--- old/src/java.base/share/classes/java/lang/ref/ReferenceQueue.java	2015-05-12 23:11:45.180647480 +0200
+++ new/src/java.base/share/classes/java/lang/ref/ReferenceQueue.java	2015-05-12 23:11:45.106648786 +0200
@@ -25,6 +25,8 @@
 
 package java.lang.ref;
 
+import java.util.function.Consumer;
+
 /**
  * Reference queues, to which registered reference objects are appended by the
  * garbage collector after the appropriate reachability changes are detected.
@@ -83,7 +85,7 @@
                 null :
                 r.next; // Unchecked due to the next field having a raw type in Reference
             r.queue = NULL;
-            r.next = r;
+            r.next = Reference.DEQUEUED;
             queueLength--;
             if (r instanceof FinalReference) {
                 sun.misc.VM.addFinalRefCount(-1);
@@ -164,4 +166,23 @@
         return remove(0);
     }
 
+    /**
+     * Iterate queue and invoke given action with each Reference.
+     * Suitable for diagnostic purposes.
+     */
+    void forEach(Consumer<? super Reference<? extends T>> action) {
+        for (Reference<? extends T> r = head; r != null;) {
+            action.accept(r);
+            Reference rn = r.next;
+            if (rn == r) {
+                // end of chain
+                r = null;
+            } else if (rn == Reference.DEQUEUED) {
+                // restart from head if overtaken by queue poller(s)
+                r = head;
+            } else {
+                r = rn;
+            }
+        }
+    }
 }