HDFS-8729. Fix TestFileTruncate#testTruncateWithDataNodesRestartImmediately which occasionally failed. Contributed by Walter Su.

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

@@ -1023,6 +1023,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-8642. Make TestFileTruncate more reliable. (Rakesh R via
     Arpit Agarwal)
 
+    HDFS-8729. Fix TestFileTruncate#testTruncateWithDataNodesRestartImmediately
+    which occasionally failed. (Walter Su via jing9)
+
 Release 2.7.2 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/namenode/TestFileTruncate.java

@@ -804,6 +804,9 @@ public class TestFileTruncate {
     assertEquals(newBlock.getBlock().getGenerationStamp(),
         oldBlock.getBlock().getGenerationStamp() + 1);
 
+    Thread.sleep(2000);
+    // trigger the second time BR to delete the corrupted replica if there's one
+    cluster.triggerBlockReports();
     // Wait replicas come to 3
     DFSTestUtil.waitReplication(fs, p, REPLICATION);
     // Old replica is disregarded and replaced with the truncated one on dn0