HADOOP-16435. RpcMetrics should not retained forever. Contributed by Zoltan Haindrich.

(cherry picked from commit cbfa3f3e988b8a3f142abadfe4f18201b6438ac9)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/metrics/RpcDetailedMetrics.java

@@ -82,5 +82,7 @@ public class RpcDetailedMetrics {
    * Shutdown the instrumentation for the process
    */
   //@Override // some instrumentation interface
-  public void shutdown() {}
+  public void shutdown() {
+    DefaultMetricsSystem.instance().unregisterSource(name);
+  }
 }

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/metrics/RpcMetrics.java

@@ -166,7 +166,9 @@ public class RpcMetrics {
    * Shutdown the instrumentation for the process
    */
   //@Override
-  public void shutdown() {}
+  public void shutdown() {
+    DefaultMetricsSystem.instance().unregisterSource(name);
+  }
 
   /**
    * Increment sent bytes by count

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/ipc/metrics/TestRpcMetrics.java

@@ -0,0 +1,60 @@
+/**
+ * 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.ipc.metrics;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.Writable;
+import org.apache.hadoop.ipc.RPC;
+import org.apache.hadoop.ipc.Server;
+import org.apache.hadoop.metrics2.MetricsSystem;
+import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
+import org.junit.Test;
+
+public class TestRpcMetrics {
+
+  @Test
+  public void metricsAreUnregistered() throws Exception {
+
+    Configuration conf = new Configuration();
+    Server server = new Server("0.0.0.0", 0, LongWritable.class, 1, conf) {
+      @Override
+      public Writable call(
+          RPC.RpcKind rpcKind, String protocol, Writable param,
+          long receiveTime) throws Exception {
+        return null;
+      }
+    };
+    MetricsSystem metricsSystem = DefaultMetricsSystem.instance();
+    RpcMetrics rpcMetrics = server.getRpcMetrics();
+    RpcDetailedMetrics rpcDetailedMetrics = server.getRpcDetailedMetrics();
+
+    assertNotNull(metricsSystem.getSource(rpcMetrics.name()));
+    assertNotNull(metricsSystem.getSource(rpcDetailedMetrics.name()));
+
+    server.stop();
+
+    assertNull(metricsSystem.getSource(rpcMetrics.name()));
+    assertNull(metricsSystem.getSource(rpcDetailedMetrics.name()));
+
+  }
+
+}