--- a/jdk/src/share/classes/sun/awt/AppContext.java	Wed Oct 09 15:34:53 2013 +0400
+++ b/jdk/src/share/classes/sun/awt/AppContext.java	Wed Oct 09 20:59:08 2013 +0400
@@ -167,6 +167,9 @@
      */
     private static volatile AppContext mainAppContext = null;
 
+    private static class GetAppContextLock {};
+    private final static Object getAppContextLock = new GetAppContextLock();
+
     /*
      * The hash map associated with this AppContext.  A private delegate
      * is used instead of subclassing HashMap so as to avoid all of
@@ -309,14 +312,16 @@
                     // if no contexts have been created yet. This covers standalone apps
                     // and excludes applets because by the time applet starts
                     // a number of contexts have already been created by the plugin.
-                    if (numAppContexts.get() == 0) {
-                        if (System.getProperty("javaplugin.version") == null &&
-                                System.getProperty("javawebstart.version") == null) {
-                            initMainAppContext();
-                        } else if (System.getProperty("javafx.version") != null &&
-                                threadGroup.getParent() != null) {
-                            // Swing inside JavaFX case
-                            SunToolkit.createNewAppContext();
+                    synchronized (getAppContextLock) {
+                        if (numAppContexts.get() == 0) {
+                            if (System.getProperty("javaplugin.version") == null &&
+                                    System.getProperty("javawebstart.version") == null) {
+                                initMainAppContext();
+                            } else if (System.getProperty("javafx.version") != null &&
+                                    threadGroup.getParent() != null) {
+                                // Swing inside JavaFX case
+                                SunToolkit.createNewAppContext();
+                            }
                         }
                     }