Wait for lenient bean creation in locked thread when necessary

Closes spring-projectsgh-34349

Author: jhoeller

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

@@ -24,6 +24,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.Condition;
 import java.util.concurrent.locks.Lock;
 import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
@@ -100,6 +101,15 @@ public class DefaultSingletonBeanRegistry extends SimpleAliasRegistry implements
 	/** Names of beans currently excluded from in creation checks. */
 	private final Set<String> inCreationCheckExclusions = ConcurrentHashMap.newKeySet(16);
 
+	/** Specific lock for lenient creation tracking. */
+	private final Lock lenientCreationLock = new ReentrantLock();
+
+	/** Specific lock condition for lenient creation tracking. */
+	private final Condition lenientCreationFinished = this.lenientCreationLock.newCondition();
+
+	/** Names of beans that are currently in lenient creation. */
+	private final Set<String> singletonsInLenientCreation = new HashSet<>();
+
 	/** Flag that indicates whether we're currently within destroySingletons. */
 	private volatile boolean singletonsCurrentlyInDestruction = false;
 
@@ -243,6 +253,7 @@ 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) {
@@ -257,6 +268,14 @@ 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);
+						}
+						finally {
+							this.lenientCreationLock.unlock();
+						}
 					}
 					else {
 						// No specific locking indication (outside a coordinated bootstrap) and
@@ -285,7 +304,24 @@ public Object getSingleton(String beanName, ObjectFactory<?> singletonFactory) {
 				}
 				catch (BeanCurrentlyInCreationException ex) {
 					if (locked) {
-						throw ex;
+						this.lenientCreationLock.lock();
+						try {
+							while ((singletonObject = this.singletonObjects.get(beanName)) == null) {
+								if (!this.singletonsInLenientCreation.contains(beanName)) {
+									throw ex;
+								}
+								try {
+									this.lenientCreationFinished.await();
+								}
+								catch (InterruptedException ie) {
+									Thread.currentThread().interrupt();
+								}
+							}
+							return singletonObject;
+						}
+						finally {
+							this.lenientCreationLock.unlock();
+						}
 					}
 					// Try late locking for waiting on specific bean to be finished.
 					this.singletonLock.lock();
@@ -339,6 +375,16 @@ 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();
+				}
+			}
 		}
 	}
 

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

@@ -19,14 +19,12 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.Timeout;
 
-import org.springframework.beans.factory.BeanCurrentlyInCreationException;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.testfixture.beans.TestBean;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.testfixture.EnabledForTestGroups;
 import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
 
-import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
 import static org.springframework.context.annotation.Bean.Bootstrap.BACKGROUND;
 import static org.springframework.core.testfixture.TestGroup.LONG_RUNNING;
 
@@ -42,8 +40,19 @@ class BackgroundBootstrapTests {
 	void bootstrapWithUnmanagedThread() {
 		ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(UnmanagedThreadBeanConfig.class);
 		ctx.getBean("testBean1", TestBean.class);
-		assertThatExceptionOfType(BeanCurrentlyInCreationException.class).isThrownBy(  // late - not during refresh
-				() -> ctx.getBean("testBean2", TestBean.class));
+		ctx.getBean("testBean2", TestBean.class);
+		ctx.close();
+	}
+
+	@Test
+	@Timeout(5)
+	@EnabledForTestGroups(LONG_RUNNING)
+	void bootstrapWithUnmanagedThreads() {
+		ConfigurableApplicationContext ctx = new AnnotationConfigApplicationContext(UnmanagedThreadsBeanConfig.class);
+		ctx.getBean("testBean1", TestBean.class);
+		ctx.getBean("testBean2", TestBean.class);
+		ctx.getBean("testBean3", TestBean.class);
+		ctx.getBean("testBean4", TestBean.class);
 		ctx.close();
 	}
 
@@ -55,6 +64,7 @@ void bootstrapWithCustomExecutor() {
 		ctx.getBean("testBean1", TestBean.class);
 		ctx.getBean("testBean2", TestBean.class);
 		ctx.getBean("testBean3", TestBean.class);
+		ctx.getBean("testBean4", TestBean.class);
 		ctx.close();
 	}
 
@@ -87,6 +97,45 @@ public TestBean testBean2() {
 	}
 
 
+	@Configuration(proxyBeanMethods = false)
+	static class UnmanagedThreadsBeanConfig {
+
+		@Bean
+		public TestBean testBean1(ObjectProvider<TestBean> testBean3, ObjectProvider<TestBean> testBean4) {
+			new Thread(testBean3::getObject).start();
+			new Thread(testBean4::getObject).start();
+			try {
+				Thread.sleep(1000);
+			}
+			catch (InterruptedException ex) {
+				throw new RuntimeException(ex);
+			}
+			return new TestBean();
+		}
+
+		@Bean
+		public TestBean testBean2(TestBean testBean4) {
+			return new TestBean(testBean4);
+		}
+
+		@Bean
+		public TestBean testBean3(TestBean testBean4) {
+			return new TestBean(testBean4);
+		}
+
+		@Bean
+		public TestBean testBean4() {
+			try {
+				Thread.sleep(2000);
+			}
+			catch (InterruptedException ex) {
+				throw new RuntimeException(ex);
+			}
+			return new TestBean();
+		}
+	}
+
+
 	@Configuration(proxyBeanMethods = false)
 	static class CustomExecutorBeanConfig {
 
@@ -117,8 +166,8 @@ public TestBean testBean3() {
 		}
 
 		@Bean
-		public String dependent(@Lazy TestBean testBean1, @Lazy TestBean testBean2, @Lazy TestBean testBean3) {
-			return "";
+		public TestBean testBean4(@Lazy TestBean testBean1, @Lazy TestBean testBean2, @Lazy TestBean testBean3) {
+			return new TestBean();
 		}
 	}