--- a/src/share/classes/javax/management/timer/Timer.java	Wed May 11 08:54:16 2011 -0700
+++ b/src/share/classes/javax/management/timer/Timer.java	Wed May 11 20:18:13 2011 -0400
@@ -26,6 +26,7 @@
 package javax.management.timer;
 
 import static com.sun.jmx.defaults.JmxProperties.TIMER_LOGGER;
+import java.util.ArrayList;
 import java.util.Date;
 import java.util.Hashtable;
 import java.util.Iterator;
@@ -1003,7 +1004,10 @@
         Integer notifID;
         Date date;
 
-        for (Object[] obj : timerTable.values()) {
+        ArrayList<Object[]> values =
+            new ArrayList<Object[]>(timerTable.values());
+
+        for (Object[] obj : values) {
 
             // Retrieve the timer notification and the date notification.
             //

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/javax/management/timer/StartTest.java	Wed May 11 20:18:13 2011 -0400
@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2008, 2011, 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.
+ */
+
+/*
+ * @bug 6659215
+ * @summary Test on timer start method with past notifications
+ * @author Shanliang JIANG
+ * @run clean StartTest
+ * @run build StartTest
+ * @run main StartTest
+ */
+
+import java.util.Date;
+import javax.management.timer.Timer;
+import javax.management.Notification;
+import javax.management.NotificationListener;
+
+public class StartTest {
+    public static void main(String[] args) throws Exception {
+        System.out.println(
+            ">>> Test on timer start method with past notifications.");
+
+        System.out.println(">>> Create a Timer object.");
+        Timer timer = new Timer();
+
+        System.out.println(
+            ">>> Set the flag (setSendPastNotification) to true.");
+        timer.setSendPastNotifications(true);
+
+        timer.addNotificationListener(myListener, null, null);
+
+        System.out.println(">>> Add notifications: " + SENT);
+
+        Date date = new Date();
+        for (int i = 0; i < SENT; i++) {
+            timer.addNotification(
+                "testType" + i, "testMsg" + i, "testData" + i, date);
+        }
+
+        System.out.println(">>> The notifications should be sent at " + date);
+        System.out.println(">>> Sleep 100 ms to have past notifications.");
+        Thread.sleep(100);
+
+        System.out.println(">>> Start the timer at " + new Date());
+        timer.start();
+
+        System.out.println(">>> Stop the timer.");
+        Thread.sleep(100);
+        stopping = true;
+        timer.stop();
+
+        if (received != SENT) {
+            throw new RuntimeException(
+                "Expected to receive " + SENT + " but got " + received);
+        }
+
+        System.out.println(">>> Received all expected notifications.");
+
+        System.out.println(">>> Bye bye!");
+    }
+
+    private static NotificationListener myListener =
+        new NotificationListener() {
+            public void handleNotification(Notification n, Object hb) {
+                if (!stopping) {
+                    received++;
+                    System.out.println(
+                        ">>> myListener-handleNotification: received " +
+                        n.getSequenceNumber());
+            }
+        }
+    };
+
+    private static int SENT = 10;
+    private static volatile int received = 0;
+    private static volatile boolean stopping = false;
+}