YARN-8905. [Router] Add JvmMetricsInfo and pause monitor. Contributed by Bilwa S T.

(cherry picked from commit f84a278baad6cb871ea4196257f23a938826ca23)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/main/java/org/apache/hadoop/yarn/server/router/Router.java

@@ -24,7 +24,9 @@ import java.util.concurrent.atomic.AtomicBoolean;
 import org.apache.hadoop.classification.InterfaceAudience.Private;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
+import org.apache.hadoop.metrics2.source.JvmMetrics;
 import org.apache.hadoop.service.CompositeService;
+import org.apache.hadoop.util.JvmPauseMonitor;
 import org.apache.hadoop.util.ShutdownHookManager;
 import org.apache.hadoop.util.StringUtils;
 import org.apache.hadoop.yarn.YarnUncaughtExceptionHandler;
@@ -64,6 +66,7 @@ public class Router extends CompositeService {
   private static CompositeServiceShutdownHook routerShutdownHook;
   private Configuration conf;
   private AtomicBoolean isStopping = new AtomicBoolean(false);
+  private JvmPauseMonitor pauseMonitor;
   private RouterClientRMService clientRMProxyService;
   private RouterRMAdminService rmAdminProxyService;
   private WebApp webApp;
@@ -100,6 +103,11 @@ public class Router extends CompositeService {
         WebAppUtils.getRouterWebAppURLWithoutScheme(this.conf));
     // Metrics
     DefaultMetricsSystem.initialize(METRICS_NAME);
+    JvmMetrics jm = JvmMetrics.initSingleton("Router", null);
+    pauseMonitor = new JvmPauseMonitor();
+    addService(pauseMonitor);
+    jm.setPauseMonitor(pauseMonitor);
+
     super.serviceInit(conf);
   }
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-router/src/test/java/org/apache/hadoop/yarn/server/router/TestRouter.java

@@ -0,0 +1,38 @@
+/**
+ * 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.hadoop.yarn.server.router;
+
+import static org.junit.Assert.assertEquals;
+
+import org.apache.hadoop.yarn.conf.YarnConfiguration;
+import org.junit.Test;
+
+/**
+ * Tests {@link Router}.
+ */
+public class TestRouter {
+
+  @Test
+  public void testJVMMetricsService() {
+    YarnConfiguration conf = new YarnConfiguration();
+    Router router = new Router();
+    router.init(conf);
+    assertEquals(3, router.getServices().size());
+  }
+
+}