*) adding synchronization block because SimpleDateFormat is not thread-safe

See: http://www.yacy-forum.de/viewtopic.php?p=26906#26906

git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@2809 6c8d7289-2bf4-0310-a012-ef5d649a1542

source/de/anomic/http/httpc.java

@@ -545,7 +545,15 @@ public final class httpc {
     */
     public static String dateString(Date date) {
         if (date == null) return "";
-        return HTTPGMTFormatter.format(date);
+        
+        /*
+         * This synchronized is needed because SimpleDateFormat
+         * is not thread-safe.
+         * See: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6231579
+         */
+        synchronized(HTTPGMTFormatter) {
+        	return HTTPGMTFormatter.format(date);
+        }
     }
 
     /**