7164191: properties.putAll API may fail with ConcurrentModifcationException on...

7164191: properties.putAll API may fail with ConcurrentModifcationException on multi-thread scenario
Reviewed-by: dholmes, sla
Contributed-by: NDeven You <youdwei@linux.vnet.ibm.com>

src/share/classes/sun/management/Agent.java

@@ -168,7 +168,10 @@ public class Agent {
 
         // management properties can be overridden by system properties
         // which take precedence
-        configProps.putAll(System.getProperties());
+        Properties sysProps = System.getProperties();
+        synchronized(sysProps){
+            configProps.putAll(sysProps);
+        }
 
         // if user specifies config file into command line for either
         // jcmd utilities or attach command it overrides properties set in
@@ -264,7 +267,10 @@ public class Agent {
 
         // management properties can be overridden by system properties
         // which take precedence
-        props.putAll(System.getProperties());
+        Properties sysProps = System.getProperties();
+        synchronized(sysProps){
+            props.putAll(sysProps);
+        }
 
         return props;
    }

test/sun/management/AgentCMETest.java

+/*
+ * 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
+ */
+
+/**
+ * @test
+ * @bug 7164191
+ * @summary properties.putAll API may fail with ConcurrentModifcationException on multi-thread scenario
+ * @author Deven You
+ */
+
+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 {
+        System.out.println("Start...");
+
+        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) {
+                        // do nothing
+                    }
+                }
+            }
+        });
+        t1.start();
+
+        for (int i = 0; i < 10000; i++) {
+            Agent.loadManagementProperties();
+        }
+
+        System.out.println("Finished...");
+    }
+}