From 46ec9916df0c8de14b43773f9da697040117886e Mon Sep 17 00:00:00 2001
From: melloware <mellowaredev@gmail.com>
Date: Sat, 20 Jun 2026 11:10:50 -0400
Subject: [PATCH 1/2] MYFACES-4757: 5.0 Fix race conditions of CopyOnWriteList

---
 .../application/ApplicationImplEventManager.java   | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java b/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
index 079831b9e..c860aa330 100644
--- a/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
+++ b/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
@@ -122,11 +122,11 @@ public void subscribeToEvent(Class<? extends SystemEvent> systemEventClass, Clas
         Assert.notNull(systemEventClass, "systemEventClass");
         Assert.notNull(listener, "listener");
 
-        List<EventInfo> eventInfos = globalListeners.get(systemEventClass);
+        // MYFACES-4757 use computeIfAbsent to prevent multiple threads from creating different lists
+        List eventInfos = globalListeners.get(systemEventClass);
         if (eventInfos == null)
         {
-            eventInfos = new CopyOnWriteArrayList<>();
-            globalListeners.put(systemEventClass, eventInfos);
+            eventInfos = globalListeners.computeIfAbsent(systemEventClass, k -> new CopyOnWriteArrayList<>());
         }
 
         EventInfo eventInfo = new EventInfo();
@@ -239,9 +239,9 @@ protected SystemEvent processComponentAttachedListeners(FacesContext facesContex
             return event;
         }
 
-        for (int i  = 0, size = listeners.size(); i < size; i++)
+        // MYFACES-4757: Use for each to prevent race condition
+        for (SystemEventListener listener : listeners)
         {
-            SystemEventListener listener = listeners.get(i);
             if (listener.isListenerForSource(source))
             {
                 // Lazy construct the event; zhis same event instance must be passed to all listener instances.
@@ -353,9 +353,9 @@ protected SystemEvent processGlobalListeners(FacesContext facesContext, List<Eve
             return event;
         }
         
-        for (int i  = 0, size = eventInfos.size(); i < size; i++)
+        // MYFACES-4757: Use for each to prevent race condition
+        for (EventInfo eventInfo : eventInfos)
         {
-            EventInfo eventInfo = eventInfos.get(i);
             if (eventInfo.sourceClass != null && !eventInfo.sourceClass.isAssignableFrom(sourceBaseType))
             {
                 continue;

From c42c6e97c4e0c387e1fd5f8932b8a2f8e3fb38ba Mon Sep 17 00:00:00 2001
From: melloware <mellowaredev@gmail.com>
Date: Sun, 21 Jun 2026 07:35:39 -0400
Subject: [PATCH 2/2] MYFACES-4757: 5.0 Fix race conditions of CopyOnWriteList

---
 .../apache/myfaces/application/ApplicationImplEventManager.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java b/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
index c860aa330..67bcdc644 100644
--- a/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
+++ b/impl/src/main/java/org/apache/myfaces/application/ApplicationImplEventManager.java
@@ -123,7 +123,7 @@ public void subscribeToEvent(Class<? extends SystemEvent> systemEventClass, Clas
         Assert.notNull(listener, "listener");
 
         // MYFACES-4757 use computeIfAbsent to prevent multiple threads from creating different lists
-        List eventInfos = globalListeners.get(systemEventClass);
+        List<EventInfo> eventInfos = globalListeners.get(systemEventClass);
         if (eventInfos == null)
         {
             eventInfos = globalListeners.computeIfAbsent(systemEventClass, k -> new CopyOnWriteArrayList<>());