HDFS-10773. BlockSender should not synchronize on the dataset object. (Contributed by Chen Liang)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/BlockSender.java

@@ -46,6 +46,7 @@ import org.apache.hadoop.io.LongWritable;
 import org.apache.hadoop.io.ReadaheadPool.ReadaheadRequest;
 import org.apache.hadoop.io.nativeio.NativeIO;
 import org.apache.hadoop.net.SocketOutputStream;
+import org.apache.hadoop.util.AutoCloseableLock;
 import org.apache.hadoop.util.DataChecksum;
 import org.apache.htrace.core.TraceScope;
 
@@ -239,7 +240,7 @@ class BlockSender implements java.io.Closeable {
       
       final Replica replica;
       final long replicaVisibleLength;
-      synchronized(datanode.data) { 
+      try(AutoCloseableLock lock = datanode.data.acquireDatasetLock()) {
         replica = getReplica(block, datanode);
         replicaVisibleLength = replica.getVisibleLength();
       }