--- a/nashorn/src/jdk/nashorn/internal/runtime/PropertyListenerManager.java	Wed Jun 12 11:22:06 2013 -0300
+++ b/nashorn/src/jdk/nashorn/internal/runtime/PropertyListenerManager.java	Wed Jun 12 16:41:38 2013 +0200
@@ -61,7 +61,7 @@
      *
      * @param listener The property listener that is added.
      */
-    public final void addPropertyListener(final PropertyListener listener) {
+    public synchronized final void addPropertyListener(final PropertyListener listener) {
         if (listeners == null) {
             listeners = new WeakHashMap<>();
         }
@@ -77,7 +77,7 @@
      *
      * @param listener The property listener that is removed.
      */
-    public final void removePropertyListener(final PropertyListener listener) {
+    public synchronized final void removePropertyListener(final PropertyListener listener) {
         if (listeners != null) {
             if (Context.DEBUG) {
                 listenersRemoved++;
@@ -92,7 +92,7 @@
      * @param object The ScriptObject to which property was added.
      * @param prop The property being added.
      */
-    protected final void notifyPropertyAdded(final ScriptObject object, final Property prop) {
+    protected synchronized final void notifyPropertyAdded(final ScriptObject object, final Property prop) {
         if (listeners != null) {
             for (PropertyListener listener : listeners.keySet()) {
                 listener.propertyAdded(object, prop);
@@ -106,7 +106,7 @@
      * @param object The ScriptObject from which property was deleted.
      * @param prop The property being deleted.
      */
-    protected final void notifyPropertyDeleted(final ScriptObject object, final Property prop) {
+    protected synchronized final void notifyPropertyDeleted(final ScriptObject object, final Property prop) {
         if (listeners != null) {
             for (PropertyListener listener : listeners.keySet()) {
                 listener.propertyDeleted(object, prop);
@@ -121,7 +121,7 @@
      * @param oldProp The old property being replaced.
      * @param newProp The new property that replaces the old property.
      */
-    protected final void notifyPropertyModified(final ScriptObject object, final Property oldProp, final Property newProp) {
+    protected synchronized final void notifyPropertyModified(final ScriptObject object, final Property oldProp, final Property newProp) {
         if (listeners != null) {
             for (PropertyListener listener : listeners.keySet()) {
                 listener.propertyModified(object, oldProp, newProp);

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8011893.js	Wed Jun 12 16:41:38 2013 +0200
@@ -0,0 +1,51 @@
+/*
+ * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
+ * 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.
+ */
+
+/**
+ * JDK-8011893: JS Object builtin prototype is not thread safe
+ *
+ * @test
+ * @run
+ */
+
+var a = {};
+var thread = new java.lang.Thread(new java.lang.Runnable() {
+    run: function() {
+        print("Thread starts");
+        for (var i = 0; i < 1000000; i++) {
+            // Unsubscribe to builtin, subscribe to new proto
+            var b = Object.create(a);
+        }
+        print("Thread done");
+    }
+});
+
+print("Main starts");
+thread.start();
+for (var j = 0; j < 1000000; j++) {
+    // Subscribe to builtin prototype.
+    a = {};
+}
+
+thread.join();
+print("Main done");

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nashorn/test/script/basic/JDK-8011893.js.EXPECTED	Wed Jun 12 16:41:38 2013 +0200
@@ -0,0 +1,4 @@
+Main starts
+Thread starts
+Thread done
+Main done