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Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2020/05/29 09:51:23 UTC
[GitHub] [flink] zentol commented on a change in pull request #11586: [FLINK-5552][runtime] make JMXServer static per JVM
zentol commented on a change in pull request #11586:
URL: https://github.com/apache/flink/pull/11586#discussion_r432371112
##########
File path: flink-core/src/main/java/org/apache/flink/configuration/JMXServerOptions.java
##########
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.configuration;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.annotation.docs.Documentation;
+
+import static org.apache.flink.configuration.ConfigOptions.key;
+
+/**
+ * The set of configuration options relating to heartbeat manager settings.
+ */
+@PublicEvolving
+public class JMXServerOptions {
+
+ /** Port configured to enable JMX server for metrics and debugging. */
+ @Documentation.Section(Documentation.Sections.EXPERT_DEBUGGING_AND_TUNING)
+ public static final ConfigOption<String>JMX_SERVER_PORT =
+ key("jmx.server.port")
+ .defaultValue("-1")
Review comment:
having no default value at all would make this easier to understand imo
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
+ private static final Logger LOG = LoggerFactory.getLogger(JMXServer.class);
+
+ private static JMXServer instance = null;
+
+ private final AtomicReference<Remote> rmiServerReference = new AtomicReference<>();
+
+ private Registry rmiRegistry;
+ private JMXConnectorServer connector;
+ private int port;
+
+ /**
+ * Construct a new JMV-wide JMX server or acquire existing JMX server.
+ *
+ * <p>If JMXServer static instance is already constructed, it will not be
+ * reconstruct again. Instead a warning sign will be posted if the desired
+ * port configuration doesn't match the existing JMXServer static instance.
+ *
+ * @param portsConfig port configuration of the JMX server.
+ * @return JMXServer static instance.
+ */
+ public static JMXServer startInstance(String portsConfig) {
+ if (instance == null) {
+ if (!portsConfig.equals(JMXServerOptions.JMX_SERVER_PORT.defaultValue())) {
+ instance = startJMXServerWithPortRanges(portsConfig);
+ } else {
+ LOG.warn("JMX Server start failed. No explicit JMX port is configured.");
+ instance = null;
+ }
+ } else {
+ LOG.warn("JVM-wide JMXServer already started at port: " + instance.port);
+ }
+ return instance;
+ }
+
+ /**
+ * Acquire existing JMX server. or null if not started.
+ *
+ * @return the JMXServer static instance.
+ */
+ public static JMXServer getInstance() {
+ return instance;
+ }
+
+ /**
+ * Stop the JMX server.
+ */
+ public static void stopInstance() throws IOException {
+ if (instance != null) {
+ instance.stop();
+ instance = null;
+ }
+ }
+
+ public static int getPort() {
Review comment:
return an Optional<Integer> instead, then you can probably also get rid of `JMXServer#getInstance`
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
+ private static final Logger LOG = LoggerFactory.getLogger(JMXServer.class);
+
+ private static JMXServer instance = null;
+
+ private final AtomicReference<Remote> rmiServerReference = new AtomicReference<>();
+
+ private Registry rmiRegistry;
+ private JMXConnectorServer connector;
+ private int port;
+
+ /**
+ * Construct a new JMV-wide JMX server or acquire existing JMX server.
+ *
+ * <p>If JMXServer static instance is already constructed, it will not be
+ * reconstruct again. Instead a warning sign will be posted if the desired
Review comment:
```suggestion
* reconstructed again. Instead a warning will be logged if the given
```
##########
File path: flink-annotations/src/main/java/org/apache/flink/annotation/docs/Documentation.java
##########
@@ -82,6 +82,7 @@
public static final String STATE_BACKEND_ROCKSDB = "state_backend_rocksdb";
public static final String EXPERT_CLASS_LOADING = "expert_class_loading";
+ public static final String EXPERT_DEBUGGING_AND_TUNING = "expert_debugging_and_tuning";
Review comment:
the new section must be integrated into the documentation, by embedding the resulting .html file.
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
+ private static final Logger LOG = LoggerFactory.getLogger(JMXServer.class);
+
+ private static JMXServer instance = null;
+
+ private final AtomicReference<Remote> rmiServerReference = new AtomicReference<>();
+
+ private Registry rmiRegistry;
+ private JMXConnectorServer connector;
+ private int port;
+
+ /**
+ * Construct a new JMV-wide JMX server or acquire existing JMX server.
+ *
+ * <p>If JMXServer static instance is already constructed, it will not be
+ * reconstruct again. Instead a warning sign will be posted if the desired
+ * port configuration doesn't match the existing JMXServer static instance.
+ *
+ * @param portsConfig port configuration of the JMX server.
+ * @return JMXServer static instance.
+ */
+ public static JMXServer startInstance(String portsConfig) {
+ if (instance == null) {
+ if (!portsConfig.equals(JMXServerOptions.JMX_SERVER_PORT.defaultValue())) {
+ instance = startJMXServerWithPortRanges(portsConfig);
+ } else {
+ LOG.warn("JMX Server start failed. No explicit JMX port is configured.");
+ instance = null;
+ }
+ } else {
+ LOG.warn("JVM-wide JMXServer already started at port: " + instance.port);
+ }
+ return instance;
+ }
+
+ /**
+ * Acquire existing JMX server. or null if not started.
+ *
+ * @return the JMXServer static instance.
+ */
+ public static JMXServer getInstance() {
+ return instance;
+ }
+
+ /**
+ * Stop the JMX server.
+ */
+ public static void stopInstance() throws IOException {
+ if (instance != null) {
+ instance.stop();
+ instance = null;
+ }
+ }
+
+ public static int getPort() {
+ if (instance != null) {
+ return instance.port;
+ } else {
+ return -1;
+ }
+ }
+
+ private static JMXServer startJMXServerWithPortRanges(String portsConfig) {
+ Iterator<Integer> ports = NetUtils.getPortRangeFromString(portsConfig);
Review comment:
I'd move this into `#startInstance`; if portsConfig is an empty string then the iterator is empty, allowing you to easily check for the port to not be configured.
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
+ private static final Logger LOG = LoggerFactory.getLogger(JMXServer.class);
+
+ private static JMXServer instance = null;
+
+ private final AtomicReference<Remote> rmiServerReference = new AtomicReference<>();
+
+ private Registry rmiRegistry;
+ private JMXConnectorServer connector;
+ private int port;
+
+ /**
+ * Construct a new JMV-wide JMX server or acquire existing JMX server.
+ *
+ * <p>If JMXServer static instance is already constructed, it will not be
+ * reconstruct again. Instead a warning sign will be posted if the desired
+ * port configuration doesn't match the existing JMXServer static instance.
+ *
+ * @param portsConfig port configuration of the JMX server.
+ * @return JMXServer static instance.
+ */
+ public static JMXServer startInstance(String portsConfig) {
+ if (instance == null) {
+ if (!portsConfig.equals(JMXServerOptions.JMX_SERVER_PORT.defaultValue())) {
+ instance = startJMXServerWithPortRanges(portsConfig);
+ } else {
+ LOG.warn("JMX Server start failed. No explicit JMX port is configured.");
+ instance = null;
+ }
+ } else {
+ LOG.warn("JVM-wide JMXServer already started at port: " + instance.port);
+ }
+ return instance;
+ }
+
+ /**
+ * Acquire existing JMX server. or null if not started.
+ *
+ * @return the JMXServer static instance.
+ */
+ public static JMXServer getInstance() {
Review comment:
return an Optional<JMXServer> instead
##########
File path: flink-runtime/src/test/java/org/apache/flink/runtime/management/JMXServerTest.java
##########
@@ -0,0 +1,122 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.junit.Test;
+
+import javax.management.InstanceNotFoundException;
+import javax.management.MBeanServer;
+import javax.management.MBeanServerConnection;
+import javax.management.ObjectName;
+import javax.management.remote.JMXConnector;
+import javax.management.remote.JMXConnectorFactory;
+import javax.management.remote.JMXServiceURL;
+
+import java.lang.management.ManagementFactory;
+import java.net.ServerSocket;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+import static org.junit.Assert.assertTrue;
+
+/**
+ * Tests for the JMXServer.
+ */
+public class JMXServerTest {
+
+ /**
+ * Verifies initialize with port range.
+ */
+ @Test
+ public void testJMXServerInit() throws Exception {
+ try {
+ JMXServer.startInstance("23456-23466");
+ assertNotNull(JMXServer.getInstance());
+ } finally {
+ JMXServer.stopInstance();
+ }
+ }
+
+ /**
+ * Verifies initialize failure with occupied port.
+ */
+ @Test
+ public void testJMXServerInitWithInvalidPorts() throws Exception {
+ try {
+ ServerSocket socket = new ServerSocket(23456);
+ assertEquals(23456, socket.getLocalPort());
+ JMXServer.startInstance("23456");
+ assertNull(JMXServer.getInstance());
Review comment:
this line should never be reached
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
Review comment:
I'd say that the JMXServer itself should not have the singleton logic, and instead have something like a SingletonHolder object for that stuff.
There is for example no reason why the tests should work with a singleton; this usually just leads to issues.
##########
File path: flink-core/src/main/java/org/apache/flink/configuration/JMXServerOptions.java
##########
@@ -0,0 +1,46 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.configuration;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.annotation.docs.Documentation;
+
+import static org.apache.flink.configuration.ConfigOptions.key;
+
+/**
+ * The set of configuration options relating to heartbeat manager settings.
Review comment:
needs an update
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
+ private static final Logger LOG = LoggerFactory.getLogger(JMXServer.class);
+
+ private static JMXServer instance = null;
+
+ private final AtomicReference<Remote> rmiServerReference = new AtomicReference<>();
+
+ private Registry rmiRegistry;
+ private JMXConnectorServer connector;
+ private int port;
+
+ /**
+ * Construct a new JMV-wide JMX server or acquire existing JMX server.
+ *
+ * <p>If JMXServer static instance is already constructed, it will not be
+ * reconstruct again. Instead a warning sign will be posted if the desired
+ * port configuration doesn't match the existing JMXServer static instance.
+ *
+ * @param portsConfig port configuration of the JMX server.
+ * @return JMXServer static instance.
+ */
+ public static JMXServer startInstance(String portsConfig) {
Review comment:
these methods should be made thread-safe, otherwise you can end up starting 2 servers and never shutting one of them down.
##########
File path: flink-runtime/src/main/java/org/apache/flink/runtime/management/JMXServer.java
##########
@@ -0,0 +1,239 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.runtime.management;
+
+import org.apache.flink.configuration.JMXServerOptions;
+import org.apache.flink.util.NetUtils;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import javax.management.remote.JMXConnectorServer;
+import javax.management.remote.JMXServiceURL;
+import javax.management.remote.rmi.RMIConnectorServer;
+import javax.management.remote.rmi.RMIJRMPServerImpl;
+
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.net.MalformedURLException;
+import java.rmi.NoSuchObjectException;
+import java.rmi.NotBoundException;
+import java.rmi.Remote;
+import java.rmi.RemoteException;
+import java.rmi.registry.Registry;
+import java.rmi.server.UnicastRemoteObject;
+import java.util.Iterator;
+import java.util.concurrent.atomic.AtomicReference;
+
+
+/**
+ * JMX Server implementation that JMX clients can connect to.
+ *
+ * <p>Heavily based on j256 simplejmx project
+ *
+ * <p>https://github.com/j256/simplejmx/blob/master/src/main/java/com/j256/simplejmx/server/JmxServer.java
+ */
+public class JMXServer {
Review comment:
This should have a private constructor if all instantiations are supposed to go through `startInstance`. If not, then an explicit constructor might clarify things a bit.
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