HDFS-17345. Add a metrics to record block report generating cost time. (#6475). Contributed by farmmamba.

Reviewed-by:  Shuyan Zhang <zhangshuyan@apache.org>
Signed-off-by:  Shuyan Zhang <zhangshuyan@apache.org>

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

@@ -458,6 +458,8 @@ Each metrics record contains tags such as SessionId and Hostname as additional i
 | `BlockReportsAvgTime` | Average time of block report operations in milliseconds |
 | `BlockReports`*ServiceId*`-`*NNId*`NumOps` | Total number of block report operations to specific serviceId and nnId |
 | `BlockReports`*ServiceId*`-`*NNId*`AvgTime` | Average time of block report operations to specific serviceId and nnId in milliseconds |
+| `BlockReportsCreateCostMillsNumOps` | Total number of block report creating operations |
+| `BlockReportsCreateCostMillsAvgTime` | Average time of block report creating operations in milliseconds |
 | `IncrementalBlockReportsNumOps` | Total number of incremental block report operations |
 | `IncrementalBlockReportsAvgTime` | Average time of incremental block report operations in milliseconds |
 | `IncrementalBlockReports`*ServiceId*`-`*NNId*`NumOps` | Total number of incremental block report operations to specific serviceId and nnId |

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java

@@ -452,6 +452,7 @@ class BPServiceActor implements Runnable {
       // Log the block report processing stats from Datanode perspective
       long brSendCost = monotonicNow() - brSendStartTime;
       long brCreateCost = brSendStartTime - brCreateStartTime;
+      dn.getMetrics().addBlockReportCreateCost(brCreateCost);
       dn.getMetrics().addBlockReport(brSendCost, getRpcMetricSuffix());
       final int nCmds = cmds.size();
       LOG.info((success ? "S" : "Uns") +

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/metrics/DataNodeMetrics.java

@@ -132,6 +132,7 @@ public class DataNodeMetrics {
   @Metric MutableRate heartbeatsTotal;
   @Metric MutableRate lifelines;
   @Metric MutableRate blockReports;
+  @Metric private MutableRate blockReportsCreateCostMills;
   @Metric MutableRate incrementalBlockReports;
   @Metric MutableRate cacheReports;
   @Metric MutableRate packetAckRoundTripTimeNanos;
@@ -321,6 +322,10 @@ public class DataNodeMetrics {
     }
   }
 
+  public void addBlockReportCreateCost(long latency) {
+    blockReportsCreateCostMills.add(latency);
+  }
+
   public void addIncrementalBlockReport(long latency,
       String rpcMetricSuffix) {
     incrementalBlockReports.add(latency);