Gh 3340

spring-kafka-docs/src/main/antora/modules/ROOT/pages/kafka/events.adoc

@@ -23,6 +23,7 @@ See xref:kafka/thread-safety.adoc[Thread Safety].
 * `ConsumerRetryAuthEvent`: published when authentication or authorization of a consumer fails and is being retried.
 * `ConsumerRetryAuthSuccessfulEvent`: published when authentication or authorization has been retried successfully. Can only occur when there has been a `ConsumerRetryAuthEvent` before.
 * `ContainerStoppedEvent`: published when all consumers have stopped.
+* `ConcurrentContainerStoppedEvent`: published when the `ConcurrentMessageListenerContainer` has stopped.
 
 IMPORTANT: By default, the application context's event multicaster invokes event listeners on the calling thread.
 If you change the multicaster to use an async executor, you must not invoke any `Consumer` methods when the event contains a reference to the consumer.

spring-kafka-docs/src/main/antora/modules/ROOT/pages/whats-new.adoc

@@ -19,4 +19,8 @@ A new method, `getGroupId()`, has been added to the `ConsumerSeekCallback` inter
 This method allows for more selective seek operations by targeting only the desired consumer group.
 For more details, see xref:kafka/seek.adoc#seek[Seek API Docs].
 
+[x33-concurrent-container-stopped-event]]
+=== ConcurrentContainerStoppedEvent
+
+The `ConcurentContainerMessageListenerContainer` emits now a `ConcurrentContainerStoppedEvent` when all of its child containers are stopped.
 

spring-kafka/src/main/java/org/springframework/kafka/event/ConcurrentContainerStoppedEvent.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2018-2024 the original author or authors.
+ *
+ * Licensed 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
+ *
+ *      https://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.springframework.kafka.event;
+
+/**
+ * An event published when a concurrent container is stopped.
+ *
+ * @author Lokesh Alamuri
+ * @since 3.3
+ *
+ */
+public class ConcurrentContainerStoppedEvent extends KafkaEvent {
+
+	private static final long serialVersionUID = 1L;
+
+	/**
+	 * Construct an instance with the provided source and container.
+	 * @param source the container instance that generated the event.
+	 */
+	public ConcurrentContainerStoppedEvent(Object source) {
+		super(source, source);
+	}
+
+	@Override
+	public String toString() {
+		return "ConcurrentContainerStoppedEvent [source=" + getSource() + "]";
+	}
+
+}

spring-kafka/src/main/java/org/springframework/kafka/listener/ConcurrentMessageListenerContainer.java

@@ -35,6 +35,7 @@
 import org.springframework.core.task.AsyncTaskExecutor;
 import org.springframework.core.task.SimpleAsyncTaskExecutor;
 import org.springframework.kafka.core.ConsumerFactory;
+import org.springframework.kafka.event.ConcurrentContainerStoppedEvent;
 import org.springframework.kafka.event.ConsumerStoppedEvent.Reason;
 import org.springframework.kafka.support.TopicPartitionOffset;
 import org.springframework.lang.Nullable;
@@ -65,7 +66,7 @@ public class ConcurrentMessageListenerContainer<K, V> extends AbstractMessageLis
 
 	private final List<AsyncTaskExecutor> executors = new ArrayList<>();
 
-	private final AtomicInteger stoppedContainers = new AtomicInteger();
+	private final AtomicInteger startedContainers = new AtomicInteger();
 
 	private int concurrency = 1;
 
@@ -243,6 +244,7 @@ protected void doStart() {
 						+ topicPartitions.length);
 				this.concurrency = topicPartitions.length;
 			}
+			this.startedContainers.set(0);
 			setRunning(true);
 
 			for (int i = 0; i < this.concurrency; i++) {
@@ -374,24 +376,38 @@ protected void doStop(final Runnable callback, boolean normal) {
 		}
 	}
 
+	@Override
+	public void childStarted(MessageListenerContainer child) {
+		this.startedContainers.incrementAndGet();
+	}
+
 	@Override
 	public void childStopped(MessageListenerContainer child, Reason reason) {
 		if (this.reason == null || reason.equals(Reason.AUTH)) {
 			this.reason = reason;
 		}
-		if (Reason.AUTH.equals(this.reason)
-				&& getContainerProperties().isRestartAfterAuthExceptions()
-				&& this.concurrency == this.stoppedContainers.incrementAndGet()) {
+		int startedContainersCount = this.startedContainers.decrementAndGet();
+		if (startedContainersCount == 0) {
+			publishConcurrentContainerStoppedEvent();
+			if (Reason.AUTH.equals(this.reason)
+					&& getContainerProperties().isRestartAfterAuthExceptions()) {
 
-			this.reason = null;
-			this.stoppedContainers.set(0);
+				this.reason = null;
 
-			// This has to run on another thread to avoid a deadlock on lifecycleMonitor
-			AsyncTaskExecutor exec = getContainerProperties().getListenerTaskExecutor();
-			if (exec == null) {
-				exec = new SimpleAsyncTaskExecutor(getListenerId() + ".authRestart");
+				// This has to run on another thread to avoid a deadlock on lifecycleMonitor
+				AsyncTaskExecutor exec = getContainerProperties().getListenerTaskExecutor();
+				if (exec == null) {
+					exec = new SimpleAsyncTaskExecutor(getListenerId() + ".authRestart");
+				}
+				exec.execute(this::start);
 			}
-			exec.execute(this::start);
+		}
+	}
+
+	private void publishConcurrentContainerStoppedEvent() {
+		ApplicationEventPublisher eventPublisher = getApplicationEventPublisher();
+		if (eventPublisher != null) {
+			eventPublisher.publishEvent(new ConcurrentContainerStoppedEvent(this));
 		}
 	}
 

spring-kafka/src/main/java/org/springframework/kafka/listener/KafkaMessageListenerContainer.java

@@ -378,6 +378,7 @@ protected void doStart() {
 			}
 		}
 		this.listenerConsumer = new ListenerConsumer(listener, listenerType, observationRegistry);
+		this.thisOrParentContainer.childStarted(this);
 		setRunning(true);
 		this.startLatch = new CountDownLatch(1);
 		this.listenerConsumerFuture = consumerExecutor.submitCompletable(this.listenerConsumer);

spring-kafka/src/main/java/org/springframework/kafka/listener/MessageListenerContainer.java

@@ -281,6 +281,14 @@ default MessageListenerContainer getContainerFor(String topic, int partition) {
 	default void childStopped(MessageListenerContainer child, ConsumerStoppedEvent.Reason reason) {
 	}
 
+	/**
+	 * Notify a parent container that a child container has started.
+	 * @param child the container.
+	 * @since 3.3
+	 */
+	default void childStarted(MessageListenerContainer child) {
+	}
+
 	@Override
 	default void destroy() {
 		stop();

spring-kafka/src/test/java/org/springframework/kafka/listener/ConcurrentMessageListenerContainerTests.java

@@ -59,6 +59,7 @@
 import org.springframework.kafka.core.DefaultKafkaProducerFactory;
 import org.springframework.kafka.core.KafkaTemplate;
 import org.springframework.kafka.core.ProducerFactory;
+import org.springframework.kafka.event.ConcurrentContainerStoppedEvent;
 import org.springframework.kafka.event.ContainerStoppedEvent;
 import org.springframework.kafka.event.KafkaEvent;
 import org.springframework.kafka.support.TopicPartitionOffset;
@@ -157,11 +158,15 @@ protected Consumer<Integer, String> createKafkaConsumer(String groupId, String c
 		container.setChangeConsumerThreadName(true);
 		BlockingQueue<KafkaEvent> events = new LinkedBlockingQueue<>();
 		CountDownLatch stopLatch = new CountDownLatch(4);
+		CountDownLatch concurrentContainerStopLatch = new CountDownLatch(1);
 		container.setApplicationEventPublisher(e -> {
 			events.add((KafkaEvent) e);
 			if (e instanceof ContainerStoppedEvent) {
 				stopLatch.countDown();
 			}
+			if (e instanceof ConcurrentContainerStoppedEvent) {
+				concurrentContainerStopLatch.countDown();
+			}
 		});
 		CountDownLatch intercepted = new CountDownLatch(4);
 		container.setRecordInterceptor((record, consumer) -> {
@@ -205,6 +210,7 @@ protected Consumer<Integer, String> createKafkaConsumer(String groupId, String c
 		container.getContainers().get(0).start();
 		container.stop();
 		assertThat(stopLatch.await(10, TimeUnit.SECONDS)).isTrue();
+		assertThat(concurrentContainerStopLatch.await(10, TimeUnit.SECONDS)).isTrue();
 		assertThat(container.isInExpectedState()).isTrue();
 		events.forEach(e -> {
 			assertThat(e.getContainer(MessageListenerContainer.class)).isSameAs(container);
@@ -216,6 +222,10 @@ protected Consumer<Integer, String> createKafkaConsumer(String groupId, String c
 					assertThat(children).contains((KafkaMessageListenerContainer<Integer, String>) e.getSource());
 				}
 			}
+			else if (e instanceof ConcurrentContainerStoppedEvent) {
+				assertThat(e.getSource()).isSameAs(container);
+				assertThat(e.getContainer(MessageListenerContainer.class)).isSameAs(container);
+			}
 			else {
 				assertThat(children).contains((KafkaMessageListenerContainer<Integer, String>) e.getSource());
 			}