HDFS-15077. Fix intermittent failure of TestDFSClientRetries#testLeaseRenewSocketTimeout. (#1797)

hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/client/impl/LeaseRenewer.java

@@ -270,8 +270,9 @@ public class LeaseRenewer {
         half: LEASE_RENEWER_SLEEP_DEFAULT;
   }
 
+  @VisibleForTesting
   /** Is the daemon running? */
-  synchronized boolean isRunning() {
+  public synchronized boolean isRunning() {
     return daemon != null && daemon.isAlive();
   }
 

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/TestDFSClientRetries.java

@@ -387,13 +387,14 @@ public class TestDFSClientRetries {
           Mockito.anyString());
       DFSClient client = new DFSClient(null, spyNN, conf, null);
       // Get hold of the lease renewer instance used by the client
-      LeaseRenewer leaseRenewer = client.getLeaseRenewer();
-      leaseRenewer.setRenewalTime(100);
+      final LeaseRenewer leaseRenewer1 = client.getLeaseRenewer();
+      leaseRenewer1.setRenewalTime(100);
       OutputStream out1 = client.create(file1, false);
 
       Mockito.verify(spyNN, timeout(10000).times(1)).renewLease(
           Mockito.anyString());
-      verifyEmptyLease(leaseRenewer);
+      verifyEmptyLease(leaseRenewer1);
+      GenericTestUtils.waitFor(() -> !(leaseRenewer1.isRunning()), 100, 10000);
       try {
         out1.write(new byte[256]);
         fail("existing output stream should be aborted");
@@ -406,14 +407,14 @@ public class TestDFSClientRetries {
       // throws SocketTimeoutException.
       Mockito.doNothing().when(spyNN).renewLease(
           Mockito.anyString());
-      leaseRenewer = client.getLeaseRenewer();
-      leaseRenewer.setRenewalTime(100);
+      final LeaseRenewer leaseRenewer2 = client.getLeaseRenewer();
+      leaseRenewer2.setRenewalTime(100);
       OutputStream out2 = client.create(file2, false);
       Mockito.verify(spyNN, timeout(10000).times(2)).renewLease(
           Mockito.anyString());
       out2.write(new byte[256]);
       out2.close();
-      verifyEmptyLease(leaseRenewer);
+      verifyEmptyLease(leaseRenewer2);
     } finally {
       cluster.shutdown();
     }
@@ -758,11 +759,7 @@ public class TestDFSClientRetries {
   }
 
   private void verifyEmptyLease(LeaseRenewer leaseRenewer) throws Exception {
-    int sleepCount = 0;
-    while (!leaseRenewer.isEmpty() && sleepCount++ < 20) {
-      Thread.sleep(500);
-    }
-    assertTrue("Lease should be empty.", leaseRenewer.isEmpty());
+    GenericTestUtils.waitFor(() -> leaseRenewer.isEmpty(), 100, 10000);
   }
 
   class DFSClientReader implements Runnable {