HDFS-12883. RBF: Document Router and State Store metrics. Contributed by Yiqun Lin.

hadoop-common-project/hadoop-common/src/site/markdown/Metrics.md

@@ -419,6 +419,42 @@ contains tags such as Hostname as additional information along with metrics.
 | `FileIoErrorRateNumOps` | The number of file io error operations within an interval time of metric |
 | `FileIoErrorRateAvgTime` | It measures the mean time in milliseconds from the start of an operation to hitting a failure |
 
+RouterRPCMetrics
+----------------
+RouterRPCMetrics shows the statistics of the Router component in Router-based federation.
+
+| Name | Description |
+|:---- |:---- |
+| `ProcessingOp` | Number of operations the Router processed internally |
+| `ProxyOp` | Number of operations the Router proxied to a Namenode |
+| `ProxyOpFailureStandby` | Number of operations to fail to reach NN |
+| `ProxyOpFailureCommunicate` | Number of operations to hit a standby NN |
+| `ProxyOpNotImplemented` | Number of operations not implemented |
+| `RouterFailureStateStore` | Number of failed requests due to State Store unavailable |
+| `RouterFailureReadOnly` | Number of failed requests due to read only mount point |
+| `RouterFailureLocked` | Number of failed requests due to locked path |
+| `RouterFailureSafemode` | Number of failed requests due to safe mode |
+| `ProcessingNumOps` | Number of operations the Router processed internally within an interval time of metric |
+| `ProcessingAvgTime` | Average time for the Router to process operations in nanoseconds |
+| `ProxyNumOps` | Number of times of that the Router to proxy operations to the Namenodes within an interval time of metric |
+| `ProxyAvgTime` | Average time for the Router to proxy operations to the Namenodes in nanoseconds |
+
+StateStoreMetrics
+-----------------
+StateStoreMetrics shows the statistics of the State Store component in Router-based federation.
+
+| Name | Description |
+|:---- |:---- |
+| `ReadsNumOps` | Number of GET transactions for State Store within an interval time of metric |
+| `ReadsAvgTime` | Average time of GET transactions for State Store in milliseconds |
+| `WritesNumOps` | Number of PUT transactions for State Store within an interval time of metric |
+| `WritesAvgTime` | Average time of PUT transactions for State Store in milliseconds |
+| `RemovesNumOps` | Number of REMOVE transactions for State Store within an interval time of metric |
+| `RemovesAvgTime` | Average time of REMOVE transactions for State Store in milliseconds |
+| `FailuresNumOps` | Number of failed transactions for State Store within an interval time of metric |
+| `FailuresAvgTime` | Average time of failed transactions for State Store in milliseconds |
+| `Cache`*BaseRecord*`Size` | Number of store records to cache in State Store |
+
 yarn context
 ============
 

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/FederationRPCMetrics.java

@@ -34,7 +34,7 @@ import org.apache.hadoop.metrics2.lib.MutableRate;
  * Implementation of the RPC metrics collector.
  */
 @Metrics(name = "RouterRPCActivity", about = "Router RPC Activity",
-    context = "router")
+    context = "dfs")
 public class FederationRPCMetrics implements FederationRPCMBean {
 
   private final MetricsRegistry registry = new MetricsRegistry("router");

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/federation/metrics/StateStoreMetrics.java

@@ -38,7 +38,7 @@ import com.google.common.annotations.VisibleForTesting;
  * Implementations of the JMX interface for the State Store metrics.
  */
 @Metrics(name = "StateStoreActivity", about = "Router metrics",
-    context = "router")
+    context = "dfs")
 public final class StateStoreMetrics implements StateStoreMBean {
 
   private final MetricsRegistry registry = new MetricsRegistry("router");

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/HDFSRouterFederation.md

@@ -312,4 +312,10 @@ Monitor the namenodes in the subclusters for forwarding the client requests.
 | dfs.federation.router.heartbeat.enable | `true` | If `true`, the Router heartbeats into the State Store. |
 | dfs.federation.router.heartbeat.interval | 5000 | How often the Router should heartbeat into the State Store in milliseconds. |
 | dfs.federation.router.monitor.namenode | | The identifier of the namenodes to monitor and heartbeat. |
-| dfs.federation.router.monitor.localnamenode.enable | `true` | If `true`, the Router should monitor the namenode in the local machine. |
+| dfs.federation.router.monitor.localnamenode.enable | `true` | If `true`, the Router should monitor the namenode in the local machine. |
+
+Metrics
+-------
+
+The Router and State Store statistics are exposed in metrics/JMX. These info will be very useful for monitoring.
+More metrics info can see [Router RPC Metrics](../../hadoop-project-dist/hadoop-common/Metrics.html#RouterRPCMetrics) and [State Store Metrics](../../hadoop-project-dist/hadoop-common/Metrics.html#StateStoreMetrics).