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From "Jagane Sundar (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HDFS-4858) HDFS DataNode to NameNode RPC should timeout
Date Thu, 08 Aug 2013 00:45:48 GMT

    [ https://issues.apache.org/jira/browse/HDFS-4858?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13733002#comment-13733002
] 

Jagane Sundar commented on HDFS-4858:
-------------------------------------

I am concerned that we might not even be able to write a Unit Test for this bug.

The essential sequence of events for this bug is this:

1. Datanode should be connected to both Active and Standby NNs
2. Standby NN should die without sending the TCP RST to the DataNode. If the RST is sent out,
then the DataNode thread waiting on this Socket will get a SocketException, and all is fine.
It will keep trying to re-connect to the SNN, and will succeed when the SNN comes back to
life. This is fine. The problem really happens only when the network interface dies abruptly.
In this case, the TCP RST does not go out, so the DN side of the TCP connection never knows
that the SNN rebooted. This is not such an unusual occurrence - an unexpected power loss for
the SNN would cause exactly this situation

Note the following:
1. Kill -9 of the SNN will cause a TCP RST to be sent out
2. Reboot of the SNN machine will also cause a TCP RST to be sent out

How can we mock such a death of the SNN?

                
> HDFS DataNode to NameNode RPC should timeout
> --------------------------------------------
>
>                 Key: HDFS-4858
>                 URL: https://issues.apache.org/jira/browse/HDFS-4858
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode
>    Affects Versions: 3.0.0, 2.1.0-beta, 2.0.4-alpha, 2.0.5-alpha
>         Environment: Redhat/CentOS 6.4 64 bit Linux
>            Reporter: Jagane Sundar
>            Priority: Minor
>         Attachments: HDFS-4858.patch
>
>
> The DataNode is configured with ipc.client.ping false and ipc.ping.interval 14000. This
configuration means that the IPC Client (DataNode, in this case) should timeout in 14000 seconds
if the Standby NameNode does not respond to a sendHeartbeat.
> What we observe is this: If the Standby NameNode happens to reboot for any reason, the
DataNodes that are heartbeating to this Standby get stuck forever while trying to sendHeartbeat.
See Stack trace included below. When the Standby NameNode comes back up, we find that the
DataNode never re-registers with the Standby NameNode. Thereafter failover completely fails.
> The desired behavior is that the DataNode's sendHeartbeat should timeout in 14 seconds,
and keep retrying till the Standby NameNode comes back up. When it does, the DataNode should
reconnect, re-register, and offer service.
> Specifically, in the class DatanodeProtocolClientSideTranslatorPB.java, the method createNamenode
should use RPC.getProtocolProxy and not RPC.getProxy to create the DatanodeProtocolPB object.
> Stack trace of thread stuck in the DataNode after the Standby NN has rebooted:
> Thread 25 (DataNode: [file:///opt/hadoop/data]  heartbeating to vmhost6-vm1/10.10.10.151:8020):
>   State: WAITING
>   Blocked count: 23843
>   Waited count: 45676
>   Waiting on org.apache.hadoop.ipc.Client$Call@305ab6c5
>   Stack:
>     java.lang.Object.wait(Native Method)
>     java.lang.Object.wait(Object.java:485)
>     org.apache.hadoop.ipc.Client.call(Client.java:1220)
>     org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:202)
>     sun.proxy.$Proxy10.sendHeartbeat(Unknown Source)
>     sun.reflect.GeneratedMethodAccessor2.invoke(Unknown Source)
>     sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
>     java.lang.reflect.Method.invoke(Method.java:597)
>     org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:164)
>     org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:83)
>     sun.proxy.$Proxy10.sendHeartbeat(Unknown Source)
>     org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB.sendHeartbeat(DatanodeProtocolClientSideTranslatorPB.java:167)
>     org.apache.hadoop.hdfs.server.datanode.BPServiceActor.sendHeartBeat(BPServiceActor.java:445)
>     org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:525)
>     org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:676)
>     java.lang.Thread.run(Thread.java:662)
> DataNode RPC to Standby NameNode never times out. 

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