Notify lenientCreationFinished condition after locked creation as well

Closes gh-34522

Author: jhoeller

Diff for: spring-beans/src/main/java/org/springframework/beans/factory/support/DefaultSingletonBeanRegistry.java

@@ -253,7 +253,6 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 		Boolean lockFlag = isCurrentThreadAllowedToHoldSingletonLock();
 		boolean acquireLock = !Boolean.FALSE.equals(lockFlag);
 		boolean locked = (acquireLock && this.singletonLock.tryLock());
-		boolean lenient = false;
 		try {
 			Object singletonObject = this.singletonObjects.get(beanName);
 			if (singletonObject == null) {
@@ -268,7 +267,6 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 									Thread.currentThread().getName() + "\" while other thread holds " +
 									"singleton lock for other beans " + this.singletonsCurrentlyInCreation);
 						}
-						lenient = true;
 						this.lenientCreationLock.lock();
 						try {
 							this.singletonsInLenientCreation.add(beanName);
@@ -329,7 +327,7 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 					// Try late locking for waiting on specific bean to be finished.
 					this.singletonLock.lock();
 					locked = true;
-					// Singleton object should have appeared in the meantime.
+					// Lock-created singleton object should have appeared in the meantime.
 					singletonObject = this.singletonObjects.get(beanName);
 					if (singletonObject != null) {
 						return singletonObject;
@@ -343,8 +341,12 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 					this.suppressedExceptions = new LinkedHashSet<>();
 				}
 				try {
-					singletonObject = singletonFactory.getObject();
-					newSingleton = true;
+					// Leniently created singleton object could have appeared in the meantime.
+					singletonObject = this.singletonObjects.get(beanName);
+					if (singletonObject == null) {
+						singletonObject = singletonFactory.getObject();
+						newSingleton = true;
+					}
 				}
 				catch (IllegalStateException ex) {
 					// Has the singleton object implicitly appeared in the meantime ->
@@ -388,15 +390,13 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 			if (locked) {
 				this.singletonLock.unlock();
 			}
-			if (lenient) {
-				this.lenientCreationLock.lock();
-				try {
-					this.singletonsInLenientCreation.remove(beanName);
-					this.lenientCreationFinished.signalAll();
-				}
-				finally {
-					this.lenientCreationLock.unlock();
-				}
+			this.lenientCreationLock.lock();
+			try {
+				this.singletonsInLenientCreation.remove(beanName);
+				this.lenientCreationFinished.signalAll();
+			}
+			finally {
+				this.lenientCreationLock.unlock();
 			}
 		}
 	}

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

@@ -56,6 +56,16 @@ void bootstrapWithUnmanagedThreads() {
 		ctx.close();
 	}
 
+	@Test
+	@Timeout(5)
+	@EnabledForTestGroups(LONG_RUNNING)
+	void bootstrapWithCircularReference() {
+		ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(CircularReferenceBeanConfig.class);
+		ctx.getBean("testBean1", TestBean.class);
+		ctx.getBean("testBean2", TestBean.class);
+		ctx.close();
+	}
+
 	@Test
 	@Timeout(5)
 	@EnabledForTestGroups(LONG_RUNNING)
@@ -138,6 +148,34 @@ public TestBean testBean4() {
 	}
 
 
+	@Configuration(proxyBeanMethods = false)
+	static class CircularReferenceBeanConfig {
+
+		@Bean
+		public TestBean testBean1(ObjectProvider<TestBean> testBean2) {
+			new Thread(testBean2::getObject).start();
+			try {
+				Thread.sleep(1000);
+			}
+			catch (InterruptedException ex) {
+				throw new RuntimeException(ex);
+			}
+			return new TestBean();
+		}
+
+		@Bean
+		public TestBean testBean2(TestBean testBean1) {
+			try {
+				Thread.sleep(2000);
+			}
+			catch (InterruptedException ex) {
+				throw new RuntimeException(ex);
+			}
+			return new TestBean();
+		}
+	}
+
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomExecutorBeanConfig {