[GitHub] [hbase] ndimiduk commented on a change in pull request #1922: HBASE-24583 Normalizer can't actually merge empty regions when neighbor is larger than average size

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ndimiduk commented on a change in pull request #1922:
URL: https://github.com/apache/hbase/pull/1922#discussion_r443876595



##########
File path: 
hbase-server/src/main/java/org/apache/hadoop/hbase/master/normalizer/SimpleRegionNormalizer.java
##########
@@ -369,7 +369,8 @@ private boolean skipForMerge(final RegionStates 
regionStates, final RegionInfo r
       }
       final long currentSizeMb = getRegionSizeMB(current);
       final long nextSizeMb = getRegionSizeMB(next);
-      if (currentSizeMb + nextSizeMb < avgRegionSizeMb) {
+      // always merge away empty regions when they present themselves.
+      if (currentSizeMb == 0 || nextSizeMb == 0 || currentSizeMb + nextSizeMb 
< avgRegionSizeMb) {

Review comment:
       I like this idea of a fuzzy threshold idea. What if we merge a little 
more aggressively, expressed relative to `avgRegionSizeMb`? Something like
   
   ```
   if (currentSizeMb + nextSizeMb < avgRegionSizeMb * 0.4) {...}
   ```
   
   This gives us a strong preference toward larger regions, with a threshold 
based on the average size.
   
   I guess next you'll same "make it configurable" :)




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