svn merge -c 1296016 FIXES: HDFS-3037. TestMulitipleNNDataBlockScanner#testBlockScannerAfterRestart is racy. Contributed by Aaron T. Myers.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1359242 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -1177,6 +1177,9 @@ Release 0.23.3 - UNRELEASED
     HDFS-3331. In namenode, check superuser privilege for setBalancerBandwidth
     and acquire the write lock for finalizeUpgrade.  (szetszwo)
 
+    HDFS-3037. TestMulitipleNNDataBlockScanner#testBlockScannerAfterRestart is
+    racy. (atm)
+
 Release 0.23.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestMulitipleNNDataBlockScanner.java

@@ -149,6 +149,9 @@ public class TestMulitipleNNDataBlockScanner {
       cluster.waitActive();
       DataNode dn = cluster.getDataNodes().get(0);
       for (int i = 0; i < 3; i++) {
+        while (!dn.blockScanner.isInitialized(bpids[i])) {
+          Thread.sleep(1000);
+        }
         long blocksScanned = 0;
         while (blocksScanned != 20) {
           if (dn.blockScanner != null) {