HBASE-23561 acquire lock before update regionsMap (#1263)

Addendum: tie add and delete of regionMap and encodedRegionsMap

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

Author: mwkang

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

@@ -68,6 +68,8 @@ public int compare(final RegionState l, final RegionState r) {
   public final static RegionStateStampComparator REGION_STATE_STAMP_COMPARATOR =
     new RegionStateStampComparator();
 
+  private final Object regionsMapLock = new Object();
+
   // TODO: Replace the ConcurrentSkipListMaps
   /**
    * RegionName -- i.e. RegionInfo.getRegionName() -- as bytes to {@link RegionStateNode}
@@ -121,11 +123,12 @@ public boolean isRegionInRegionStates(final RegionInfo hri) {
   // RegionStateNode helpers
   // ==========================================================================
   RegionStateNode createRegionStateNode(RegionInfo regionInfo) {
-    return regionsMap.computeIfAbsent(regionInfo.getRegionName(), key -> {
-      final RegionStateNode node = new RegionStateNode(regionInfo, regionInTransition);
+    synchronized (regionsMapLock) {
+      RegionStateNode node = regionsMap.computeIfAbsent(regionInfo.getRegionName(),
+        key -> new RegionStateNode(regionInfo, regionInTransition));
       encodedRegionsMap.putIfAbsent(regionInfo.getEncodedName(), node);
       return node;
-    });
+    }
   }
 
   public RegionStateNode getOrCreateRegionStateNode(RegionInfo regionInfo) {
@@ -142,8 +145,10 @@ public RegionStateNode getRegionStateNode(RegionInfo regionInfo) {
   }
 
   public void deleteRegion(final RegionInfo regionInfo) {
-    regionsMap.remove(regionInfo.getRegionName());
-    encodedRegionsMap.remove(regionInfo.getEncodedName());
+    synchronized (regionsMapLock) {
+      regionsMap.remove(regionInfo.getRegionName());
+      encodedRegionsMap.remove(regionInfo.getEncodedName());
+    }
     // See HBASE-20860
     // After master restarts, merged regions' RIT state may not be cleaned,
     // making sure they are cleaned here