HDFS-7213. processIncrementalBlockReport performance degradation.

Contributed by Eric Payne.
(cherry picked from commit e226b5b40d)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -59,6 +59,9 @@ Release 2.7.0 - UNRELEASED
     HDFS-5928. Show namespace and namenode ID on NN dfshealth page.
     (Siqi Li via wheat9)
 
+    HDFS-7213. processIncrementalBlockReport performance degradation.
+    (Eric Payne via kihwal)
+
   OPTIMIZATIONS
 
   BUG FIXES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/BlockManager.java

@@ -3078,9 +3078,11 @@ public class BlockManager {
             + " is received from " + nodeID);
       }
     }
-    blockLog.debug("*BLOCK* NameNode.processIncrementalBlockReport: " + "from "
+    if (blockLog.isDebugEnabled()) {
+      blockLog.debug("*BLOCK* NameNode.processIncrementalBlockReport: " + "from "
         + nodeID + " receiving: " + receiving + ", " + " received: " + received
         + ", " + " deleted: " + deleted);
+    }
   }
 
   /**