[hotfix][metrics] Harden JMXAvailability test

flink-core/src/main/java/org/apache/flink/metrics/reporter/JMXReporter.java

@@ -125,6 +125,10 @@ public class JMXReporter implements MetricReporter {
 			}
 		}
 	}
+	
+	public int getPort() {
+		return jmxServer.port;
+	}
 
 	// ------------------------------------------------------------------------
 	//  adding / removing metrics
@@ -415,6 +419,7 @@ public class JMXReporter implements MetricReporter {
 	private static class JMXServer {
 		private Registry rmiRegistry;
 		private JMXConnectorServer connector;
+		private int port;
 
 		public void start(int port) throws IOException {
 			if (rmiRegistry != null && connector != null) {
@@ -423,6 +428,7 @@ public class JMXReporter implements MetricReporter {
 			}
 			startRmiRegistry(port);
 			startJmxService(port);
+			this.port = port;
 		}
 
 		/**

flink-core/src/test/java/org/apache/flink/metrics/reporter/JMXReporterTest.java

@@ -38,7 +38,6 @@ import javax.management.remote.JMXConnectorFactory;
 import javax.management.remote.JMXServiceURL;
 import java.lang.management.ManagementFactory;
 
-import static org.apache.flink.metrics.MetricRegistry.KEY_METRICS_JMX_PORT;
 import static org.apache.flink.metrics.MetricRegistry.KEY_METRICS_REPORTER_CLASS;
 import static org.junit.Assert.assertEquals;
 
@@ -137,16 +136,8 @@ public class JMXReporterTest extends TestLogger {
 		JMXReporter rep1 = new JMXReporter();
 		JMXReporter rep2 = new JMXReporter();
 
-		int port1 = 9010;
-		int port2 = 9011;
-
-		Configuration cfg1 = new Configuration();
-		cfg1.setString(KEY_METRICS_JMX_PORT, String.valueOf(port1));
-		Configuration cfg2 = new Configuration();
-		cfg2.setString(KEY_METRICS_JMX_PORT, String.valueOf(port2));
-
-		rep1.open(cfg1);
-		rep2.open(cfg2);
+		rep1.open(new Configuration());
+		rep2.open(new Configuration());
 
 		rep1.notifyOfAddedMetric(new Gauge<Integer>() {
 			@Override
@@ -165,7 +156,7 @@ public class JMXReporterTest extends TestLogger {
 		ObjectName objectName1 = new ObjectName(JMXReporter.generateJmxName("rep1", mg.getScopeComponents()));
 		ObjectName objectName2 = new ObjectName(JMXReporter.generateJmxName("rep2", mg.getScopeComponents()));
 
-		JMXServiceURL url1 = new JMXServiceURL("service:jmx:rmi://localhost:" + port1 + "/jndi/rmi://localhost:" + port1 + "/jmxrmi");
+		JMXServiceURL url1 = new JMXServiceURL("service:jmx:rmi://localhost:" + rep1.getPort() + "/jndi/rmi://localhost:" + rep1.getPort() + "/jmxrmi");
 		JMXConnector jmxCon1 = JMXConnectorFactory.connect(url1);
 		MBeanServerConnection mCon1 = jmxCon1.getMBeanServerConnection();
 
@@ -177,7 +168,7 @@ public class JMXReporterTest extends TestLogger {
 		jmxCon1 = null;
 		mCon1 = null;
 
-		JMXServiceURL url2 = new JMXServiceURL("service:jmx:rmi://localhost:" + port2 + "/jndi/rmi://localhost:" + port2 + "/jmxrmi");
+		JMXServiceURL url2 = new JMXServiceURL("service:jmx:rmi://localhost:" + rep2.getPort() + "/jndi/rmi://localhost:" + rep2.getPort() + "/jmxrmi");
 		JMXConnector jmxCon2 = JMXConnectorFactory.connect(url2);
 		MBeanServerConnection mCon2 = jmxCon2.getMBeanServerConnection();