[GitHub] [hbase] saintstack commented on a change in pull request #1734: HBASE-24376 MergeNormalizer is merging non-adjacent regions and causi…

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saintstack commented on a change in pull request #1734:
URL: https://github.com/apache/hbase/pull/1734#discussion_r426900712



##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/AbstractRegionNormalizer.java
##########
@@ -170,6 +170,8 @@ private static boolean skipForMerge(final RegionState state) {
         + "number of regions: {}",
       table, avgRegionSize, table, tableRegions.size());
 
+    // Sorting based on RegionInfo.COMPARATOR.
+    tableRegions.sort(RegionInfo.COMPARATOR);

Review comment:
       Duh

##########
File path: hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/MergeNormalizationPlan.java
##########
@@ -69,8 +69,11 @@ public String toString() {
   public void execute(Admin admin) {
     LOG.info("Executing merging normalization plan: " + this);
     try {
+      // Do not use force=true as corner cases can happen, non adjacent regions,
+      // merge with a merged child region with no GC done yet, it is going to
+      // cause all different issues.
       admin.mergeRegionsAsync(firstRegion.getEncodedNameAsBytes(),
-        secondRegion.getEncodedNameAsBytes(), true);
+        secondRegion.getEncodedNameAsBytes(), false);

Review comment:
       Great




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