Add virtual thread support

.github/actions/setup-test-jdk/action.yml

@@ -9,3 +9,9 @@ runs:
         java-version: 8
     - shell: bash
       run: echo "JDK8=$JAVA_HOME" >> $GITHUB_ENV
+    - uses: oracle-actions/setup-java@v1
+      with:
+        website: jdk.java.net
+        release: 21
+    - shell: bash
+      run: echo "JDK21=$JAVA_HOME" >> $GITHUB_ENV

gradle/config/checkstyle/suppressions.xml

@@ -4,4 +4,6 @@
 		files="junit-platform-commons[\\/]src[\\/]main[\\/]java.+?[\\/]org[\\/]junit[\\/]platform[\\/]commons[\\/]util[\\/]*"/>
 	<suppress checks="JavadocPackage"
 		files="junit-platform-console[\\/]src[\\/]main[\\/]java.+?[\\/]org[\\/]junit[\\/]platform[\\/]console[\\/]*"/>
+	<suppress checks="JavadocPackage"
+		files="junit-platform-engine[\\/]src[\\/]main[\\/]java.+[\\/]org[\\/]junit[\\/]platform[\\/]engine[\\/]support[\\/]hierarchical[\\/]*"/>
 </suppressions>

gradle/plugins/common/src/main/kotlin/junitbuild.java-library-conventions.gradle.kts

@@ -147,9 +147,8 @@ val allMainClasses by tasks.registering {
 
 val prepareModuleSourceDir by tasks.registering(Sync::class) {
     from(moduleSourceDir)
-    from(sourceSets.matching { it.name.startsWith("main") }.map { it.allJava })
+    from(sourceSets.main.map { it.allJava })
     into(combinedModuleSourceDir.map { it.dir(javaModuleName) })
-    duplicatesStrategy = DuplicatesStrategy.EXCLUDE
 }
 
 val compileModule by tasks.registering(JavaCompile::class) {

gradle/plugins/common/src/main/kotlin/junitbuild.java-multi-release-sources.gradle.kts

@@ -6,7 +6,7 @@ plugins {
 
 val mavenizedProjects: List<Project> by rootProject.extra
 
-listOf(9, 17).forEach { javaVersion ->
+listOf(9, 17, 21).forEach { javaVersion ->
 	val sourceSet = sourceSets.register("mainRelease${javaVersion}") {
 		compileClasspath += sourceSets.main.get().output
 		runtimeClasspath += sourceSets.main.get().output
@@ -27,6 +27,11 @@ listOf(9, 17).forEach { javaVersion ->
 
 		named<JavaCompile>(sourceSet.get().compileJavaTaskName).configure {
 			options.release = javaVersion
+			if (javaVersion == 21) {
+                javaCompiler.set(javaToolchains.compilerFor {
+                    languageVersion.set(JavaLanguageVersion.of(javaVersion))
+                })
+            }
 		}
 
 		named<Checkstyle>("checkstyle${sourceSet.name.capitalized()}").configure {

gradle/plugins/common/src/main/kotlin/junitbuild/exec/RunConsoleLauncher.kt

@@ -25,6 +25,9 @@ abstract class RunConsoleLauncher @Inject constructor(private val execOperations
     @get:Classpath
     abstract val runtimeClasspath: ConfigurableFileCollection
 
+    @get:Input
+    abstract val jvmArgs: ListProperty<String>
+
     @get:Input
     abstract val args: ListProperty<String>
 
@@ -62,6 +65,7 @@ abstract class RunConsoleLauncher @Inject constructor(private val execOperations
         val output = ByteArrayOutputStream()
         val result = execOperations.javaexec {
             executable = javaLauncher.get().executablePath.asFile.absolutePath
+            jvmArgs(this@RunConsoleLauncher.jvmArgs.get())
             classpath = runtimeClasspath
             mainClass.set("org.junit.platform.console.ConsoleLauncher")
             args(this@RunConsoleLauncher.args.get())
@@ -82,6 +86,12 @@ abstract class RunConsoleLauncher @Inject constructor(private val execOperations
         result.rethrowFailure().assertNormalExitValue()
     }
 
+    @Suppress("unused")
+    @Option(option = "jvm-args", description = "JVM args for the console launcher")
+    fun setVMArgs(args: String) {
+        jvmArgs.set(Commandline.translateCommandline(args).toList())
+    }
+
     @Suppress("unused")
     @Option(option = "args", description = "Additional command line arguments for the console launcher")
     fun setCliArgs(args: String) {

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/Constants.java

@@ -124,6 +124,8 @@ public final class Constants {
 	@API(status = STABLE, since = "5.10")
 	public static final String PARALLEL_EXECUTION_ENABLED_PROPERTY_NAME = JupiterConfiguration.PARALLEL_EXECUTION_ENABLED_PROPERTY_NAME;
 
+	public static final String PARALLEL_EXECUTOR_PROPERTY_NAME = JupiterConfiguration.PARALLEL_EXECUTOR_PROPERTY_NAME;
+
 	/**
 	 * Property name used to set the default test execution mode: {@value}
 	 *

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/JupiterTestEngine.java

@@ -11,6 +11,7 @@
 package org.junit.jupiter.engine;
 
 import static org.apiguardian.api.API.Status.INTERNAL;
+import static org.junit.jupiter.engine.config.JupiterConfiguration.ParallelExecutor.VIRTUAL;
 
 import java.util.Optional;
 
@@ -22,6 +23,7 @@
 import org.junit.jupiter.engine.discovery.DiscoverySelectorResolver;
 import org.junit.jupiter.engine.execution.JupiterEngineExecutionContext;
 import org.junit.jupiter.engine.support.JupiterThrowableCollectorFactory;
+import org.junit.platform.engine.ConfigurationParameters;
 import org.junit.platform.engine.EngineDiscoveryRequest;
 import org.junit.platform.engine.ExecutionRequest;
 import org.junit.platform.engine.TestDescriptor;
@@ -31,6 +33,7 @@
 import org.junit.platform.engine.support.hierarchical.HierarchicalTestEngine;
 import org.junit.platform.engine.support.hierarchical.HierarchicalTestExecutorService;
 import org.junit.platform.engine.support.hierarchical.ThrowableCollector;
+import org.junit.platform.engine.support.hierarchical.VirtualThreadHierarchicalTestExecutorServiceFactory;
 
 /**
  * The JUnit Jupiter {@link org.junit.platform.engine.TestEngine TestEngine}.
@@ -74,8 +77,12 @@ public TestDescriptor discover(EngineDiscoveryRequest discoveryRequest, UniqueId
 	protected HierarchicalTestExecutorService createExecutorService(ExecutionRequest request) {
 		JupiterConfiguration configuration = getJupiterConfiguration(request);
 		if (configuration.isParallelExecutionEnabled()) {
-			return new ForkJoinPoolHierarchicalTestExecutorService(new PrefixedConfigurationParameters(
-				request.getConfigurationParameters(), Constants.PARALLEL_CONFIG_PREFIX));
+			ConfigurationParameters configurationParameters = new PrefixedConfigurationParameters(
+				request.getConfigurationParameters(), Constants.PARALLEL_CONFIG_PREFIX);
+			if (configuration.getParallelExecutor() == VIRTUAL) {
+				return VirtualThreadHierarchicalTestExecutorServiceFactory.create(configurationParameters);
+			}
+			return new ForkJoinPoolHierarchicalTestExecutorService(configurationParameters);
 		}
 		return super.createExecutorService(request);
 	}

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/config/CachingJupiterConfiguration.java

@@ -67,6 +67,12 @@ public boolean isExtensionAutoDetectionEnabled() {
 			key -> delegate.isExtensionAutoDetectionEnabled());
 	}
 
+	@Override
+	public ParallelExecutor getParallelExecutor() {
+		return (ParallelExecutor) cache.computeIfAbsent(PARALLEL_EXECUTOR_PROPERTY_NAME,
+			key -> delegate.getParallelExecutor());
+	}
+
 	@Override
 	public ExecutionMode getDefaultExecutionMode() {
 		return (ExecutionMode) cache.computeIfAbsent(DEFAULT_EXECUTION_MODE_PROPERTY_NAME,

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/config/DefaultJupiterConfiguration.java

@@ -41,6 +41,9 @@
 @API(status = INTERNAL, since = "5.4")
 public class DefaultJupiterConfiguration implements JupiterConfiguration {
 
+	private static final EnumConfigurationParameterConverter<ParallelExecutor> parallelExecutorConverter = //
+		new EnumConfigurationParameterConverter<>(ParallelExecutor.class, "parallel executor");
+
 	private static final EnumConfigurationParameterConverter<ExecutionMode> executionModeConverter = //
 		new EnumConfigurationParameterConverter<>(ExecutionMode.class, "parallel execution mode");
 
@@ -89,6 +92,12 @@ public boolean isExtensionAutoDetectionEnabled() {
 		return configurationParameters.getBoolean(EXTENSIONS_AUTODETECTION_ENABLED_PROPERTY_NAME).orElse(false);
 	}
 
+	@Override
+	public ParallelExecutor getParallelExecutor() {
+		return parallelExecutorConverter.get(configurationParameters, PARALLEL_EXECUTOR_PROPERTY_NAME,
+			ParallelExecutor.FORK_JOIN_POOL);
+	}
+
 	@Override
 	public ExecutionMode getDefaultExecutionMode() {
 		return executionModeConverter.get(configurationParameters, DEFAULT_EXECUTION_MODE_PROPERTY_NAME,

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/config/JupiterConfiguration.java

@@ -36,6 +36,7 @@ public interface JupiterConfiguration {
 
 	String DEACTIVATE_CONDITIONS_PATTERN_PROPERTY_NAME = "junit.jupiter.conditions.deactivate";
 	String PARALLEL_EXECUTION_ENABLED_PROPERTY_NAME = "junit.jupiter.execution.parallel.enabled";
+	String PARALLEL_EXECUTOR_PROPERTY_NAME = "junit.jupiter.execution.parallel.executor";
 	String DEFAULT_EXECUTION_MODE_PROPERTY_NAME = Execution.DEFAULT_EXECUTION_MODE_PROPERTY_NAME;
 	String DEFAULT_CLASSES_EXECUTION_MODE_PROPERTY_NAME = Execution.DEFAULT_CLASSES_EXECUTION_MODE_PROPERTY_NAME;
 	String EXTENSIONS_AUTODETECTION_ENABLED_PROPERTY_NAME = "junit.jupiter.extensions.autodetection.enabled";
@@ -52,6 +53,8 @@ public interface JupiterConfiguration {
 
 	boolean isExtensionAutoDetectionEnabled();
 
+	ParallelExecutor getParallelExecutor();
+
 	ExecutionMode getDefaultExecutionMode();
 
 	ExecutionMode getDefaultClassesExecutionMode();
@@ -70,4 +73,7 @@ public interface JupiterConfiguration {
 
 	Supplier<TempDirFactory> getDefaultTempDirFactorySupplier();
 
+	enum ParallelExecutor {
+		FORK_JOIN_POOL, VIRTUAL
+	}
 }

junit-platform-engine/junit-platform-engine.gradle.kts

@@ -1,5 +1,6 @@
 plugins {
 	id("junitbuild.java-library-conventions")
+	id("junitbuild.java-multi-release-sources")
 	`java-test-fixtures`
 }
 
@@ -17,3 +18,28 @@ dependencies {
 	osgiVerification(projects.junitJupiterEngine)
 	osgiVerification(projects.junitPlatformLauncher)
 }
+
+tasks.jar {
+	val release21ClassesDir = project.sourceSets.mainRelease21.get().output.classesDirs.singleFile
+	inputs.dir(release21ClassesDir).withPathSensitivity(PathSensitivity.RELATIVE)
+	doLast(objects.newInstance(junitbuild.java.ExecJarAction::class).apply {
+		javaLauncher.set(project.javaToolchains.launcherFor {
+			languageVersion.set(java.toolchain.languageVersion.map {
+				if (it.canCompileOrRun(21)) it else JavaLanguageVersion.of(21)
+			})
+		})
+		args.addAll(
+			"--update",
+			"--file", archiveFile.get().asFile.absolutePath,
+			"--release", "21",
+			"-C", release21ClassesDir.absolutePath, "."
+		)
+	})
+}
+
+
+eclipse {
+	classpath {
+		sourceSets -= project.sourceSets.mainRelease21.get()
+	}
+}

junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/DefaultParallelExecutionConfigurationStrategy.java

@@ -216,7 +216,7 @@ public ParallelExecutionConfiguration createConfiguration(ConfigurationParameter
 	 */
 	public static final String CONFIG_CUSTOM_CLASS_PROPERTY_NAME = "custom.class";
 
-	static ParallelExecutionConfigurationStrategy getStrategy(ConfigurationParameters configurationParameters) {
+	public static ParallelExecutionConfigurationStrategy getStrategy(ConfigurationParameters configurationParameters) {
 		return valueOf(
 			configurationParameters.get(CONFIG_STRATEGY_PROPERTY_NAME).orElse("dynamic").toUpperCase(Locale.ROOT));
 	}

junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/ForkJoinPoolHierarchicalTestExecutorService.java

@@ -208,10 +208,13 @@ public void compute() {
 
 	}
 
-	static class WorkerThreadFactory implements ForkJoinPool.ForkJoinWorkerThreadFactory {
+	public static class WorkerThreadFactory implements ForkJoinPool.ForkJoinWorkerThreadFactory {
 
 		private final ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
 
+		public WorkerThreadFactory() {
+		}
+
 		@Override
 		public ForkJoinWorkerThread newThread(ForkJoinPool pool) {
 			return new WorkerThread(pool, contextClassLoader);

junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/VirtualThreadHierarchicalTestExecutorServiceFactory.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2015-2023 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.platform.engine.support.hierarchical;
+
+import org.junit.platform.engine.ConfigurationParameters;
+
+public class VirtualThreadHierarchicalTestExecutorServiceFactory {
+
+	public static HierarchicalTestExecutorService create(
+			@SuppressWarnings("unused") ConfigurationParameters configurationParameters) {
+		throw new IllegalArgumentException("The virtual executor is only supported on Java 21 and above");
+	}
+
+	private VirtualThreadHierarchicalTestExecutorServiceFactory() {
+		throw new AssertionError();
+	}
+}

junit-platform-engine/src/main/java21/org/junit/platform/engine/support/hierarchical/VirtualThreadHierarchicalTestExecutorService.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2015-2023 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.platform.engine.support.hierarchical;
+
+import static java.util.concurrent.CompletableFuture.completedFuture;
+import static java.util.function.Predicate.isEqual;
+import static java.util.stream.Collectors.toCollection;
+import static org.junit.platform.commons.util.FunctionUtils.where;
+import static org.junit.platform.engine.support.hierarchical.Node.ExecutionMode.CONCURRENT;
+import static org.junit.platform.engine.support.hierarchical.Node.ExecutionMode.SAME_THREAD;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ForkJoinPool;
+import java.util.concurrent.TimeUnit;
+import java.util.stream.Stream;
+
+import org.junit.platform.commons.util.ExceptionUtils;
+import org.junit.platform.engine.ConfigurationParameters;
+import org.junit.platform.engine.support.hierarchical.Node.ExecutionMode;
+
+class VirtualThreadHierarchicalTestExecutorService implements HierarchicalTestExecutorService {
+
+	private final ClassLoader contextClassLoader;
+	private final ForkJoinPool forkJoinPool;
+	private final ExecutorService executorService;
+
+	VirtualThreadHierarchicalTestExecutorService(ConfigurationParameters configurationParameters) {
+		contextClassLoader = Thread.currentThread().getContextClassLoader();
+		var strategy = DefaultParallelExecutionConfigurationStrategy.getStrategy(configurationParameters);
+		var configuration = strategy.createConfiguration(configurationParameters);
+		var systemThreadFactory = new ForkJoinPoolHierarchicalTestExecutorService.WorkerThreadFactory();
+		forkJoinPool = new ForkJoinPool(configuration.getParallelism(), systemThreadFactory, null, false,
+			configuration.getCorePoolSize(), configuration.getMaxPoolSize(), configuration.getMinimumRunnable(), null,
+			configuration.getKeepAliveSeconds(), TimeUnit.SECONDS);
+		var virtualThreadFactory = Thread.ofVirtual().name("junit-executor", 1).factory();
+		executorService = Executors.newThreadPerTaskExecutor(virtualThreadFactory);
+	}
+
+	@Override
+	public CompletableFuture<Void> submit(TestTask testTask) {
+		if (testTask.getExecutionMode() == CONCURRENT) {
+			return CompletableFuture.runAsync(() -> executeWithLocksAndContextClassLoader(testTask), executorService);
+		}
+		executeWithLocks(testTask);
+		return completedFuture(null);
+	}
+
+	private void executeWithLocksAndContextClassLoader(TestTask testTask) {
+		Thread.currentThread().setContextClassLoader(contextClassLoader);
+		executeWithLocks(testTask);
+	}
+
+	private void executeWithLocks(TestTask testTask) {
+		var lock = testTask.getResourceLock();
+		try {
+			lock.acquire();
+			testTask.execute();
+		}
+		catch (InterruptedException e) {
+			ExceptionUtils.throwAsUncheckedException(e);
+		}
+		finally {
+			lock.release();
+		}
+	}
+
+	@Override
+	public void invokeAll(List<? extends TestTask> testTasks) {
+		var futures = submitAll(testTasks, CONCURRENT).collect(toCollection(ArrayList::new));
+		submitAll(testTasks, SAME_THREAD).forEach(futures::add);
+		allOf(futures).join();
+	}
+
+	private Stream<CompletableFuture<Void>> submitAll(List<? extends TestTask> testTasks, ExecutionMode mode) {
+		return testTasks.stream().filter(where(TestTask::getExecutionMode, isEqual(mode))).map(this::submit);
+	}
+
+	private CompletableFuture<Void> allOf(List<CompletableFuture<Void>> futures) {
+		return CompletableFuture.allOf(futures.toArray(CompletableFuture[]::new));
+	}
+
+	@Override
+	public void close() {
+		executorService.close();
+		forkJoinPool.close();
+	}
+}

junit-platform-engine/src/main/java21/org/junit/platform/engine/support/hierarchical/VirtualThreadHierarchicalTestExecutorServiceFactory.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2015-2023 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.platform.engine.support.hierarchical;
+
+import org.junit.platform.engine.ConfigurationParameters;
+
+public class VirtualThreadHierarchicalTestExecutorServiceFactory {
+
+	public static HierarchicalTestExecutorService create(ConfigurationParameters configurationParameters) {
+		return new VirtualThreadHierarchicalTestExecutorService(configurationParameters);
+	}
+
+	private VirtualThreadHierarchicalTestExecutorServiceFactory() {
+		throw new AssertionError();
+	}
+}