HBASE-27713 Remove numRegions in Region Metrics

Author: thangTang

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionAggregateSource.java

@@ -47,9 +47,6 @@ public interface MetricsRegionAggregateSource extends BaseSource {
    */
   String METRICS_JMX_CONTEXT = "RegionServer,sub=" + METRICS_NAME;
 
-  String NUM_REGIONS = "numRegions";
-  String NUMBER_OF_REGIONS_DESC = "Number of regions in the metrics system";
-
   /**
    * Register a MetricsRegionSource as being open.
    * @param source the source for the region being opened.

hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionAggregateSourceImpl.java

@@ -22,7 +22,6 @@
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.TimeUnit;
 import org.apache.hadoop.hbase.metrics.BaseSourceImpl;
-import org.apache.hadoop.hbase.metrics.Interns;
 import org.apache.hadoop.metrics2.MetricsCollector;
 import org.apache.hadoop.metrics2.MetricsRecordBuilder;
 import org.apache.hadoop.metrics2.impl.JmxCacheBuster;
@@ -99,7 +98,6 @@ public void getMetrics(MetricsCollector collector, boolean all) {
           ((MetricsRegionSourceImpl) regionMetricSource).snapshot(mrb, all);
         }
       }
-      mrb.addGauge(Interns.info(NUM_REGIONS, NUMBER_OF_REGIONS_DESC), regionSources.size());
       metricsRegistry.snapshot(mrb, all);
     }
   }