diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java
index c977f6294b2ad..130c6934a5976 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BPServiceActor.java
@@ -33,9 +33,13 @@
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.atomic.AtomicBoolean;
 
+import com.google.common.collect.Maps;
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.ha.HAServiceProtocol.HAServiceState;
 import org.apache.hadoop.hdfs.client.BlockReportOptions;
@@ -92,6 +96,8 @@ class BPServiceActor implements Runnable {
 
   volatile long lastCacheReport = 0;
   private final Scheduler scheduler;
+  private final Object sendIBRLock;
+  private final ExecutorService ibrExecutorService;
 
   Thread bpThread;
   DatanodeProtocolClientSideTranslatorPB bpNamenode;
@@ -101,6 +107,7 @@ static enum RunningState {
   }
 
   private volatile RunningState runningState = RunningState.CONNECTING;
+  private volatile boolean sendImmediateIBR = false;
   private volatile boolean shouldServiceRun = true;
   private final DataNode dn;
   private final DNConf dnConf;
@@ -135,6 +142,10 @@ static enum RunningState {
         dnConf.getLifelineIntervalMs(), dnConf.blockReportInterval,
         dnConf.outliersReportIntervalMs);
     // get the value of maxDataLength.
+    sendIBRLock = new Object();
+    ibrExecutorService = Executors.newSingleThreadExecutor(
+            new ThreadFactoryBuilder().setDaemon(true)
+                    .setNameFormat("ibr-executor-%d").build());
     this.maxDataLength = dnConf.getMaxDataLength();
   }
 
@@ -349,6 +360,11 @@ private long generateUniqueBlockReportId() {
    * @throws IOException
    */
   List<DatanodeCommand> blockReport(long fullBrLeaseId) throws IOException {
+
+    synchronized (sendIBRLock) {
+      reportReceivedDeletedBlocks();
+    }
+
     final ArrayList<DatanodeCommand> cmds = new ArrayList<DatanodeCommand>();
 
     // Flush any block information that precedes the block report. Otherwise
@@ -569,6 +585,9 @@ void stop() {
     if (bpThread != null) {
       bpThread.interrupt();
     }
+    if (ibrExecutorService != null && !ibrExecutorService.isShutdown()) {
+      ibrExecutorService.shutdownNow();
+    }
   }
 
   //This must be called only by blockPoolManager
@@ -590,6 +609,9 @@ private synchronized void cleanUp() {
     IOUtils.cleanup(null, bpNamenode);
     IOUtils.cleanup(null, lifelineSender);
     bpos.shutdownActor(this);
+    if (!ibrExecutorService.isShutdown()) {
+      ibrExecutorService.shutdownNow();
+    }
   }
 
   private void handleRollingUpgradeStatus(HeartbeatResponse resp) throws IOException {
@@ -842,6 +864,8 @@ public void run() {
       }
 
       runningState = RunningState.RUNNING;
+      ibrExecutorService.submit(new IBRTaskHandler());
+
       if (initialRegistrationComplete != null) {
         initialRegistrationComplete.countDown();
       }
@@ -1275,4 +1299,5 @@ public long monotonicNow() {
       return Time.monotonicNow();
     }
   }
+
 }
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
index 81b0d67c38238..32789ed4d4c00 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/impl/FsDatasetImpl.java
@@ -243,13 +243,18 @@ ReplicaInfo fetchReplicaInfo(String bpid, long blockId) {
   @Override // FsDatasetSpi
   public LengthInputStream getMetaDataInputStream(ExtendedBlock b)
       throws IOException {
-    File meta = FsDatasetUtil.getMetaFile(getBlockFile(b), b.getGenerationStamp());
-    FsVolumeSpi volume = null;
+    File meta = null;
+    try {
+      meta = FsDatasetUtil.getMetaFile(getBlockFile(b), b.getGenerationStamp());
+    } catch (IOException e) {
+      throw new FileNotFoundException("BlockId " + b.getBlockName() + " is not valid.");
+    }
 
     if (meta == null || !meta.exists()) {
       return null;
     }
 
+    FsVolumeSpi volume = null;
     try (AutoCloseableLock lock = datasetWriteLock.acquire()) {
       final ReplicaInfo replicaInfo = getReplicaInfo(b);
       if (replicaInfo != null) {
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBlockReports.java b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBlockReports.java
index 03553fed4f3a7..e2fc94dcd6468 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBlockReports.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestIncrementalBlockReports.java
@@ -42,6 +42,7 @@
 import org.junit.Before;
 import org.junit.Test;
 import org.mockito.Mockito;
+import org.mockito.exceptions.base.MockitoAssertionError;
 
 /**
  * Verify that incremental block reports are generated in response to
@@ -124,7 +125,7 @@ public void testReportBlockReceived() throws InterruptedException, IOException {
 
       // Sleep for a very short time, this is necessary since the IBR is
       // generated asynchronously.
-      Thread.sleep(2000);
+      Thread.sleep(1000);
 
       // Ensure that the received block was reported immediately.
       Mockito.verify(nnSpy, times(1)).blockReceivedAndDeleted(
@@ -166,13 +167,28 @@ public void testReportBlockDeleted() throws InterruptedException, IOException {
 
       // Trigger a heartbeat, this also triggers an IBR.
       DataNodeTestUtils.triggerHeartbeat(singletonDn);
-      Thread.sleep(2000);
 
       // Ensure that the deleted block is reported.
       Mockito.verify(nnSpy, times(1)).blockReceivedAndDeleted(
           any(DatanodeRegistration.class),
           anyString(),
           any(StorageReceivedDeletedBlocks[].class));
+      int retries = 0;
+      while (true) {
+        try {
+          Mockito.verify(nnSpy, atLeastOnce()).blockReceivedAndDeleted(
+                  any(DatanodeRegistration.class),
+                  anyString(),
+                  any(StorageReceivedDeletedBlocks[].class));
+          break;
+        } catch (MockitoAssertionError e) {
+          if (retries > 7) {
+            throw e;
+          }
+          retries++;
+          Thread.sleep(2000);
+        }
+      }
 
     } finally {
       cluster.shutdown();