Fix #4930: 2.3 IterationManager double checked lock idiom

Signed-off-by: melloware <mellowaredev@gmail.com>
eclipse-ee4j · Nov 6, 2021 · 99b0dd3 · 99b0dd3
1 parent 8d73d7c
commit 99b0dd3
Showing 1 changed file with 6 additions and 1 deletion.
diff --git a/impl/src/main/java/com/sun/faces/facelets/tag/jsf/IterationIdManager.java b/impl/src/main/java/com/sun/faces/facelets/tag/jsf/IterationIdManager.java
@@ -82,7 +82,12 @@ static boolean isIterating(FaceletContext context){
     private static Deque<Set<String>> _getStackOfTrackedIds(FaceletContext ctx) {
         Deque<Set<String>> stack = (Deque<Set<String>>)ctx.getAttribute(_STACK_OF_TRACKED_IDS);
         if (stack == null) {
-            stack = new LinkedList<>();
+            synchronized(IterationIdManager.class) {
+                if(stack == null) {
+                   stack = new LinkedList<>();
+                }
+            }
+
             ctx.setAttribute(_STACK_OF_TRACKED_IDS, stack);
         }
         return stack;