HBASE-27758 Inconsistent synchronization in MetricsUserSourceImpl (ap…

…ache#5149)

Signed-off-by: Duo Zhang <zhangduo@apache.org>
(cherry picked from commit dedf1f9)
Change-Id: I22c87caa97668aff7b7789aebb47e7dce9469789

hbase-hadoop2-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsUserSourceImpl.java

@@ -135,15 +135,13 @@ public MetricsUserSourceImpl(String user, MetricsUserAggregateSourceImpl agg) {
 
   @Override
   public void register() {
-    synchronized (this) {
-      getHisto = registry.newTimeHistogram(userGetKey);
-      scanTimeHisto = registry.newTimeHistogram(userScanTimeKey);
-      putHisto = registry.newTimeHistogram(userPutKey);
-      deleteHisto = registry.newTimeHistogram(userDeleteKey);
-      incrementHisto = registry.newTimeHistogram(userIncrementKey);
-      appendHisto = registry.newTimeHistogram(userAppendKey);
-      replayHisto = registry.newTimeHistogram(userReplayKey);
-    }
+    getHisto = registry.newTimeHistogram(userGetKey);
+    scanTimeHisto = registry.newTimeHistogram(userScanTimeKey);
+    putHisto = registry.newTimeHistogram(userPutKey);
+    deleteHisto = registry.newTimeHistogram(userDeleteKey);
+    incrementHisto = registry.newTimeHistogram(userIncrementKey);
+    appendHisto = registry.newTimeHistogram(userAppendKey);
+    replayHisto = registry.newTimeHistogram(userReplayKey);
   }
 
   @Override
@@ -159,15 +157,13 @@ public void deregister() {
       LOG.debug("Removing user Metrics for user: " + user);
     }
 
-    synchronized (this) {
-      registry.removeMetric(userGetKey);
-      registry.removeMetric(userScanTimeKey);
-      registry.removeMetric(userPutKey);
-      registry.removeMetric(userDeleteKey);
-      registry.removeMetric(userIncrementKey);
-      registry.removeMetric(userAppendKey);
-      registry.removeMetric(userReplayKey);
-    }
+    registry.removeMetric(userGetKey);
+    registry.removeMetric(userScanTimeKey);
+    registry.removeMetric(userPutKey);
+    registry.removeMetric(userDeleteKey);
+    registry.removeMetric(userIncrementKey);
+    registry.removeMetric(userAppendKey);
+    registry.removeMetric(userReplayKey);
   }
 
   @Override