--- old/src/share/classes/sun/management/Agent.java	2012-04-11 14:48:00.217790277 +0800
+++ new/src/share/classes/sun/management/Agent.java	2012-04-11 14:48:00.045789432 +0800
@@ -264,8 +264,12 @@
 
         // management properties can be overridden by system properties
         // which take precedence
-        props.putAll(System.getProperties());
-
+        // putAll will fail if system properties are modified
+        // while copying them, so we need synchronize the system properties
+        Properties sysProps = System.getProperties();
+        synchronized (sysProps) {
+            props.putAll(sysProps);
+        }
         return props;
    }
 
--- /dev/null	2012-03-30 13:18:40.878240111 +0800
+++ new/test/sun/management/Agent/AgentCMETest.java	2012-04-11 14:48:00.609792226 +0800
@@ -0,0 +1,61 @@
+/*
+ * Copyright (c) 2012 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.
+ */
+
+/*
+ * Portions Copyright (c) 2012 IBM Corporation
+ */
+
+import java.util.Properties;
+import sun.management.Agent;
+
+public class AgentCMETest {
+	static Class<?> agentClass;
+
+	/**
+	 * In sun.management.Agent.loadManagementProperties(), call
+	 * properties.putAll API may fail with ConcurrentModifcationException if the
+	 * system properties are modified simultaneously by another thread
+	 *
+	 * @param args
+	 * @throws Exception
+	 */
+	public static void main(String[] args) throws Exception {
+		final Properties properties = System.getProperties();
+		Thread t1 = new Thread(new Runnable() {
+			public void run() {
+				for (int i = 0; i < 100; i++) {
+					properties.put(String.valueOf(i), "");
+					try {
+						Thread.sleep(1);
+					} catch (InterruptedException e) {
+					}
+				}
+			}
+		});
+		t1.start();
+
+		while (true) {
+			Agent.loadManagementProperties();
+		}
+	}
+}