[GitHub] [hbase] mnpoonia commented on a change in pull request #931: HBASE-22285 A normalizer which merges small size regions with adjacen…

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mnpoonia commented on a change in pull request #931: HBASE-22285 A normalizer which merges small size regions with adjacen…
URL: https://github.com/apache/hbase/pull/931#discussion_r357963884
 
 

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 File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/MergeNormalizer.java
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 @@ -0,0 +1,154 @@
+package org.apache.hadoop.hbase.master.normalizer;
+
+import com.google.protobuf.ServiceException;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+import org.apache.hadoop.hbase.HBaseIOException;
+import org.apache.hadoop.hbase.HRegionInfo;
+import org.apache.hadoop.hbase.RegionLoad;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.classification.InterfaceAudience;
+import org.apache.hadoop.hbase.client.Admin;
+import org.apache.hadoop.hbase.master.MasterRpcServices;
+import org.apache.hadoop.hbase.master.MasterServices;
+import org.apache.hadoop.hbase.protobuf.RequestConverter;
+import java.sql.Timestamp;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+
+
+
+/**
+ * Implementation of MergeNormalizer
+ *
+ * Logic in use:
+ *
+ *  <ol>
+ *  <li> get all regions of a given table
+ *  <li> get avg size S of each region (by total size of store files reported in RegionLoad)
+ *  <li> Otherwise, two region R1 and its smallest neighbor R2 are merged,
+ *    if R1 + R1 &lt;  S, and all such regions are returned to be merged
+ *  <li> Otherwise, no action is performed
+ * </ol>
+ * <p>
+ * Region sizes are coarse and approximate on the order of megabytes. Also,
+ * empty regions (less than 1MB) are also merged if the age of region is &gt  MIN_DURATION_FOR_MERGE (default 2)
+ */
+
+@InterfaceAudience.Private
+public class MergeNormalizer implements RegionNormalizer {
+  private static final Log LOG = LogFactory.getLog(MergeNormalizer.class);
+  private static final int MIN_REGION_COUNT = 3;
+  private static final int MIN_DURATION_FOR_MERGE=2;
+  private MasterServices masterServices;
+  private MasterRpcServices masterRpcServices;
+
+  @Override public void setMasterServices(MasterServices masterServices) {
+    this.masterServices = masterServices;
+  }
+
+  @Override public void setMasterRpcServices(MasterRpcServices masterRpcServices) {
+    this.masterRpcServices = masterRpcServices;
+  }
+
+  @Override public List<NormalizationPlan> computePlanForTable(TableName table)
+    throws HBaseIOException {
+    if (table == null || table.isSystemTable()) {
+      LOG.debug("Normalization of system table " + table + " isn't allowed");
+      return null;
+    }
+    boolean mergeEnabled = true;
+    try {
+      mergeEnabled = masterRpcServices.isSplitOrMergeEnabled(null,
+        RequestConverter.buildIsSplitOrMergeEnabledRequest(Admin.MasterSwitchType.MERGE)).getEnabled();
+    } catch (ServiceException se) {
+      LOG.debug("Unable to determine whether merge is enabled", se);
 
 Review comment:
   I think we can make it WARN but not error. Its a valid scenario for table to disable merge and still at cluster level have normalizer enabled.

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