8150780: Repeated offer and remove on ConcurrentLinkedQueue lead to an OutOfMemoryError

Reviewed-by: martin, rasbold

src/share/classes/java/util/concurrent/ConcurrentLinkedQueue.java

@@ -485,19 +485,25 @@ public class ConcurrentLinkedQueue<E> extends AbstractQueue<E>
      * @return {@code true} if this queue changed as a result of the call
      */
     public boolean remove(Object o) {
-        if (o == null) return false;
-        Node<E> pred = null;
-        for (Node<E> p = first(); p != null; p = succ(p)) {
-            E item = p.item;
-            if (item != null &&
-                o.equals(item) &&
-                p.casItem(item, null)) {
-                Node<E> next = succ(p);
-                if (pred != null && next != null)
+        if (o != null) {
+            Node<E> next, pred = null;
+            for (Node<E> p = first(); p != null; pred = p, p = next) {
+                boolean removed = false;
+                E item = p.item;
+                if (item != null) {
+                    if (!o.equals(item)) {
+                        next = succ(p);
+                        continue;
+                    }
+                    removed = p.casItem(item, null);
+                }
+
+                next = succ(p);
+                if (pred != null && next != null) // unlink
                     pred.casNext(p, next);
-                return true;
+                if (removed)
+                    return true;
             }
-            pred = p;
         }
         return false;
     }

test/java/util/concurrent/ConcurrentLinkedQueue/RemoveLeak.java

+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * This file is available under and governed by the GNU General Public
+ * License version 2 only, as published by the Free Software Foundation.
+ * However, the following notice accompanied the original version of this
+ * file:
+ *
+ * Written by Martin Buchholz with assistance from members of JCP
+ * JSR-166 Expert Group and released to the public domain, as
+ * explained at http://creativecommons.org/publicdomain/zero/1.0/
+ */
+
+/*
+ * @test
+ * @bug 8054446 8137184 8137185
+ * @summary Regression test for memory leak in remove(Object)
+ * @run main/othervm -Xmx2200k RemoveLeak
+ */
+
+import java.util.concurrent.ConcurrentLinkedQueue;
+
+public class RemoveLeak {
+    public static void main(String[] args) {
+        int i = 0;
+        // Without bug fix, OutOfMemoryError was observed at iteration 65120
+        int iterations = 10 * 65120;
+        try {
+            ConcurrentLinkedQueue<Long> queue = new ConcurrentLinkedQueue<>();
+            queue.add(0L);
+            while (i++ < iterations) {
+                queue.add(1L);
+                queue.remove(1L);
+            }
+        } catch (Error t) {
+            System.err.printf("failed at iteration %d/%d%n", i, iterations);
+            throw t;
+        }
+    }
+}