From 495665aec0cd5cbf27d1c0fdb3563669312122c2 Mon Sep 17 00:00:00 2001
From: Phillip Webb <phil.webb@broadcom.com>
Date: Tue, 17 Dec 2024 09:49:57 -0800
Subject: [PATCH] Use reverse order for shutdown hooks

Refine `SpringApplicationShutdownHook` so that shutdown happens in
reverse order to registration.

See gh-43430
---
 .../boot/SpringApplicationShutdownHook.java                | 7 +++++--
 .../boot/SpringApplicationShutdownHookTests.java           | 6 +++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationShutdownHook.java b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationShutdownHook.java
index 8e5e4ad3a34..433087a1bed 100644
--- a/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationShutdownHook.java
+++ b/spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationShutdownHook.java
@@ -16,8 +16,10 @@
 
 package org.springframework.boot;
 
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.LinkedHashSet;
+import java.util.List;
 import java.util.Set;
 import java.util.WeakHashMap;
 import java.util.concurrent.TimeUnit;
@@ -103,12 +105,13 @@ class SpringApplicationShutdownHook implements Runnable {
 	public void run() {
 		Set<ConfigurableApplicationContext> contexts;
 		Set<ConfigurableApplicationContext> closedContexts;
-		Set<Handler> handlers;
+		List<Handler> handlers;
 		synchronized (SpringApplicationShutdownHook.class) {
 			this.inProgress = true;
 			contexts = new LinkedHashSet<>(this.contexts);
 			closedContexts = new LinkedHashSet<>(this.closedContexts);
-			handlers = new LinkedHashSet<>(this.handlers.getActions());
+			handlers = new ArrayList<>(this.handlers.getActions());
+			Collections.reverse(handlers);
 		}
 		contexts.forEach(this::closeAndWait);
 		closedContexts.forEach(this::closeAndWait);
diff --git a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java
index 4d4d56947d7..b1854e25319 100644
--- a/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java
+++ b/spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java
@@ -207,7 +207,7 @@ class SpringApplicationShutdownHookTests {
 	}
 
 	@Test
-	void handlersRunInDeterministicOrder() {
+	void handlersRunInDeterministicOrderFromLastRegisteredToFirst() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
 		Runnable r1 = mock(Runnable.class);
 		Runnable r2 = mock(Runnable.class);
@@ -217,9 +217,9 @@ class SpringApplicationShutdownHookTests {
 		shutdownHook.getHandlers().add(r3);
 		shutdownHook.run();
 		InOrder ordered = inOrder(r1, r2, r3);
-		ordered.verify(r2).run();
-		ordered.verify(r1).run();
 		ordered.verify(r3).run();
+		ordered.verify(r1).run();
+		ordered.verify(r2).run();
 		ordered.verifyNoMoreInteractions();
 	}