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Original file line number Diff line number Diff line change
@@ -0,0 +1,149 @@
/*
* 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.streams.integration;

import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.common.utils.MockTime;
import org.apache.kafka.streams.KafkaStreams;
import org.apache.kafka.streams.StreamsConfig;
import org.apache.kafka.streams.TopologyWrapper;
import org.apache.kafka.streams.errors.ProcessorStateException;
import org.apache.kafka.streams.integration.utils.EmbeddedKafkaCluster;
import org.apache.kafka.streams.processor.StateStore;
import org.apache.kafka.streams.processor.StateStoreContext;
import org.apache.kafka.streams.state.KeyValueStore;
import org.apache.kafka.streams.state.StoreBuilder;
import org.apache.kafka.streams.state.internals.AbstractStoreBuilder;
import org.apache.kafka.test.MockApiProcessorSupplier;
import org.apache.kafka.test.MockKeyValueStore;
import org.apache.kafka.test.TestUtils;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInfo;

import java.io.IOException;
import java.time.Duration;
import java.util.Properties;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicReference;

import static org.apache.kafka.streams.utils.TestUtils.safeUniqueTestName;
import static org.junit.jupiter.api.Assertions.assertTrue;

public class StateUpdaterFailureIntegrationTest {

private static final int NUM_BROKERS = 1;
protected static final String INPUT_TOPIC_NAME = "input-topic";
private static final int NUM_PARTITIONS = 6;

private final EmbeddedKafkaCluster cluster = new EmbeddedKafkaCluster(NUM_BROKERS);

private Properties streamsConfiguration;
private final MockTime mockTime = cluster.time;
private KafkaStreams streams;

@BeforeEach
public void before(final TestInfo testInfo) throws InterruptedException, IOException {
cluster.start();
cluster.createTopic(INPUT_TOPIC_NAME, NUM_PARTITIONS, 1);
streamsConfiguration = new Properties();
final String safeTestName = safeUniqueTestName(testInfo);
streamsConfiguration.put(StreamsConfig.APPLICATION_ID_CONFIG, "app-" + safeTestName);
streamsConfiguration.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, cluster.bootstrapServers());
streamsConfiguration.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
streamsConfiguration.put(StreamsConfig.STATE_DIR_CONFIG, TestUtils.tempDirectory().getPath());
streamsConfiguration.put(StreamsConfig.STATESTORE_CACHE_MAX_BYTES_CONFIG, 0);
streamsConfiguration.put(StreamsConfig.COMMIT_INTERVAL_MS_CONFIG, 100L);
streamsConfiguration.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.IntegerSerde.class);
streamsConfiguration.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.StringSerde.class);
streamsConfiguration.put(StreamsConfig.NUM_STREAM_THREADS_CONFIG, 2);

}

@AfterEach
public void after() {
cluster.stop();
if (streams != null) {
streams.close(Duration.ofSeconds(30));
}
}

/**
* The conditions that we need to meet:
* <p><ul>
* <li>We have an unhandled task in {@link org.apache.kafka.streams.processor.internals.DefaultStateUpdater}</li>
* <li>StreamThread is not running, so {@link org.apache.kafka.streams.processor.internals.TaskManager#handleExceptionsFromStateUpdater} is not called anymore</li>
* <li>The task throws exception in {@link org.apache.kafka.streams.processor.internals.Task#maybeCheckpoint(boolean)} while being processed by {@code DefaultStateUpdater}</li>
* <li>{@link org.apache.kafka.streams.processor.internals.TaskManager#shutdownStateUpdater} tries to clean up all tasks that are left in the {@code DefaultStateUpdater}</li>
* </ul><p>
* If all conditions are met, {@code TaskManager} needs to be able to handle the failed task from the {@code DefaultStateUpdater} correctly and not hang.
*/
@Test
public void correctlyHandleFlushErrorsDuringRebalance() throws Exception {
final AtomicInteger numberOfStoreInits = new AtomicInteger();
final AtomicReference<KafkaStreams.State> currentState = new AtomicReference<>();

final StoreBuilder<KeyValueStore<Object, Object>> storeBuilder = new AbstractStoreBuilder<>("testStateStore", Serdes.Integer(), Serdes.ByteArray(), new MockTime()) {

@Override
public KeyValueStore<Object, Object> build() {
return new MockKeyValueStore(name, false) {

@Override
public void init(final StateStoreContext stateStoreContext, final StateStore root) {
super.init(stateStoreContext, root);
numberOfStoreInits.incrementAndGet();
}

@Override
public void flush() {
// we want to throw the ProcessorStateException here only when the rebalance finished(we reassigned the 3 tasks from the removed thread to the existing thread)
// we use waitForCondition to wait until the current state is PENDING_SHUTDOWN to make sure the Stream Thread will not handle the exception and we can get to in TaskManager#shutdownStateUpdater
if (numberOfStoreInits.get() == 9) {
try {
TestUtils.waitForCondition(() -> currentState.get() == KafkaStreams.State.PENDING_SHUTDOWN, "Streams never reached PENDING_SHUTDOWN state");
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@mjsax mjsax Nov 6, 2025

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Not sure if I understand this condition. Can you elaborate?

Also: if we fail here, how do we ensure that the test fails? This would be executed on the background StreamsThread not the actual "main" thread running the test.

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to reproduce the issue, we need to fail during a shutdown.

so what the test does:

  • it creates a KS app with 2 threads.
  • then kills one thread which causes a rebalance
  • then the rebalance hangs here, because we can't flush a task.
  • we call streams close
  • this call gets unblocked and throws an exception
  • that's where we reproduce the issue

in other words: the problem I am trying to fix here reproduces if: we are in rebalance, we have some unhandled tasks in the task updater which can throw an exception, which can kill the thread, and we are trying to close the app.
in this case the stream thread will not do its thing, which in turn will not call TaskManager, which will not call stateUpdater.drainExceptionsAndFailedTasks, which will not remove all failed tasks from the lists. which in turn will cause stateUpdater.tasks to return the failed tasks. and TaskManager will try to delete them.
but because the thread is dead, the delete will never succeed, as the dead thread will never complete the future

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I will add a comment to the test to explain what exactly we are trying to achieve here

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I understand that we do want to throw here to trigger an error on the state-updater thread. But it's not clear to me, why we would need to block/wait here until we go to "pending shutdown"?

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what needs to happen to reproduce the issue:
the stream thread is already down(so, we want this condition: https://github.com/apache/kafka/blob/trunk/streams/src/main/java/org/apache/kafka/streams/processor/internals/StreamThread.java#L933 to be false), we also want to have a task in the state updater. and this task needs to throw an exception.

maybe there is an easier way to achieve these conditions, but that's what I was able to come up with

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the stream thread is already down

You mean before the state-updater crashes? Interesting. Not clear to me why though? Can you explain further?

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@Nikita-Shupletsov Nikita-Shupletsov Nov 8, 2025

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before the state-updater crashes

yes. when the stream thread is running it calls StreamThread#checkStateUpdater, which, in turn, calls TaskManager, which calls StateUpdater#drainExceptionsAndFailedTasks.
so it will delete the failed task from the list of tasks(hence StateUpdater#tasks will not return them anymore) and trigger shutdown.
and when we get to the shutdown, we will not have anything in the state updater, so we will not try to remove anything from in the shutdownStateUpdater method, hence we will not get stuck.

it technically can be slightly different: we have some tasks in the state updater, one of them fails and kills the thread, which will be picked up by the stream thread. but if after that we some how add more tasks to the state updater, we will get the same issue.
But I couldn't figure out if it's even possible to add new tasks to the state updater when the thread is shitting down, as it happens only during rebalance(but here I may be wrong)

} catch (final InterruptedException e) {
throw new RuntimeException(e);
}
throw new ProcessorStateException("flush");
}
}
};
}
};

final TopologyWrapper topology = new TopologyWrapper();
topology.addSource("ingest", INPUT_TOPIC_NAME);
topology.addProcessor("my-processor", new MockApiProcessorSupplier<>(), "ingest");
topology.addStateStore(storeBuilder, "my-processor");

streams = new KafkaStreams(topology, streamsConfiguration);
streams.setStateListener((newState, oldState) -> currentState.set(newState));
streams.start();

TestUtils.waitForCondition(() -> currentState.get() == KafkaStreams.State.RUNNING, "Streams never reached RUNNING state");

streams.removeStreamThread();

// Before shutting down, we want the tasks to be reassigned
TestUtils.waitForCondition(() -> numberOfStoreInits.get() == 9, "Streams never reinitialized the store enough times");

assertTrue(streams.close(Duration.ofSeconds(60)));
}
}
Original file line number Diff line number Diff line change
Expand Up @@ -345,23 +345,26 @@ private void handleTaskCorruptedException(final TaskCorruptedException taskCorru
// TODO: we can let the exception encode the actual corrupted changelog partitions and only
// mark those instead of marking all changelogs
private void removeCheckpointForCorruptedTask(final Task task) {
task.markChangelogAsCorrupted(task.changelogPartitions());
try {
task.markChangelogAsCorrupted(task.changelogPartitions());

// we need to enforce a checkpoint that removes the corrupted partitions
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
// we need to enforce a checkpoint that removes the corrupted partitions
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
} catch (final StreamsException swallow) {
log.warn("Checkpoint failed for corrupted task {}", task.id(), swallow);
}
}

private void handleStreamsException(final StreamsException streamsException) {
log.info("Encountered streams exception: ", streamsException);
if (streamsException.taskId().isPresent()) {
handleStreamsExceptionWithTask(streamsException);
handleStreamsExceptionWithTask(streamsException, streamsException.taskId().get());
} else {
handleStreamsExceptionWithoutTask(streamsException);
}
}

private void handleStreamsExceptionWithTask(final StreamsException streamsException) {
final TaskId failedTaskId = streamsException.taskId().get();
private void handleStreamsExceptionWithTask(final StreamsException streamsException, final TaskId failedTaskId) {
if (updatingTasks.containsKey(failedTaskId)) {
addToExceptionsAndFailedTasksThenRemoveFromUpdatingTasks(
new ExceptionAndTask(streamsException, updatingTasks.get(failedTaskId))
Expand Down Expand Up @@ -514,7 +517,7 @@ private void removeTask(final TaskId taskId, final CompletableFuture<RemovedTask
+ " own this task.", taskId);
}
} catch (final StreamsException streamsException) {
handleStreamsException(streamsException);
handleStreamsExceptionWithTask(streamsException, taskId);
future.completeExceptionally(streamsException);
} catch (final RuntimeException runtimeException) {
handleRuntimeException(runtimeException);
Expand Down Expand Up @@ -606,14 +609,19 @@ private boolean removeFailedTask(final TaskId taskId, final CompletableFuture<Re
private void pauseTask(final Task task) {
final TaskId taskId = task.id();
// do not need to unregister changelog partitions for paused tasks
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
pausedTasks.put(taskId, task);
updatingTasks.remove(taskId);
if (task.isActive()) {
transitToUpdateStandbysIfOnlyStandbysLeft();
try {
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
pausedTasks.put(taskId, task);
updatingTasks.remove(taskId);
if (task.isActive()) {
transitToUpdateStandbysIfOnlyStandbysLeft();
}
log.info((task.isActive() ? "Active" : "Standby")
+ " task " + task.id() + " was paused from the updating tasks and added to the paused tasks.");

} catch (final StreamsException streamsException) {
handleStreamsExceptionWithTask(streamsException, taskId);
}
log.info((task.isActive() ? "Active" : "Standby")
+ " task " + task.id() + " was paused from the updating tasks and added to the paused tasks.");
}

private void resumeTask(final Task task) {
Expand All @@ -640,11 +648,15 @@ private void maybeCompleteRestoration(final StreamTask task,
final Set<TopicPartition> restoredChangelogs) {
final Collection<TopicPartition> changelogPartitions = task.changelogPartitions();
if (restoredChangelogs.containsAll(changelogPartitions)) {
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
changelogReader.unregister(changelogPartitions);
addToRestoredTasks(task);
log.info("Stateful active task " + task.id() + " completed restoration");
transitToUpdateStandbysIfOnlyStandbysLeft();
try {
measureCheckpointLatency(() -> task.maybeCheckpoint(true));
changelogReader.unregister(changelogPartitions);
addToRestoredTasks(task);
log.info("Stateful active task " + task.id() + " completed restoration");
transitToUpdateStandbysIfOnlyStandbysLeft();
} catch (final StreamsException streamsException) {
handleStreamsExceptionWithTask(streamsException, task.id());
}
}
}

Expand Down Expand Up @@ -676,8 +688,12 @@ private void maybeCheckpointTasks(final long now) {

measureCheckpointLatency(() -> {
for (final Task task : updatingTasks.values()) {
// do not enforce checkpointing during restoration if its position has not advanced much
task.maybeCheckpoint(false);
try {
// do not enforce checkpointing during restoration if its position has not advanced much
task.maybeCheckpoint(false);
} catch (final StreamsException streamsException) {
handleStreamsExceptionWithTask(streamsException, task.id());
}
}
});

Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,7 @@
import java.util.TreeSet;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.stream.Collectors;
import java.util.stream.Stream;
Expand Down Expand Up @@ -772,7 +773,7 @@ private StateUpdater.RemovedTaskResult waitForFuture(final TaskId taskId,
final CompletableFuture<StateUpdater.RemovedTaskResult> future) {
final StateUpdater.RemovedTaskResult removedTaskResult;
try {
removedTaskResult = future.get();
removedTaskResult = future.get(1, TimeUnit.MINUTES);
if (removedTaskResult == null) {
throw new IllegalStateException("Task " + taskId + " was not found in the state updater. "
+ BUG_ERROR_MESSAGE);
Expand All @@ -787,6 +788,10 @@ private StateUpdater.RemovedTaskResult waitForFuture(final TaskId taskId,
Thread.currentThread().interrupt();
log.error(INTERRUPTED_ERROR_MESSAGE, shouldNotHappen);
throw new IllegalStateException(INTERRUPTED_ERROR_MESSAGE, shouldNotHappen);
} catch (final java.util.concurrent.TimeoutException timeoutException) {
log.warn("The state updater wasn't able to remove task {} in time. The state updater thread may be dead. "
+ BUG_ERROR_MESSAGE, taskId, timeoutException);
return null;
}
}

Expand Down Expand Up @@ -1576,6 +1581,12 @@ void shutdown(final boolean clean) {

private void shutdownStateUpdater() {
if (stateUpdater != null) {
// If there are failed tasks handling them first
for (final StateUpdater.ExceptionAndTask exceptionAndTask : stateUpdater.drainExceptionsAndFailedTasks()) {
final Task failedTask = exceptionAndTask.task();
closeTaskDirty(failedTask, false);
}

final Map<TaskId, CompletableFuture<StateUpdater.RemovedTaskResult>> futures = new LinkedHashMap<>();
for (final Task task : stateUpdater.tasks()) {
final CompletableFuture<StateUpdater.RemovedTaskResult> future = stateUpdater.remove(task.id());
Expand All @@ -1592,10 +1603,16 @@ private void shutdownStateUpdater() {
for (final Task task : tasksToCloseDirty) {
closeTaskDirty(task, false);
}
// Handling all failures that occurred during the remove process
for (final StateUpdater.ExceptionAndTask exceptionAndTask : stateUpdater.drainExceptionsAndFailedTasks()) {
final Task failedTask = exceptionAndTask.task();
closeTaskDirty(failedTask, false);
}

// If there is anything left unhandled due to timeouts, handling now
for (final Task task : stateUpdater.tasks()) {
closeTaskDirty(task, false);
}
}
}

Expand Down
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