HDFS-14021. TestReconstructStripedBlocksWithRackAwareness#testReconstructForNotEnoughRacks fails intermittently. Contributed by Xiao Chen.

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestReconstructStripedBlocksWithRackAwareness.java

@@ -162,7 +162,9 @@ public class TestReconstructStripedBlocksWithRackAwareness {
     // the file's block is in 9 dn but 5 racks
     DFSTestUtil.createFile(fs, file,
         cellSize * dataBlocks * 2, (short) 1, 0L);
-    Assert.assertEquals(0, bm.numOfUnderReplicatedBlocks());
+    GenericTestUtils.waitFor(() ->
+        bm.numOfUnderReplicatedBlocks() == 0, 100, 30000);
+    LOG.info("Created file {}", file);
 
     final INodeFile fileNode = fsn.getFSDirectory()
         .getINode4Write(file.toString()).asFile();
@@ -173,7 +175,8 @@ public class TestReconstructStripedBlocksWithRackAwareness {
     for (DatanodeStorageInfo storage : blockInfo.storages) {
       rackSet.add(storage.getDatanodeDescriptor().getNetworkLocation());
     }
-    Assert.assertEquals(dataBlocks - 1, rackSet.size());
+    Assert.assertEquals("rackSet size is wrong: " + rackSet, dataBlocks - 1,
+        rackSet.size());
 
     // restart the stopped datanode
     cluster.restartDataNode(lastHost);
@@ -181,6 +184,7 @@ public class TestReconstructStripedBlocksWithRackAwareness {
 
     // make sure we have 6 racks again
     NetworkTopology topology = bm.getDatanodeManager().getNetworkTopology();
+    LOG.info("topology is: {}", topology);
     Assert.assertEquals(hosts.length, topology.getNumOfLeaves());
     Assert.assertEquals(dataBlocks, topology.getNumOfRacks());
 
@@ -202,7 +206,8 @@ public class TestReconstructStripedBlocksWithRackAwareness {
       for (DatanodeStorageInfo storage : blockInfo.storages) {
         if (storage != null) {
           DatanodeDescriptor dn = storage.getDatanodeDescriptor();
-          Assert.assertEquals(0, dn.getNumberOfBlocksToBeErasureCoded());
+          Assert.assertEquals("Block to be erasure coded is wrong for datanode:"
+              + dn, 0, dn.getNumberOfBlocksToBeErasureCoded());
           if (dn.getNumberOfBlocksToBeReplicated() == 1) {
             scheduled = true;
           }