HADOOP-19061 Capture exception from rpcRequestSender.start() in IPC.Connection.run() (#6519)

* HADOOP-19061 - Capture exception from rpcRequestSender.start() in IPC.Connection.run() and proper cleaning is followed if an exception is thrown.

---------

Co-authored-by: Xing Lin <xinglin@linkedin.com>

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java

@@ -1081,15 +1081,15 @@ private synchronized void sendPing() throws IOException {
 
     @Override
     public void run() {
-      // Don't start the ipc parameter sending thread until we start this
-      // thread, because the shutdown logic only gets triggered if this
-      // thread is started.
-      rpcRequestThread.start();
-      if (LOG.isDebugEnabled())
-        LOG.debug(getName() + ": starting, having connections " 
-            + connections.size());
-
       try {
+        // Don't start the ipc parameter sending thread until we start this
+        // thread, because the shutdown logic only gets triggered if this
+        // thread is started.
+        rpcRequestThread.start();
+        if (LOG.isDebugEnabled()) {
+          LOG.debug(getName() + ": starting, having connections " + connections.size());
+        }
+
         while (waitForWork()) {//wait here for work - read or close connection
           receiveRpcResponse();
         }
@@ -1097,15 +1097,17 @@ public void run() {
         // This truly is unexpected, since we catch IOException in receiveResponse
         // -- this is only to be really sure that we don't leave a client hanging
         // forever.
-        LOG.warn("Unexpected error reading responses on connection " + this, t);
+        String msg = String.format("Unexpected error on connection %s. Closing it.", this);
-        markClosed(new IOException("Error reading responses", t));
+        LOG.warn(msg, t);
+        markClosed(new IOException(msg, t));
       }
 
       close();
 
-      if (LOG.isDebugEnabled())
+      if (LOG.isDebugEnabled()) {
         LOG.debug(getName() + ": stopped, remaining connections "
             + connections.size());
+      }
     }
 
     /**