Mark bootstrap thread for entire finishBeanFactoryInitialization phase

Closes gh-35398

spring-beans/src/main/java/org/springframework/beans/factory/config/ConfigurableListableBeanFactory.java

@@ -152,6 +152,18 @@ public interface ConfigurableListableBeanFactory
 	 */
 	boolean isConfigurationFrozen();
 
+	/**
+	 * Mark current thread as main bootstrap thread for singleton instantiation,
+	 * with lenient bootstrap locking applying for background threads.
+	 * <p>Any such marker is to be removed at the end of the managed bootstrap in
+	 * {@link #preInstantiateSingletons()}.
+	 * @since 6.2.12
+	 * @see #setBootstrapExecutor
+	 * @see #preInstantiateSingletons()
+	 */
+	default void prepareSingletonBootstrap() {
+	}
+
 	/**
 	 * Ensure that all non-lazy-init singletons are instantiated, also considering
 	 * {@link org.springframework.beans.factory.FactoryBean FactoryBeans}.
@@ -159,6 +171,7 @@ public interface ConfigurableListableBeanFactory
 	 * @throws BeansException if one of the singleton beans could not be created.
 	 * Note: This may have left the factory with some beans already initialized!
 	 * Call {@link #destroySingletons()} for full cleanup in this case.
+	 * @see #prepareSingletonBootstrap()
 	 * @see #destroySingletons()
 	 */
 	void preInstantiateSingletons() throws BeansException;

spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultListableBeanFactory.java

@@ -1102,6 +1102,11 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 		return null;
 	}
 
+	@Override
+	public void prepareSingletonBootstrap() {
+		this.mainThreadPrefix = getThreadNamePrefix();
+	}
+
 	@Override
 	public void preInstantiateSingletons() throws BeansException {
 		if (logger.isTraceEnabled()) {
@@ -1114,7 +1119,9 @@ public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFacto
 
 		// Trigger initialization of all non-lazy singleton beans...
 		this.preInstantiationThread.set(PreInstantiation.MAIN);
+		if (this.mainThreadPrefix == null) {
 			this.mainThreadPrefix = getThreadNamePrefix();
+		}
 		try {
 			List<CompletableFuture<?>> futures = new ArrayList<>();
 			for (String beanName : beanNames) {

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -936,6 +936,9 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 	 */
 	@SuppressWarnings("unchecked")
 	protected void finishBeanFactoryInitialization(ConfigurableListableBeanFactory beanFactory) {
+		// Mark current thread for singleton instantiation with applied bootstrap locking.
+		beanFactory.prepareSingletonBootstrap();
+
 		// Initialize bootstrap executor for this context.
 		if (beanFactory.containsBean(BOOTSTRAP_EXECUTOR_BEAN_NAME) &&
 				beanFactory.isTypeMatch(BOOTSTRAP_EXECUTOR_BEAN_NAME, Executor.class)) {

spring-context/src/test/java/org/springframework/context/annotation/BackgroundBootstrapTests.java

@@ -31,6 +31,7 @@ import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.context.weaving.LoadTimeWeaverAware;
 import org.springframework.core.SpringProperties;
 import org.springframework.core.testfixture.EnabledForTestGroups;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
@@ -68,6 +69,16 @@ class BackgroundBootstrapTests {
 		ctx.close();
 	}
 
+	@Test
+	@Timeout(10)
+	@EnabledForTestGroups(LONG_RUNNING)
+	void bootstrapWithLoadTimeWeaverAware() {
+		ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(LoadTimeWeaverAwareBeanConfig.class);
+		ctx.getBean("testBean1", TestBean.class);
+		ctx.getBean("testBean2", TestBean.class);
+		ctx.close();
+	}
+
 	@Test
 	@Timeout(10)
 	@EnabledForTestGroups(LONG_RUNNING)
@@ -266,6 +277,50 @@ class BackgroundBootstrapTests {
 	}
 
 
+	@Configuration(proxyBeanMethods = false)
+	static class LoadTimeWeaverAwareBeanConfig {
+
+		@Bean
+		LoadTimeWeaverAware loadTimeWeaverAware(ObjectProvider<TestBean> testBean1) {
+			Thread thread = new Thread(testBean1::getObject);
+			thread.start();
+			try {
+				thread.join();
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+			return (loadTimeWeaver -> {});
+		}
+
+		@Bean
+		public TestBean testBean1(TestBean testBean2) {
+			return new TestBean(testBean2);
+		}
+
+		@Bean @Lazy
+		public FactoryBean<TestBean> testBean2() {
+			try {
+				Thread.sleep(2000);
+			}
+			catch (InterruptedException ex) {
+				Thread.currentThread().interrupt();
+			}
+			TestBean testBean = new TestBean();
+			return new FactoryBean<>() {
+				@Override
+				public TestBean getObject() {
+					return testBean;
+				}
+				@Override
+				public Class<?> getObjectType() {
+					return testBean.getClass();
+				}
+			};
+		}
+	}
+
+
 	@Configuration(proxyBeanMethods = false)
 	static class StrictLockingBeanConfig {