6566891: RMIConnector: map value referencing map key in WeakHashMap prevents...

6566891: RMIConnector: map value referencing map key in WeakHashMap prevents map entry to be removed
Reviewed-by: egahlin, jbachorik, dfuchs, dholmes

src/share/classes/javax/management/remote/rmi/RMIConnector.java

@@ -405,14 +405,7 @@ public class RMIConnector implements JMXConnector, Serializable, JMXAddressable
             throw new IOException("Not connected");
         }
 
-        MBeanServerConnection rmbsc = rmbscMap.get(delegationSubject);
-        if (rmbsc != null) {
-            return rmbsc;
-        }
-
-        rmbsc = new RemoteMBeanServerConnection(delegationSubject);
-        rmbscMap.put(delegationSubject, rmbsc);
-        return rmbsc;
+        return getConnectionWithSubject(delegationSubject);
     }
 
     public void
@@ -1831,7 +1824,7 @@ public class RMIConnector implements JMXConnector, Serializable, JMXAddressable
 
     // Initialization of transient variables.
     private void initTransients() {
-        rmbscMap = new WeakHashMap<Subject, MBeanServerConnection>();
+        rmbscMap = new WeakHashMap<Subject, WeakReference<MBeanServerConnection>>();
         connected = false;
         terminated = false;
 
@@ -2011,6 +2004,25 @@ public class RMIConnector implements JMXConnector, Serializable, JMXAddressable
         private final ClassLoader loader;
     }
 
+    private MBeanServerConnection getConnectionWithSubject(Subject delegationSubject) {
+        MBeanServerConnection conn = null;
+
+        if (delegationSubject == null) {
+            if (nullSubjectConnRef == null
+                    || (conn = nullSubjectConnRef.get()) == null) {
+                conn = new RemoteMBeanServerConnection(null);
+                nullSubjectConnRef = new WeakReference(conn);
+            }
+        } else {
+            WeakReference<MBeanServerConnection> wr = rmbscMap.get(delegationSubject);
+            if (wr == null || (conn = wr.get()) == null) {
+                conn = new RemoteMBeanServerConnection(delegationSubject);
+                rmbscMap.put(delegationSubject, new WeakReference(conn));
+            }
+        }
+        return conn;
+    }
+
     /*
        The following section of code avoids a class loading problem
        with RMI.  The problem is that an RMI stub, when deserializing
@@ -2551,7 +2563,8 @@ public class RMIConnector implements JMXConnector, Serializable, JMXAddressable
 
     private transient long clientNotifSeqNo = 0;
 
-    private transient WeakHashMap<Subject, MBeanServerConnection> rmbscMap;
+    private transient WeakHashMap<Subject, WeakReference<MBeanServerConnection>> rmbscMap;
+    private transient WeakReference<MBeanServerConnection> nullSubjectConnRef = null;
 
     private transient RMINotifClient rmiNotifClient;
     // = new RMINotifClient(new Integer(0));

test/javax/management/remote/mandatory/connection/RMIConnectorInternalMapTest.java

+/*
+ * Copyright (c) 2013, 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.
+ */
+
+import java.lang.management.ManagementFactory;
+import java.lang.ref.WeakReference;
+import java.lang.reflect.Field;
+import java.util.Collections;
+import java.util.Map;
+import javax.management.MBeanServer;
+import javax.management.MBeanServerConnection;
+import javax.management.remote.JMXConnector;
+import javax.management.remote.JMXConnectorFactory;
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXConnectorServerFactory;
+import javax.management.remote.JMXPrincipal;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnector;
+import javax.security.auth.Subject;
+
+/*
+ * @test
+ * @bug 6566891
+ * @summary Check no memory leak on RMIConnector's rmbscMap
+ * @author Shanliang JIANG
+ * @run clean RMIConnectorInternalMapTest
+ * @run build RMIConnectorInternalMapTest
+ * @run main RMIConnectorInternalMapTest
+ */
+
+public class RMIConnectorInternalMapTest {
+    public static void main(String[] args) throws Exception {
+        System.out.println("---RMIConnectorInternalMapTest starting...");
+
+        JMXConnectorServer connectorServer = null;
+        JMXConnector connectorClient = null;
+
+        try {
+            MBeanServer mserver = ManagementFactory.getPlatformMBeanServer();
+            JMXServiceURL serverURL = new JMXServiceURL("rmi", "localhost", 0);
+            connectorServer = JMXConnectorServerFactory.newJMXConnectorServer(serverURL, null, mserver);
+            connectorServer.start();
+
+            JMXServiceURL serverAddr = connectorServer.getAddress();
+            connectorClient = JMXConnectorFactory.connect(serverAddr, null);
+            connectorClient.connect();
+
+            Field rmbscMapField = RMIConnector.class.getDeclaredField("rmbscMap");
+            rmbscMapField.setAccessible(true);
+            Map<Subject, WeakReference<MBeanServerConnection>> map =
+                    (Map<Subject, WeakReference<MBeanServerConnection>>) rmbscMapField.get(connectorClient);
+            if (map != null && !map.isEmpty()) { // failed
+                throw new RuntimeException("RMIConnector's rmbscMap must be empty at the initial time.");
+            }
+
+            Subject delegationSubject =
+                    new Subject(true,
+                    Collections.singleton(new JMXPrincipal("delegate")),
+                    Collections.EMPTY_SET,
+                    Collections.EMPTY_SET);
+            MBeanServerConnection mbsc1 =
+                    connectorClient.getMBeanServerConnection(delegationSubject);
+            MBeanServerConnection mbsc2 =
+                    connectorClient.getMBeanServerConnection(delegationSubject);
+
+            if (mbsc1 == null) {
+                throw new RuntimeException("Got null connection.");
+            }
+            if (mbsc1 != mbsc2) {
+                throw new RuntimeException("Not got same connection with a same subject.");
+            }
+
+            map = (Map<Subject, WeakReference<MBeanServerConnection>>) rmbscMapField.get(connectorClient);
+            if (map == null || map.isEmpty()) { // failed
+                throw new RuntimeException("RMIConnector's rmbscMap has wrong size "
+                        + "after creating a delegated connection.");
+            }
+
+            delegationSubject = null;
+            mbsc1 = null;
+            mbsc2 = null;
+
+            int i = 0;
+            while (!map.isEmpty() && i++ < 60) {
+                System.gc();
+                Thread.sleep(100);
+            }
+            System.out.println("---GC times: " + i);
+
+            if (!map.isEmpty()) {
+                throw new RuntimeException("Failed to clean RMIConnector's rmbscMap");
+            } else {
+                System.out.println("---RMIConnectorInternalMapTest: PASSED!");
+            }
+        } finally {
+            try {
+                connectorClient.close();
+                connectorServer.stop();
+            } catch (Exception e) {
+            }
+        }
+    }
+}

test/javax/management/remote/mandatory/connection/RMIConnectorNullSubjectConnTest.java

+/*
+ * Copyright (c) 2013, 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.
+ */
+
+import java.lang.management.ManagementFactory;
+import java.lang.ref.WeakReference;
+import java.lang.reflect.Field;
+import javax.management.MBeanServer;
+import javax.management.MBeanServerConnection;
+import javax.management.remote.JMXConnector;
+import javax.management.remote.JMXConnectorFactory;
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXConnectorServerFactory;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnector;
+
+/*
+ * @test
+ * @bug 6566891
+ * @summary Check no memory leak on RMIConnector's nullSubjectConn
+ * @author Shanliang JIANG
+ * @run clean RMIConnectorNullSubjectConnTest
+ * @run build RMIConnectorNullSubjectConnTest
+ * @run main RMIConnectorNullSubjectConnTest
+ */
+
+public class RMIConnectorNullSubjectConnTest {
+    public static void main(String[] args) throws Exception {
+        System.out.println("---RMIConnectorNullSubjectConnTest starting...");
+
+        JMXConnectorServer connectorServer = null;
+        JMXConnector connectorClient = null;
+
+        try {
+            MBeanServer mserver = ManagementFactory.getPlatformMBeanServer();
+            JMXServiceURL serverURL = new JMXServiceURL("rmi", "localhost", 0);
+            connectorServer = JMXConnectorServerFactory.newJMXConnectorServer(serverURL, null, mserver);
+            connectorServer.start();
+
+            JMXServiceURL serverAddr = connectorServer.getAddress();
+            connectorClient = JMXConnectorFactory.connect(serverAddr, null);
+            connectorClient.connect();
+
+            Field nullSubjectConnField = RMIConnector.class.getDeclaredField("nullSubjectConnRef");
+            nullSubjectConnField.setAccessible(true);
+
+            WeakReference<MBeanServerConnection> weak =
+                    (WeakReference<MBeanServerConnection>)nullSubjectConnField.get(connectorClient);
+
+            if (weak != null && weak.get() != null) {
+                throw new RuntimeException("nullSubjectConnRef must be null at initial time.");
+            }
+
+            MBeanServerConnection conn1 = connectorClient.getMBeanServerConnection(null);
+            MBeanServerConnection conn2 = connectorClient.getMBeanServerConnection(null);
+            if (conn1 == null) {
+                throw new RuntimeException("A connection with null subject should not be null.");
+            } else if (conn1 != conn2) {
+                throw new RuntimeException("The 2 connections with null subject are not equal.");
+            }
+
+            conn1 = null;
+            conn2 = null;
+            int i = 1;
+            do {
+                System.gc();
+                Thread.sleep(100);
+                weak = (WeakReference<MBeanServerConnection>)nullSubjectConnField.get(connectorClient);
+            } while ((weak != null && weak.get() != null) && i++ < 60);
+
+            System.out.println("---GC times: " + i);
+
+            if (weak != null && weak.get() != null) {
+                throw new RuntimeException("Failed to clean RMIConnector's nullSubjectConn");
+            } else {
+                System.out.println("---RMIConnectorNullSubjectConnTest: PASSED!");
+            }
+        } finally {
+            try {
+                connectorClient.close();
+                connectorServer.stop();
+            } catch (Exception e) {
+            }
+        }
+    }
+}