7068328: BufferPoolMXBean and PlatformLoggingMXBean getObjectName may return null

Reviewed-by: alanb
Contributed-by: spoole@uk.ibm.com

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

@@ -171,7 +171,8 @@ public class ManagementFactoryHelper {
             ObjectName result = objname;
             if (result == null) {
                 synchronized (this) {
-                    if (objname == null) {
+                    result = objname;
+                    if (result == null) {
                         result = Util.newObjectName(LOGGING_MXBEAN_NAME);
                         objname = result;
                     }
@@ -228,7 +229,8 @@ public class ManagementFactoryHelper {
                 ObjectName result = objname;
                 if (result == null) {
                     synchronized (this) {
-                        if (objname == null) {
+                        result = objname;
+                        if (result == null) {
                             result = Util.newObjectName(BUFFER_POOL_MXBEAN_NAME +
                                 ",name=" + pool.getName());
                             objname = result;

test/java/lang/management/ManagementFactory/GetObjectName.java

+/*
+ * Copyright (c) 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.
+ */
+
+/* @test
+ * @bug 7068328
+ * @summary Test if getObjectName handles properly when called by
+ *          multiple threads simultaneously. Run in othervm mode to
+ *          make sure the object name is not initialized to begin with.
+ * @run main/othervm GetObjectName
+ */
+
+import java.lang.management.BufferPoolMXBean;
+import java.lang.management.ManagementFactory;
+import java.lang.management.PlatformLoggingMXBean;
+import java.lang.management.PlatformManagedObject;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+public class GetObjectName {
+    private static boolean failed = false;
+    public static void main(String[] args) throws Exception {
+        int tasks = 10000;
+        ExecutorService executor = Executors.newFixedThreadPool(10);
+        submitTasks(executor, tasks);
+        executor.shutdown();
+        executor.awaitTermination(10, TimeUnit.SECONDS);
+        if (!failed) {
+            System.out.println("Test passed.");
+        }
+    }
+
+    static void submitTasks(ExecutorService executor, int count) {
+        for (int i=0; i < count && !failed; i++) {
+            executor.execute(new Runnable() {
+                @Override
+                public void run() {
+                    List<PlatformManagedObject> mbeans = new ArrayList<>();
+                    mbeans.add(ManagementFactory.getPlatformMXBean(PlatformLoggingMXBean.class));
+                    mbeans.addAll(ManagementFactory.getPlatformMXBeans(BufferPoolMXBean.class));
+                    for (PlatformManagedObject pmo : mbeans) {
+                        // Name should not be null
+                        if (pmo.getObjectName() == null) {
+                            failed = true;
+                            throw new RuntimeException("TEST FAILED: getObjectName() returns null");
+                        }
+                    }
+                }
+            });
+        }
+    }
+}