Bug: client fails forever when namenode ipaddr changed
Status: Resolved | Priority: Major | Resolution: Fixed
Created: 05/Jun/20 09:17

For machine replacement, I replace my standby namenode with a new ipaddr and keep the same hostname. Also update the client's hosts to make it resolve correctly

When I try to run failover to transite the new namenode(let's say nn2), the client will fail to read or write forever until it's restarted.

That make yarn nodemanager in sick state. Even the new tasks will encounter this exception  too. Until all nodemanager restart.

 
{code:java}
20/06/02 15:12:25 WARN ipc.Client: Address change detected. Old: nn2-192-168-1-100/192.168.1.100:9000 New: nn2-192-168-1-100/192.168.1.200:9000
20/06/02 15:12:25 DEBUG ipc.Client: closing ipc connection to nn2-192-168-1-100/192.168.1.200:9000: Connection refused
java.net.ConnectException: Connection refused
        at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
        at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:717)
        at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:530)
        at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:494)
        at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:608)
        at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:707)
        at org.apache.hadoop.ipc.Client$Connection.access$2800(Client.java:368)
        at org.apache.hadoop.ipc.Client.getConnection(Client.java:1517)
        at org.apache.hadoop.ipc.Client.call(Client.java:1440)
        at org.apache.hadoop.ipc.Client.call(Client.java:1401)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:232)
        at com.sun.proxy.$Proxy9.addBlock(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:399)
        at sun.reflect.GeneratedMethodAccessor8.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:193)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102)
{code}
 

We can see the client has {{Address change detected}}, but it still fails. I find out that's because when method {{updateAddress()}} return true,  the {{handleConnectionFailure()}} thow an exception that break the next retry with the right ipaddr.

Client.java: setupConnection()
{code:java}
        } catch (ConnectTimeoutException toe) {
          /* Check for an address change and update the local reference.
           * Reset the failure counter if the address was changed
           */
          if (updateAddress()) {
            timeoutFailures = ioFailures = 0;
          }
          handleConnectionTimeout(timeoutFailures++,
              maxRetriesOnSocketTimeouts, toe);
        } catch (IOException ie) {
          if (updateAddress()) {
            timeoutFailures = ioFailures = 0;
          }
// because the namenode ip changed in updateAddress(), the old namenode ipaddress cannot be accessed now
// handleConnectionFailure will thow an exception, the next retry never have a chance to use the right server updated in updateAddress()
          handleConnectionFailure(ioFailures++, ie);
        }
{code}