Merge branch '3.1.x'

Closes gh-37402

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplication.java

@@ -296,6 +296,9 @@ public class SpringApplication {
 	 * @return a running {@link ApplicationContext}
 	 */
 	public ConfigurableApplicationContext run(String... args) {
+		if (this.registerShutdownHook) {
+			SpringApplication.shutdownHook.enableShutdowHookAddition();
+		}
 		long startTime = System.nanoTime();
 		DefaultBootstrapContext bootstrapContext = createBootstrapContext();
 		ConfigurableApplicationContext context = null;

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationShutdownHook.java

@@ -62,12 +62,18 @@ class SpringApplicationShutdownHook implements Runnable {
 
 	private final AtomicBoolean shutdownHookAdded = new AtomicBoolean();
 
+	private volatile boolean shutdownHookAdditionEnabled = false;
+
 	private boolean inProgress;
 
 	SpringApplicationShutdownHandlers getHandlers() {
 		return this.handlers;
 	}
 
+	void enableShutdowHookAddition() {
+		this.shutdownHookAdditionEnabled = true;
+	}
+
 	void registerApplicationContext(ConfigurableApplicationContext context) {
 		addRuntimeShutdownHookIfNecessary();
 		synchronized (SpringApplicationShutdownHook.class) {
@@ -78,7 +84,7 @@ class SpringApplicationShutdownHook implements Runnable {
 	}
 
 	private void addRuntimeShutdownHookIfNecessary() {
-		if (this.shutdownHookAdded.compareAndSet(false, true)) {
+		if (this.shutdownHookAdditionEnabled && this.shutdownHookAdded.compareAndSet(false, true)) {
 			addRuntimeShutdownHook();
 		}
 	}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java

@@ -51,6 +51,7 @@ class SpringApplicationShutdownHookTests {
 	@Test
 	void shutdownHookIsNotAddedUntilContextIsRegistered() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
+		shutdownHook.enableShutdowHookAddition();
 		assertThat(shutdownHook.isRuntimeShutdownHookAdded()).isFalse();
 		ConfigurableApplicationContext context = new GenericApplicationContext();
 		shutdownHook.registerApplicationContext(context);
@@ -60,12 +61,25 @@ class SpringApplicationShutdownHookTests {
 	@Test
 	void shutdownHookIsNotAddedUntilHandlerIsRegistered() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
+		shutdownHook.enableShutdowHookAddition();
 		assertThat(shutdownHook.isRuntimeShutdownHookAdded()).isFalse();
 		shutdownHook.getHandlers().add(() -> {
 		});
 		assertThat(shutdownHook.isRuntimeShutdownHookAdded()).isTrue();
 	}
 
+	@Test
+	void shutdownHookIsNotAddedUntilAdditionIsEnabled() {
+		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
+		shutdownHook.getHandlers().add(() -> {
+		});
+		assertThat(shutdownHook.isRuntimeShutdownHookAdded()).isFalse();
+		shutdownHook.enableShutdowHookAddition();
+		shutdownHook.getHandlers().add(() -> {
+		});
+		assertThat(shutdownHook.isRuntimeShutdownHookAdded()).isTrue();
+	}
+
 	@Test
 	void runClosesContextsBeforeRunningHandlerActions() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();