HBASE-24328 skip duplicate GCMultipleMergedRegionsProcedure while pre…

…vious finished (#1629)

Signed-off-by: huaxiangsun <huaxiangsun@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/GCMultipleMergedRegionsProcedure.java

@@ -97,7 +97,16 @@ protected Flow executeFromState(MasterProcedureEnv env, GCMergedRegionsState sta
     try {
       switch (state) {
         case GC_MERGED_REGIONS_PREPARE:
-          // Nothing to do to prepare.
+          // If GCMultipleMergedRegionsProcedure processing is slower than the CatalogJanitor's scan
+          // interval, it will end resubmitting GCMultipleMergedRegionsProcedure for the same
+          // region, we can skip duplicate GCMultipleMergedRegionsProcedure while previous finished
+          List<RegionInfo> parents = MetaTableAccessor.getMergeRegions(
+            env.getMasterServices().getConnection(), mergedChild.getRegionName());
+          if (parents == null || parents.isEmpty()) {
+            LOG.info("Region=" + mergedChild.getShortNameToLog()
+                + " info:merge qualifier has been deleted");
+            return Flow.NO_MORE_STATE;
+          }
           setNextState(GCMergedRegionsState.GC_MERGED_REGIONS_PURGE);
           break;
         case GC_MERGED_REGIONS_PURGE: