HDFS-8894. Set SO_KEEPALIVE on DN server sockets. Contributed by Kanaka Kumar Avvaru.

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

@@ -131,6 +131,7 @@ class DataStreamer extends Daemon {
     NetUtils.connect(sock, isa, client.getRandomLocalInterfaceAddr(),
         conf.getSocketTimeout());
     sock.setSoTimeout(timeout);
+    sock.setKeepAlive(true);
     if (conf.getSocketSendBufferSize() > 0) {
       sock.setSendBufferSize(conf.getSocketSendBufferSize());
     }

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

@@ -1761,6 +1761,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-9535. Newly completed blocks in IBR should not be considered
     under-replicated too quickly. (Mingliang Liu via jing9)
 
+    HDFS-8894. Set SO_KEEPALIVE on DN server sockets.
+    (Kanaka Kumar Avvaru via wang)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

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

@@ -710,6 +710,7 @@ class DataXceiver extends Receiver implements Runnable {
               (HdfsConstants.WRITE_TIMEOUT_EXTENSION * targets.length);
           NetUtils.connect(mirrorSock, mirrorTarget, timeoutValue);
           mirrorSock.setSoTimeout(timeoutValue);
+          mirrorSock.setKeepAlive(true);
           if (dnConf.getTransferSocketSendBufferSize() > 0) {
             mirrorSock.setSendBufferSize(
                 dnConf.getTransferSocketSendBufferSize());
@@ -1127,7 +1128,8 @@ class DataXceiver extends Receiver implements Runnable {
         proxySock = datanode.newSocket();
         NetUtils.connect(proxySock, proxyAddr, dnConf.socketTimeout);
         proxySock.setSoTimeout(dnConf.socketTimeout);
-        
+        proxySock.setKeepAlive(true);
+
         OutputStream unbufProxyOut = NetUtils.getOutputStream(proxySock,
             dnConf.socketWriteTimeout);
         InputStream unbufProxyIn = NetUtils.getInputStream(proxySock);