diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
index a900ad191da..9452b8b1b2b 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/balancer/TestBalancer.java
@@ -2084,7 +2084,7 @@ public class TestBalancer {
     initConf(conf);
     conf.setInt(DFSConfigKeys.DFS_BALANCER_DISPATCHERTHREADS_KEY, 30);
 
-    int numDNs = 40;
+    int numDNs = 20;
     long[] capacities = new long[numDNs];
     String[] racks = new String[numDNs];
     for(int i = 0; i < numDNs; i++) {