[GitHub] dawidwys commented on a change in pull request #6862: [FLINK-10213] Task managers cache a negative DNS lookup of the blob server indefinitely

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dawidwys commented on a change in pull request #6862: [FLINK-10213] Task managers cache a negative DNS lookup of the blob server indefinitely
URL: https://github.com/apache/flink/pull/6862#discussion_r237878535
 
 

 ##########
 File path: flink-runtime/src/main/java/org/apache/flink/runtime/blob/BlobClient.java
 ##########
 @@ -87,12 +87,13 @@ public BlobClient(InetSocketAddress serverAddress, Configuration clientConfig) t
 				LOG.info("Using ssl connection to the blob server");
 
 				socket = SSLUtils.createSSLClientSocketFactory(clientConfig).createSocket(
-					serverAddress.getAddress(),
+					serverAddress.getHostName(),
 					serverAddress.getPort());
 			}
 			else {
-				socket = new Socket();
-				socket.connect(serverAddress);
+				// Establish the socket using the hostname and port. This avoids a potential issue where the
+				// InetSocketAddress can cache a failure in hostname resolution forever.
+				socket = new Socket(serverAddress.getHostName(), serverAddress.getPort());
 
 Review comment:
   How about doing the lookup only if the `InetSocketAddress` was not resolved?
   
   ```
   socket = new Socket();
   if (serverAddress.isUnresolved()) {
   	socket.connect(new InetSocketAddress(serverAddress.getHostName(), serverAddress.getPort()));
   } else {
   	socket.connect(serverAddress);
   }
   ```

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