HDFS-3342. SocketTimeoutException in BlockSender.sendChunks could have a better error message. Contributed by Yongjun Zhang.

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

@@ -319,6 +319,9 @@ Release 2.7.0 - UNRELEASED
 
     HDFS-7280. Use netty 4 in WebImageViewer. (wheat9)
 
+    HDFS-3342. SocketTimeoutException in BlockSender.sendChunks could
+    have a better error message. (Yongjun Zhang via wang)
+
   OPTIMIZATIONS
 
   BUG FIXES

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

@@ -574,12 +574,9 @@ class BlockSender implements java.io.Closeable {
          * writing to client timed out.  This happens if the client reads
          * part of a block and then decides not to read the rest (but leaves
          * the socket open).
+         * 
+         * Reporting of this case is done in DataXceiver#run
          */
-        if (LOG.isTraceEnabled()) {
-          LOG.trace("Failed to send data:", e);
-        } else {
-          LOG.info("Failed to send data: " + e);
-        }
       } else {
         /* Exception while writing to the client. Connection closure from
          * the other end is mostly the case and we do not care much about

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

@@ -39,6 +39,7 @@ import java.io.OutputStream;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 import java.net.SocketException;
+import java.net.SocketTimeoutException;
 import java.nio.channels.ClosedChannelException;
 import java.security.MessageDigest;
 import java.util.Arrays;
@@ -240,6 +241,15 @@ class DataXceiver extends Receiver implements Runnable {
         } else {
           LOG.info(s + "; " + t);
         }
+      } else if (op == Op.READ_BLOCK && t instanceof SocketTimeoutException) {
+        String s1 =
+            "Likely the client has stopped reading, disconnecting it";
+        s1 += " (" + s + ")";
+        if (LOG.isTraceEnabled()) {
+          LOG.trace(s1, t);
+        } else {
+          LOG.info(s1 + "; " + t);          
+        }
       } else {
         LOG.error(s, t);
       }
@@ -520,9 +530,11 @@ class DataXceiver extends Receiver implements Runnable {
       /* What exactly should we do here?
        * Earlier version shutdown() datanode if there is disk error.
        */
-      LOG.warn(dnR + ":Got exception while serving " + block + " to "
+      if (!(ioe instanceof SocketTimeoutException)) {
+        LOG.warn(dnR + ":Got exception while serving " + block + " to "
           + remoteAddress, ioe);
-      datanode.metrics.incrDatanodeNetworkErrors();
+        datanode.metrics.incrDatanodeNetworkErrors();
+      }
       throw ioe;
     } finally {
       IOUtils.closeStream(blockSender);