HBASE-25975 Row Commit Sequencer

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

@@ -38,6 +38,7 @@ public interface MetricsRegionSource extends Comparable<MetricsRegionSource> {
   String NUM_FILES_COMPACTED_COUNT = "numFilesCompactedCount";
   String FLUSHES_QUEUED_COUNT = "flushesQueuedCount";
   String MAX_FLUSH_QUEUE_SIZE = "maxFlushQueueSize";
+  String ROW_SEQUENCING_YIELDS = "rowSequencingYields";
   String COMPACTIONS_COMPLETED_DESC = "Number of compactions that have completed.";
   String COMPACTIONS_FAILED_DESC = "Number of compactions that have failed.";
   String LAST_MAJOR_COMPACTION_DESC = "Age of the last major compaction in milliseconds.";
@@ -57,6 +58,7 @@ public interface MetricsRegionSource extends Comparable<MetricsRegionSource> {
   String ROW_READS_ONLY_ON_MEMSTORE_DESC = "Row reads happening completely out of memstore";
   String MIXED_ROW_READS = "mixedRowReadsCount";
   String MIXED_ROW_READS_ON_STORE_DESC = "Row reads happening out of files and memstore on store";
+  String ROW_SEQUENCING_YIELDS_DESC = "Number of yields taken to sequence row commits";
 
   /**
    * Close the region's metrics as this region is closing.
@@ -99,5 +101,9 @@ public interface MetricsRegionSource extends Comparable<MetricsRegionSource> {
    */
   MetricsRegionAggregateSource getAggregateSource();
 
+  /**
+   * Update count of row sequencing yields.
+   */
+  void updateRowSequencingYields();
 
 }

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

@@ -57,7 +57,7 @@ public class MetricsRegionSourceImpl implements MetricsRegionSource {
   private final String regionIncrementKey;
   private final String regionAppendKey;
   private final String regionScanKey;
-
+  private final String regionRowSequencerYieldsKey;
   /*
    * Implementation note: Do not put histograms per region. With hundreds of regions in a server
    * histograms allocate too many counters. See HBASE-17016.
@@ -69,6 +69,8 @@ public class MetricsRegionSourceImpl implements MetricsRegionSource {
   private final MutableFastCounter regionGet;
   private final MutableFastCounter regionScan;
 
+  private final MutableFastCounter regionRowSequencerYields;
+
   private final int hashCode;
 
   public MetricsRegionSourceImpl(MetricsRegionWrapper regionWrapper,
@@ -107,6 +109,10 @@ public MetricsRegionSourceImpl(MetricsRegionWrapper regionWrapper,
 
     regionScanKey = regionNamePrefix + MetricsRegionServerSource.SCAN_KEY + suffix;
     regionScan = registry.getCounter(regionScanKey, 0L);
+
+    regionRowSequencerYieldsKey = regionNamePrefix + MetricsRegionSource.ROW_SEQUENCING_YIELDS +
+        suffix;
+    regionRowSequencerYields = registry.getCounter(regionRowSequencerYieldsKey, 0L);
   }
 
   @Override
@@ -135,6 +141,7 @@ public void close() {
       registry.removeMetric(regionAppendKey);
       registry.removeMetric(regionGetKey);
       registry.removeMetric(regionScanKey);
+      registry.removeMetric(regionRowSequencerYieldsKey);
 
       regionWrapper = null;
     }
@@ -170,6 +177,11 @@ public void updateAppend() {
     regionAppend.incr();
   }
 
+  @Override
+  public void updateRowSequencingYields() {
+    regionRowSequencerYields.incr();
+  }
+
   @Override
   public MetricsRegionAggregateSource getAggregateSource() {
     return agg;
@@ -302,6 +314,10 @@ void snapshot(MetricsRecordBuilder mrb, boolean ignored) {
               regionNamePrefix + MetricsRegionSource.MAX_FLUSH_QUEUE_SIZE,
               MetricsRegionSource.MAX_FLUSH_QUEUE_DESC),
           this.regionWrapper.getMaxFlushQueueSize());
+      mrb.addCounter(Interns.info(
+             regionNamePrefix + MetricsRegionSource.ROW_SEQUENCING_YIELDS,
+             MetricsRegionSource.ROW_SEQUENCING_YIELDS_DESC),
+          this.regionWrapper.getRowSequencingYields());
       addCounter(mrb, this.regionWrapper.getMemstoreOnlyRowReadsCount(),
         MetricsRegionSource.ROW_READS_ONLY_ON_MEMSTORE,
         MetricsRegionSource.ROW_READS_ONLY_ON_MEMSTORE_DESC);

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

@@ -183,4 +183,8 @@ public interface MetricsRegionWrapper {
    */
   Map<String, Long> getMixedRowReadsCount();
 
+  /**
+   * @return the number of yields made for row sequencing
+   */
+  long getRowSequencingYields();
 }

hbase-hadoop-compat/src/test/java/org/apache/hadoop/hbase/regionserver/TestMetricsRegionSourceImpl.java

@@ -233,5 +233,10 @@ public Map<String, Long> getMixedRowReadsCount() {
       map.put("info", 0L);
       return map;
     }
+
+    @Override
+    public long getRowSequencingYields() {
+      return 0;
+    }
   }
 }