When virtual threads are enabled, configure Pulsar to use them

Closes gh-36347

Author: wilkinsona

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/pulsar/PulsarAutoConfiguration.java

@@ -31,10 +31,13 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.autoconfigure.thread.Threading;
 import org.springframework.boot.util.LambdaSafe;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
+import org.springframework.core.env.Environment;
+import org.springframework.core.task.VirtualThreadTaskExecutor;
 import org.springframework.pulsar.annotation.EnablePulsar;
 import org.springframework.pulsar.config.ConcurrentPulsarListenerContainerFactory;
 import org.springframework.pulsar.config.DefaultPulsarReaderContainerFactory;
@@ -149,10 +152,13 @@ private void applyConsumerBuilderCustomizers(List<ConsumerBuilderCustomizer<?>>
 	@ConditionalOnMissingBean(name = "pulsarListenerContainerFactory")
 	ConcurrentPulsarListenerContainerFactory<Object> pulsarListenerContainerFactory(
 			PulsarConsumerFactory<Object> pulsarConsumerFactory, SchemaResolver schemaResolver,
-			TopicResolver topicResolver) {
+			TopicResolver topicResolver, Environment environment) {
 		PulsarContainerProperties containerProperties = new PulsarContainerProperties();
 		containerProperties.setSchemaResolver(schemaResolver);
 		containerProperties.setTopicResolver(topicResolver);
+		if (Threading.VIRTUAL.isActive(environment)) {
+			containerProperties.setConsumerTaskExecutor(new VirtualThreadTaskExecutor());
+		}
 		this.propertiesMapper.customizeContainerProperties(containerProperties);
 		return new ConcurrentPulsarListenerContainerFactory<>(pulsarConsumerFactory, containerProperties);
 	}
@@ -178,9 +184,12 @@ private void applyReaderBuilderCustomizers(List<ReaderBuilderCustomizer<?>> cust
 	@Bean
 	@ConditionalOnMissingBean(name = "pulsarReaderContainerFactory")
 	DefaultPulsarReaderContainerFactory<?> pulsarReaderContainerFactory(PulsarReaderFactory<?> pulsarReaderFactory,
-			SchemaResolver schemaResolver) {
+			SchemaResolver schemaResolver, Environment environment) {
 		PulsarReaderContainerProperties readerContainerProperties = new PulsarReaderContainerProperties();
 		readerContainerProperties.setSchemaResolver(schemaResolver);
+		if (Threading.VIRTUAL.isActive(environment)) {
+			readerContainerProperties.setReaderTaskExecutor(new VirtualThreadTaskExecutor());
+		}
 		this.propertiesMapper.customizeReaderContainerProperties(readerContainerProperties);
 		return new DefaultPulsarReaderContainerFactory<>(pulsarReaderFactory, readerContainerProperties);
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/pulsar/PulsarAutoConfigurationTests.java

@@ -29,6 +29,8 @@
 import org.apache.pulsar.common.schema.SchemaType;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 
@@ -39,6 +41,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.annotation.Order;
+import org.springframework.core.task.VirtualThreadTaskExecutor;
 import org.springframework.pulsar.annotation.PulsarBootstrapConfiguration;
 import org.springframework.pulsar.annotation.PulsarListenerAnnotationBeanPostProcessor;
 import org.springframework.pulsar.annotation.PulsarReaderAnnotationBeanPostProcessor;
@@ -464,6 +467,27 @@ void whenObservationsDisabledDoesNotEnableObservation() {
 					.hasFieldOrPropertyWithValue("containerProperties.observationEnabled", false));
 		}
 
+		@Test
+		@EnabledForJreRange(min = JRE.JAVA_21)
+		void whenVirtualThreadsAreEnabledOnJava21AndLaterListenerContainerShouldUseVirtualThreads() {
+			this.contextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run((context) -> {
+				ConcurrentPulsarListenerContainerFactory<?> factory = context
+					.getBean(ConcurrentPulsarListenerContainerFactory.class);
+				assertThat(factory.getContainerProperties().getConsumerTaskExecutor())
+					.isInstanceOf(VirtualThreadTaskExecutor.class);
+			});
+		}
+
+		@Test
+		@EnabledForJreRange(max = JRE.JAVA_20)
+		void whenVirtualThreadsAreEnabledOnJava20AndEarlierListenerContainerShouldNotUseVirtualThreads() {
+			this.contextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run((context) -> {
+				ConcurrentPulsarListenerContainerFactory<?> factory = context
+					.getBean(ConcurrentPulsarListenerContainerFactory.class);
+				assertThat(factory.getContainerProperties().getConsumerTaskExecutor()).isNull();
+			});
+		}
+
 	}
 
 	@Nested
@@ -498,6 +522,27 @@ <T> void whenHasUserDefinedCustomizersAppliesInCorrectOrder() {
 				});
 		}
 
+		@Test
+		@EnabledForJreRange(min = JRE.JAVA_21)
+		void whenVirtualThreadsAreEnabledOnJava21AndLaterReaderShouldUseVirtualThreads() {
+			this.contextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run((context) -> {
+				DefaultPulsarReaderContainerFactory<?> factory = context
+					.getBean(DefaultPulsarReaderContainerFactory.class);
+				assertThat(factory.getContainerProperties().getReaderTaskExecutor())
+					.isInstanceOf(VirtualThreadTaskExecutor.class);
+			});
+		}
+
+		@Test
+		@EnabledForJreRange(max = JRE.JAVA_20)
+		void whenVirtualThreadsAreEnabledOnJava20AndEarlierReaderShouldNotUseVirtualThreads() {
+			this.contextRunner.withPropertyValues("spring.threads.virtual.enabled=true").run((context) -> {
+				DefaultPulsarReaderContainerFactory<?> factory = context
+					.getBean(DefaultPulsarReaderContainerFactory.class);
+				assertThat(factory.getContainerProperties().getReaderTaskExecutor()).isNull();
+			});
+		}
+
 		@TestConfiguration(proxyBeanMethods = false)
 		static class ReaderBuilderCustomizersConfig {