEventHandler.addAndGet(any(CheckAndUpdatePositionsEvent.class))).thenReturn(true);
-        markReconcileAndAutoCommitCompleteForPollEvent();
-        consumer.poll(Duration.ZERO);
+        completeAsyncPollEventSuccessfully();
+
+        ConsumerPollTestUtils.waitForCondition(
+            consumer,
+            () -> backgroundEventReaper.size() == 0,
+            "Consumer.poll() did not reap background events within timeout"
+        );
         verify(backgroundEventReaper).reap(time.milliseconds());
     }
 
@@ -1900,7 +1919,7 @@ public class AsyncKafkaConsumerTest {
         completeUnsubscribeApplicationEventSuccessfully();
 
         consumer.assign(singleton(new TopicPartition("topic1", 0)));
-        markReconcileAndAutoCommitCompleteForPollEvent();
+        completeAsyncPollEventSuccessfully();
         consumer.poll(Duration.ZERO);
         verify(applicationEventHandler, never()).addAndGet(any(UpdatePatternSubscriptionEvent.class));
 
@@ -1908,7 +1927,6 @@ public class AsyncKafkaConsumerTest {
 
         consumer.subscribe(Pattern.compile("t*"));
         consumer.poll(Duration.ZERO);
-        verify(applicationEventHandler).addAndGet(any(UpdatePatternSubscriptionEvent.class));
     }
 
     @Test
@@ -2275,11 +2293,11 @@ public class AsyncKafkaConsumerTest {
         }
     }
 
-    private void markReconcileAndAutoCommitCompleteForPollEvent() {
+    private void completeAsyncPollEventSuccessfully() {
         doAnswer(invocation -> {
-            PollEvent event = invocation.getArgument(0);
-            event.markReconcileAndAutoCommitComplete();
+            AsyncPollEvent event = invocation.getArgument(0);
+            event.completeSuccessfully();
             return null;
-        }).when(applicationEventHandler).add(ArgumentMatchers.isA(PollEvent.class));
+        }).when(applicationEventHandler).add(ArgumentMatchers.isA(AsyncPollEvent.class));
     }
 }

clients/src/test/java/org/apache/kafka/clients/consumer/internals/ConsumerNetworkThreadTest.java

@@ -18,8 +18,8 @@ package org.apache.kafka.clients.consumer.internals;
 
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ApplicationEventProcessor;
+import org.apache.kafka.clients.consumer.internals.events.AsyncPollEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.metrics.AsyncConsumerMetrics;
 import org.apache.kafka.common.KafkaException;
 import org.apache.kafka.common.metrics.Metrics;
@@ -258,7 +258,7 @@ public class ConsumerNetworkThreadTest {
              )) {
             consumerNetworkThread.initializeResources();
 
-            PollEvent event = new PollEvent(0);
+            AsyncPollEvent event = new AsyncPollEvent(10, 0);
             event.setEnqueuedMs(time.milliseconds());
             applicationEventQueue.add(event);
             asyncConsumerMetrics.recordApplicationEventQueueSize(1);

clients/src/test/java/org/apache/kafka/clients/consumer/internals/ShareConsumerImplTest.java

@@ -24,11 +24,11 @@ import org.apache.kafka.clients.consumer.internals.events.ApplicationEventHandle
 import org.apache.kafka.clients.consumer.internals.events.BackgroundEvent;
 import org.apache.kafka.clients.consumer.internals.events.CompletableEventReaper;
 import org.apache.kafka.clients.consumer.internals.events.ErrorEvent;
-import org.apache.kafka.clients.consumer.internals.events.PollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgeOnCloseEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgementCommitCallbackEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareAcknowledgementCommitCallbackRegistrationEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareFetchEvent;
+import org.apache.kafka.clients.consumer.internals.events.SharePollEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareSubscriptionChangeEvent;
 import org.apache.kafka.clients.consumer.internals.events.ShareUnsubscribeEvent;
 import org.apache.kafka.clients.consumer.internals.events.StopFindCoordinatorOnCloseEvent;
@@ -680,7 +680,7 @@ public class ShareConsumerImplTest {
         consumer.subscribe(subscriptionTopic);
 
         consumer.poll(Duration.ofMillis(100));
-        verify(applicationEventHandler).add(any(PollEvent.class));
+        verify(applicationEventHandler).add(any(SharePollEvent.class));
         verify(applicationEventHandler).addAndGet(any(ShareSubscriptionChangeEvent.class));
 
         completeShareAcknowledgeOnCloseApplicationEventSuccessfully();

clients/src/test/java/org/apache/kafka/clients/consumer/internals/events/ApplicationEventProcessorTest.java

@@ -171,7 +171,7 @@ public class ApplicationEventProcessorTest {
 
     private static Stream<Arguments> applicationEvents() {
         return Stream.of(
-                Arguments.of(new PollEvent(100)),
+                Arguments.of(new AsyncPollEvent(calculateDeadlineMs(12345, 100), 100)),
                 Arguments.of(new CreateFetchRequestsEvent(calculateDeadlineMs(12345, 100))),
                 Arguments.of(new CheckAndUpdatePositionsEvent(500)),
                 Arguments.of(new TopicMetadataEvent("topic", Long.MAX_VALUE)),
@@ -265,12 +265,12 @@ public class ApplicationEventProcessorTest {
 
     @Test
     public void testPollEvent() {
-        PollEvent event = new PollEvent(12345);
+        AsyncPollEvent event = new AsyncPollEvent(12346, 12345);
 
         setupProcessor(true);
         when(heartbeatRequestManager.membershipManager()).thenReturn(membershipManager);
+        when(offsetsRequestManager.updateFetchPositions(anyLong())).thenReturn(new CompletableFuture<>());
         processor.process(event);
-        assertTrue(event.reconcileAndAutoCommit().isDone());
         verify(commitRequestManager).updateTimerAndMaybeCommit(12345);
         verify(membershipManager).onConsumerPoll();
         verify(heartbeatRequestManager).resetPollTimer(12345);

core/src/test/scala/integration/kafka/api/AuthorizerIntegrationTest.scala

@@ -1358,7 +1358,7 @@ class AuthorizerIntegrationTest extends AbstractAuthorizerIntegrationTest {
 
     val consumer = createConsumer()
     consumer.assign(java.util.List.of(tp))
-    assertThrows(classOf[TopicAuthorizationException], () => consumeRecords(consumer))
+    assertThrows(classOf[AuthorizationException], () => consumeRecords(consumer))
   }
 
   @ParameterizedTest(name = TestInfoUtils.TestWithParameterizedGroupProtocolNames)

core/src/test/scala/integration/kafka/api/PlaintextAdminIntegrationTest.scala

@@ -35,7 +35,7 @@ import org.apache.kafka.clients.admin.AlterConfigOp.OpType
 import org.apache.kafka.clients.admin.ConfigEntry.ConfigSource
 import org.apache.kafka.clients.admin._
 import org.apache.kafka.clients.consumer.internals.AsyncKafkaConsumer
-import org.apache.kafka.clients.consumer.{CommitFailedException, Consumer, ConsumerConfig, GroupProtocol, KafkaConsumer, OffsetAndMetadata, ShareConsumer}
+import org.apache.kafka.clients.consumer.{CommitFailedException, Consumer, ConsumerConfig, ConsumerRecords, GroupProtocol, KafkaConsumer, OffsetAndMetadata, ShareConsumer}
 import org.apache.kafka.clients.producer.{KafkaProducer, ProducerConfig, ProducerRecord}
 import org.apache.kafka.common.acl.{AccessControlEntry, AclBinding, AclBindingFilter, AclOperation, AclPermissionType}
 import org.apache.kafka.common.config.{ConfigResource, LogLevelConfig, SslConfigs, TopicConfig}
@@ -568,8 +568,15 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
       try {
         consumer.assign(util.Set.of(tp))
         consumer.seekToBeginning(util.Set.of(tp))
-        val records = consumer.poll(time.Duration.ofSeconds(3))
-        assertEquals(expectedNumber, records.count())
+        def verifyRecordCount(records: ConsumerRecords[Array[Byte], Array[Byte]]): Boolean = {
+          expectedNumber == records.count()
+        }
+        TestUtils.pollRecordsUntilTrue(
+          consumer,
+          verifyRecordCount,
+          s"Consumer.poll() did not return the expected number of records ($expectedNumber) within the timeout",
+          pollTimeoutMs = 3000
+        )
       } finally consumer.close()
     }
 
@@ -4585,7 +4592,9 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
     prepareRecords(testTopicName)
 
     // Producer sends messages
-    for (i <- 1 to 20) {
+    val numRecords = 20
+
+    for (i <- 1 to numRecords) {
       TestUtils.waitUntilTrue(() => {
         val producerRecord = producer.send(
             new ProducerRecord[Array[Byte], Array[Byte]](testTopicName, s"key-$i".getBytes(), s"value-$i".getBytes()))
@@ -4594,18 +4603,28 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
       }, "Fail to produce record to topic")
     }
 
+    val consumerConfig = new Properties();
+    consumerConfig.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest")
+
     val streams = createStreamsGroup(
+      configOverrides = consumerConfig,
       inputTopic = testTopicName,
       streamsGroupId = streamsGroupId,
     )
 
     try {
-      TestUtils.waitUntilTrue(() => {
-        streams.poll(JDuration.ofMillis(100L))
-        !streams.assignment().isEmpty
-      }, "Consumer not assigned to partitions")
+      var counter = 0
+
+      def verifyRecordCount(records: ConsumerRecords[Nothing, Nothing]): Boolean = {
+        counter += records.count()
+        counter >= numRecords
+      }
+      TestUtils.pollRecordsUntilTrue(
+        streams,
+        verifyRecordCount,
+        s"Consumer not assigned to partitions"
+      )
 
-      streams.poll(JDuration.ofMillis(1000L))
       streams.commitSync()
 
       TestUtils.waitUntilTrue(() => {
@@ -4645,7 +4664,9 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
     prepareTopics(List(testTopicName), testNumPartitions)
     prepareRecords(testTopicName)
     // Producer sends messages
-    for (i <- 1 to 20) {
+    val numRecords = 20
+
+    for (i <- 1 to numRecords) {
       TestUtils.waitUntilTrue(() => {
         val producerRecord = producer.send(
             new ProducerRecord[Array[Byte], Array[Byte]](testTopicName, s"key-$i".getBytes(), s"value-$i".getBytes()))
@@ -4654,18 +4675,28 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
       }, "Fail to produce record to topic")
     }
 
+    val consumerConfig = new Properties();
+    consumerConfig.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest")
+
     val streams = createStreamsGroup(
+      configOverrides = consumerConfig,
       inputTopic = testTopicName,
       streamsGroupId = streamsGroupId,
     )
 
     try {
-      TestUtils.waitUntilTrue(() => {
-        streams.poll(JDuration.ofMillis(100L))
-        !streams.assignment().isEmpty
-      }, "Consumer not assigned to partitions")
+      var counter = 0
+
+      def verifyRecordCount(records: ConsumerRecords[Nothing, Nothing]): Boolean = {
+        counter += records.count()
+        counter >= numRecords
+      }
+      TestUtils.pollRecordsUntilTrue(
+        streams,
+        verifyRecordCount,
+        s"Consumer not assigned to partitions"
+      )
 
-      streams.poll(JDuration.ofMillis(1000L))
       streams.commitSync()
 
       // List streams group offsets
@@ -4722,7 +4753,9 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
     prepareRecords(testTopicName)
 
     // Producer sends messages
-    for (i <- 1 to 20) {
+    val numRecords = 20
+
+    for (i <- 1 to numRecords) {
       TestUtils.waitUntilTrue(() => {
         val producerRecord = producer.send(
             new ProducerRecord[Array[Byte], Array[Byte]](testTopicName, s"key-$i".getBytes(), s"value-$i".getBytes()))
@@ -4731,18 +4764,28 @@ class PlaintextAdminIntegrationTest extends BaseAdminIntegrationTest {
       }, "Fail to produce record to topic")
     }
 
+    val consumerConfig = new Properties();
+    consumerConfig.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest")
+
     val streams = createStreamsGroup(
+      configOverrides = consumerConfig,
       inputTopic = testTopicName,
       streamsGroupId = streamsGroupId,
     )
 
     try {
-      TestUtils.waitUntilTrue(() => {
-        streams.poll(JDuration.ofMillis(100L))
-        !streams.assignment().isEmpty
-      }, "Consumer not assigned to partitions")
+      var counter = 0
+
+      def verifyRecordCount(records: ConsumerRecords[Nothing, Nothing]): Boolean = {
+        counter += records.count()
+        counter >= numRecords
+      }
+      TestUtils.pollRecordsUntilTrue(
+        streams,
+        verifyRecordCount,
+        s"Consumer not assigned to partitions"
+      )
 
-      streams.poll(JDuration.ofMillis(1000L))
       streams.commitSync()
 
       // List streams group offsets

core/src/test/scala/integration/kafka/api/SaslClientsWithInvalidCredentialsTest.scala

@@ -145,13 +145,27 @@ class SaslClientsWithInvalidCredentialsTest extends AbstractSaslTest {
   }
 
   private def verifyConsumerWithAuthenticationFailure(consumer: Consumer[Array[Byte], Array[Byte]]): Unit = {
-    verifyAuthenticationException(consumer.poll(Duration.ofMillis(1000)))
+    val startMs = System.currentTimeMillis
+    TestUtils.pollUntilException(
+      consumer,
+      _ => true,
+      s"Consumer.poll() did not throw an exception within the timeout",
+      pollTimeoutMs = 1000
+    )
+    val elapsedMs = System.currentTimeMillis - startMs
+    assertTrue(elapsedMs <= 5000, s"Poll took too long, elapsed=$elapsedMs")
     verifyAuthenticationException(consumer.partitionsFor(topic))
 
     createClientCredential()
     val producer = createProducer()
     verifyWithRetry(sendOneRecord(producer))()
-    verifyWithRetry(consumer.poll(Duration.ofMillis(1000)))(_.count == 1)
+    TestUtils.waitUntilTrue(() => {
+      try {
+        consumer.poll(Duration.ofMillis(1000)).count() == 1
+      } catch {
+        case _:Throwable => false
+      }
+    }, msg = s"Consumer.poll() did not read the expected number of records within the timeout")
   }
 
   @Test

core/src/test/scala/integration/kafka/server/GssapiAuthenticationTest.scala

@@ -19,7 +19,6 @@
 package kafka.server
 
 import java.net.InetSocketAddress
-import java.time.Duration
 import java.util.Properties
 import java.util.concurrent.{CountDownLatch, Executors, TimeUnit}
 import javax.security.auth.login.LoginContext
@@ -185,7 +184,12 @@ class GssapiAuthenticationTest extends IntegrationTestHarness with SaslSetup {
     consumer.assign(java.util.List.of(tp))
 
     val startMs = System.currentTimeMillis()
-    assertThrows(classOf[SaslAuthenticationException], () => consumer.poll(Duration.ofMillis(50)))
+    TestUtils.pollUntilException(
+      consumer,
+      t => t.isInstanceOf[SaslAuthenticationException],
+      "Consumer.poll() did not trigger a SaslAuthenticationException within timeout",
+      pollTimeoutMs = 50
+    )
     val endMs = System.currentTimeMillis()
     require(endMs - startMs < failedAuthenticationDelayMs, "Failed authentication must not be delayed on the client")
     consumer.close()

core/src/test/scala/unit/kafka/utils/TestUtils.scala

@@ -690,6 +690,21 @@ object TestUtils extends Logging {
     }, msg = msg, pause = 0L, waitTimeMs = waitTimeMs)
   }
 
+  def pollUntilException(consumer: Consumer[_, _],
+                         action: Throwable => Boolean,
+                         msg: => String,
+                         waitTimeMs: Long = JTestUtils.DEFAULT_MAX_WAIT_MS,
+                         pollTimeoutMs: Long = 100): Unit = {
+    waitUntilTrue(() => {
+      try {
+        consumer.poll(Duration.ofMillis(pollTimeoutMs))
+        false
+      } catch {
+        case t: Throwable => action(t)
+      }
+    }, msg = msg, pause = 0L, waitTimeMs = waitTimeMs)
+  }
+
   def pollRecordsUntilTrue[K, V](consumer: Consumer[K, V],
                                  action: ConsumerRecords[K, V] => Boolean,
                                  msg: => String,

server/src/test/java/org/apache/kafka/server/ReconfigurableQuorumIntegrationTest.java

@@ -15,13 +15,16 @@
  * limitations under the License.
  */
 
-package kafka.server;
+package org.apache.kafka.server;
 
+import org.apache.kafka.clients.admin.AddRaftVoterOptions;
 import org.apache.kafka.clients.admin.Admin;
 import org.apache.kafka.clients.admin.FeatureMetadata;
 import org.apache.kafka.clients.admin.QuorumInfo;
 import org.apache.kafka.clients.admin.RaftVoterEndpoint;
+import org.apache.kafka.clients.admin.RemoveRaftVoterOptions;
 import org.apache.kafka.common.Uuid;
+import org.apache.kafka.common.errors.InconsistentClusterIdException;
 import org.apache.kafka.common.test.KafkaClusterTestKit;
 import org.apache.kafka.common.test.TestKitNodes;
 import org.apache.kafka.common.test.api.TestKitDefaults;
@@ -29,10 +32,12 @@ import org.apache.kafka.raft.QuorumConfig;
 import org.apache.kafka.server.common.KRaftVersion;
 import org.apache.kafka.test.TestUtils;
 
+import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
 
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Set;
 import java.util.TreeMap;
 
@@ -41,6 +46,7 @@ import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertNotEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+@Tag("integration")
 public class ReconfigurableQuorumIntegrationTest {
     static void checkKRaftVersions(Admin admin, short finalized) throws Exception {
         FeatureMetadata featureMetadata = admin.describeFeatures().featureMetadata().get();
@@ -70,7 +76,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ).build()) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, () -> {
                     checkKRaftVersions(admin, KRaftVersion.KRAFT_VERSION_0.featureLevel());
                 });
@@ -88,7 +94,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ).setStandalone(true).build()) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, () -> {
                     checkKRaftVersions(admin, KRaftVersion.KRAFT_VERSION_1.featureLevel());
                 });
@@ -126,7 +132,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
                     Map<Integer, Uuid> voters = findVoterDirs(admin);
                     assertEquals(Set.of(3000, 3001, 3002), voters.keySet());
@@ -161,7 +167,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
                     Map<Integer, Uuid> voters = findVoterDirs(admin);
                     assertEquals(Set.of(3000, 3001, 3002, 3003), voters.keySet());
@@ -200,7 +206,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
                     Map<Integer, Uuid> voters = findVoterDirs(admin);
                     assertEquals(Set.of(3000, 3001, 3002), voters.keySet());
@@ -238,7 +244,7 @@ public class ReconfigurableQuorumIntegrationTest {
         ) {
             cluster.format();
             cluster.startup();
-            try (Admin admin = Admin.create(cluster.clientProperties())) {
+            try (var admin = Admin.create(cluster.clientProperties())) {
                 TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
                     Map<Integer, Uuid> voters = findVoterDirs(admin);
                     assertEquals(Set.of(3000, 3001, 3002), voters.keySet());
@@ -249,4 +255,95 @@ public class ReconfigurableQuorumIntegrationTest {
             }
         }
     }
-}
+
+    @Test
+    public void testRemoveAndAddVoterWithValidClusterId() throws Exception {
+        final var nodes = new TestKitNodes.Builder()
+            .setClusterId("test-cluster")
+            .setNumBrokerNodes(1)
+            .setNumControllerNodes(3)
+            .build();
+
+        final Map<Integer, Uuid> initialVoters = new HashMap<>();
+        for (final var controllerNode : nodes.controllerNodes().values()) {
+            initialVoters.put(
+                controllerNode.id(),
+                controllerNode.metadataDirectoryId()
+            );
+        }
+
+        try (var cluster = new KafkaClusterTestKit.Builder(nodes).setInitialVoterSet(initialVoters).build()) {
+            cluster.format();
+            cluster.startup();
+            try (var admin = Admin.create(cluster.clientProperties())) {
+                TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
+                    Map<Integer, Uuid> voters = findVoterDirs(admin);
+                    assertEquals(Set.of(3000, 3001, 3002), voters.keySet());
+                    for (int replicaId : new int[] {3000, 3001, 3002}) {
+                        assertNotEquals(Uuid.ZERO_UUID, voters.get(replicaId));
+                    }
+                });
+
+                Uuid dirId = cluster.nodes().controllerNodes().get(3000).metadataDirectoryId();
+                admin.removeRaftVoter(
+                    3000,
+                    dirId,
+                    new RemoveRaftVoterOptions().setClusterId(Optional.of("test-cluster"))
+                ).all().get();
+                TestUtils.retryOnExceptionWithTimeout(30_000, 10, () -> {
+                    Map<Integer, Uuid> voters = findVoterDirs(admin);
+                    assertEquals(Set.of(3001, 3002), voters.keySet());
+                    for (int replicaId : new int[] {3001, 3002}) {
+                        assertNotEquals(Uuid.ZERO_UUID, voters.get(replicaId));
+                    }
+                });
+
+                admin.addRaftVoter(
+                    3000,
+                    dirId,
+                    Set.of(new RaftVoterEndpoint("CONTROLLER", "example.com", 8080)),
+                    new AddRaftVoterOptions().setClusterId(Optional.of("test-cluster"))
+                ).all().get();
+            }
+        }
+    }
+
+    @Test
+    public void testRemoveAndAddVoterWithInconsistentClusterId() throws Exception {
+        final var nodes = new TestKitNodes.Builder()
+            .setClusterId("test-cluster")
+            .setNumBrokerNodes(1)
+            .setNumControllerNodes(3)
+            .build();
+
+        final Map<Integer, Uuid> initialVoters = new HashMap<>();
+        for (final var controllerNode : nodes.controllerNodes().values()) {
+            initialVoters.put(
+                controllerNode.id(),
+                controllerNode.metadataDirectoryId()
+            );
+        }
+
+        try (var cluster = new KafkaClusterTestKit.Builder(nodes).setInitialVoterSet(initialVoters).build()) {
+            cluster.format();
+            cluster.startup();
+            try (var admin = Admin.create(cluster.clientProperties())) {
+                Uuid dirId = cluster.nodes().controllerNodes().get(3000).metadataDirectoryId();
+                var removeFuture = admin.removeRaftVoter(
+                    3000,
+                    dirId,
+                    new RemoveRaftVoterOptions().setClusterId(Optional.of("inconsistent"))
+                ).all();
+                TestUtils.assertFutureThrows(InconsistentClusterIdException.class, removeFuture);
+
+                var addFuture = admin.addRaftVoter(
+                    3000,
+                    dirId,
+                    Set.of(new RaftVoterEndpoint("CONTROLLER", "example.com", 8080)),
+                    new AddRaftVoterOptions().setClusterId(Optional.of("inconsistent"))
+                ).all();
+                TestUtils.assertFutureThrows(InconsistentClusterIdException.class, addFuture);
+            }
+        }
+    }
+}