Use ConditionalOnThreading and replace Java 21 specific virtual thread check

Author: Mike Turbe

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpMetricsExportAutoConfiguration.java

@@ -30,9 +30,12 @@
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBean;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnThreading;
+import org.springframework.boot.autoconfigure.thread.Threading;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
 import org.springframework.context.annotation.Bean;
 import org.springframework.core.env.Environment;
+import org.springframework.core.task.VirtualThreadTaskExecutor;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for exporting metrics to OTLP.
@@ -72,13 +75,19 @@ OtlpConfig otlpConfig(OpenTelemetryProperties openTelemetryProperties,
 
 	@Bean
 	@ConditionalOnMissingBean
-	public OtlpMeterRegistry otlpMeterRegistry(OtlpConfig otlpConfig, Clock clock) {
-		if (this.properties.isVirtualThreadsEnabled()) {
-			return new OtlpMeterRegistry(otlpConfig, clock, Thread.ofVirtual().factory());
-		}
+	@ConditionalOnThreading(Threading.PLATFORM)
+	public OtlpMeterRegistry otlpMeterRegistryPlatformThreads(OtlpConfig otlpConfig, Clock clock) {
 		return new OtlpMeterRegistry(otlpConfig, clock);
 	}
 
+	@Bean
+	@ConditionalOnMissingBean
+	@ConditionalOnThreading(Threading.VIRTUAL)
+	public OtlpMeterRegistry otlpMeterRegistryVirtualThreads(OtlpConfig otlpConfig, Clock clock) {
+		VirtualThreadTaskExecutor taskExecutor = new VirtualThreadTaskExecutor("otlp-meter-registry");
+		return new OtlpMeterRegistry(otlpConfig, clock, taskExecutor.getVirtualThreadFactory());
+	}
+
 	/**
 	 * Adapts {@link OtlpProperties} to {@link OtlpMetricsConnectionDetails}.
 	 */

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpProperties.java

@@ -151,12 +151,4 @@ public void setBaseTimeUnit(TimeUnit baseTimeUnit) {
 		this.baseTimeUnit = baseTimeUnit;
 	}
 
-	public boolean isVirtualThreadsEnabled() {
-		return this.virtualThreadsEnabled;
-	}
-
-	public void setVirtualThreadsEnabled(boolean virtualThreadsEnabled) {
-		this.virtualThreadsEnabled = virtualThreadsEnabled;
-	}
-
 }

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpMetricsExportAutoConfigurationTests.java

@@ -22,6 +22,8 @@
 import io.micrometer.registry.otlp.OtlpConfig;
 import io.micrometer.registry.otlp.OtlpMeterRegistry;
 import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledForJreRange;
+import org.junit.jupiter.api.condition.JRE;
 
 import org.springframework.boot.actuate.autoconfigure.metrics.export.otlp.OtlpMetricsExportAutoConfiguration.PropertiesOtlpMetricsConnectionDetails;
 import org.springframework.boot.autoconfigure.AutoConfigurations;
@@ -83,8 +85,6 @@ void allowsCustomConfigToBeUsed() {
 	void allowsPlatformThreadsToBeUsed() {
 		this.contextRunner.withUserConfiguration(BaseConfiguration.class).run((context) -> {
 			assertThat(context).hasSingleBean(OtlpMeterRegistry.class);
-			OtlpProperties properties = context.getBean(OtlpProperties.class);
-			assertThat(properties.isVirtualThreadsEnabled()).isFalse();
 			OtlpMeterRegistry registry = context.getBean(OtlpMeterRegistry.class);
 			assertThat(registry).extracting("scheduledExecutorService")
 				.satisfies((executor) -> ScheduledExecutorServiceAssert.assertThat((ScheduledExecutorService) executor)
@@ -93,13 +93,12 @@ void allowsPlatformThreadsToBeUsed() {
 	}
 
 	@Test
+	@EnabledForJreRange(min = JRE.JAVA_21)
 	void allowsVirtualThreadsToBeUsed() {
 		this.contextRunner.withUserConfiguration(BaseConfiguration.class)
-			.withPropertyValues("management.otlp.metrics.export.virtualThreadsEnabled=true")
+			.withPropertyValues("spring.threads.virtual.enabled=true")
 			.run((context) -> {
 				assertThat(context).hasSingleBean(OtlpMeterRegistry.class);
-				OtlpProperties properties = context.getBean(OtlpProperties.class);
-				assertThat(properties.isVirtualThreadsEnabled()).isTrue();
 				OtlpMeterRegistry registry = context.getBean(OtlpMeterRegistry.class);
 				assertThat(registry).extracting("scheduledExecutorService")
 					.satisfies(

spring-boot-project/spring-boot-actuator-autoconfigure/src/test/java/org/springframework/boot/actuate/autoconfigure/metrics/export/otlp/OtlpPropertiesTests.java

@@ -43,10 +43,4 @@ void defaultValuesAreConsistent() {
 		assertThat(properties.getBaseTimeUnit()).isSameAs(config.baseTimeUnit());
 	}
 
-	@Test
-	void virtualThreadsDisabledByDefault() {
-		OtlpProperties properties = new OtlpProperties();
-		assertThat(properties.isVirtualThreadsEnabled()).isFalse();
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-test-support/src/main/java/org/springframework/boot/testsupport/assertj/ScheduledExecutorServiceAssert.java

@@ -65,7 +65,14 @@ public ScheduledExecutorServiceAssert usesVirtualThreads() {
 
 	private boolean producesVirtualThreads() {
 		try {
-			return this.actual.schedule(() -> Thread.currentThread().isVirtual(), 0, TimeUnit.SECONDS).get();
+			return this.actual.schedule(() -> {
+				// https://openjdk.org/jeps/444
+				// jep 444 specifies that virtual threads will belong to
+				// a special thread group given the name "VirtualThreads"
+				ThreadGroup threadGroup = Thread.currentThread().getThreadGroup();
+				String threadGroupName = (threadGroup != null) ? threadGroup.getName() : "";
+				return threadGroupName.equalsIgnoreCase("VirtualThreads");
+			}, 0, TimeUnit.SECONDS).get();
 		}
 		catch (InterruptedException | ExecutionException ex) {
 			throw new AssertionError(ex);